Unit 19 (Biology Part 2)

All About Kidneys

Thursday August 15, 2013

Although urine is sterile, it has hundreds of different kinds of wastes from the body. All sorts of things affect what is in your urine, including last night’s dinner, how much water you drink, what you do for exercise, and how well your kidneys work in the first place. This experiment will show you how the kidneys work to keep your body in top shape.

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Materials

1 liter of water per student
1 can of soda per student
1 sports drink, like Gatorade, per student
Red food dye
Chalk (or a handful of sand)
Coffee filter or cheesecloth
pH paper strips
Disposable cups
Clean glass jar
Rubber band
Measuring cups

If you are doing the optional Third Bonus Experiment:

solution your teacher has prepared for you
pipe cleaners
cleaned out jar or bottle (pickle, jam, or mayo jar)
water
borax

Download Student Worksheet & Exercises

Experiment

First Experiment: How Quickly Do the Kidneys Process Fluids?

Drink a liter of water quickly (in less than five minutes).
Wait 20 minutes (you can start on the second part of this lab while you wait) and then collect your urine in a disposable cup in the bathroom and use a pH testing strip to test the pH by dipping it in the cup.
Repeat four times so that you have four samples collected 20 minutes apart.
Repeat steps 1-3 for two different liquids, such as a sports drink and a soda.
Complete the data table for all three liquids.

Second Experiment: Kidney Filtration

Crush a piece of chalk and place it in a clean glass jar. (You can alternatively use a handful of sand from the playground if you don’t have chalk.)
Fill the jar partway with water.
Add a few drops of red food coloring to the water.
The chalk (or sand) represents toxins in the blood. The water represents the blood.
Place a coffee filter (or cheesecloth) on top of the jar and secure with a rubber band. This coffee filter is your kidney.
Tip the jar over a disposable cup and pour the contents into the disposable cup. This is the kidney filtering the blood.
Observe what the filter traps and what it doesn’t and record your observations in the data table.

BONUS Third Experiment: Kidney Stones

A kidney stone is something that develops in the urinary tract from a crystal. Crystals start from “seed crystals” that grow when placed in the right solution.
Use a pipe cleaner to create a shape for crystals to cling to (suggestion: cut into 3 lengths and wrap around one another). Curl the top pipe cleaner around a pencil, making sure the shape will hang nicely in the container without touching the sides.
Add 2 cups of water and 2 cups of borax (sodium tetraborate) into a pot. Heat, stirring continuously for about 5-10 minutes. Do not boil, but only heat until steam rises from the pan.
When the borax has dissolved, add more, and continue to do so until there are bits of borax settling on the bottom of the pan that cannot be stirred in (It may be necessary to stop heating and let the solution settle if it gets too cloudy). You’ll be adding in a lot of borax! You have now made a supersaturated solution. Make sure your solution is saturated, or your crystals will not grow.
Wait until your solution has cooled to about 130^oF (hot to the touch, but not so hot that you yank your hand away). Pour this solution (just the liquid, not the solid bits) into the jar, and add the pipe cleaner shape. Make sure the pipe cleaner is submerged in the solution. Put the jar in a place where the crystals can grow undisturbed overnight, or even for a few days. Warmer locations (such as upstairs or on top shelves) are best.
NOTE: These crystals are NOT edible! Please keep them away from small children and pets!

Kidneys Process Fluids Data Table

Record the pH and volume (did you urinate a lot, medium, or little?)

Drink Type	20 min	40 min	60 min	80 min

Urine tests look at different components of urine. Most urine tests are done to get information about the body’s health and clarify problems that it might be having. There are over 100 different kinds of urine tests that can be done. Depending on the test, scientists look for different things.

The most obvious, and the one you can do yourself at home, is to look at the color of urine, which is normally clear. Many different things affect urine color, and the darker it is, the less water there is in it. Vitamin B supplements can turn it bright yellow. If you like to eat blackberries, beets or rhubarb, then your urine might be red-brown.

The next thing to check is smell. Since urine doesn’t smell much, it’s a signal if it suddenly takes on an unusual odor. For example, if you have an E. coli infection, your urine will take on a bad odor.

Scientists also check the specific gravity, which is a measure of the amount of substances in the urine. The higher the specific gravity number measures, the more substance is in the urine. For example, when you drink a lot of water, your kidneys add that water into the urine, which makes for a lower the specific gravity number. This test shows how well the kidneys balance the amount of water in urine. The specific gravity for normal urine is between 1.005-1.030.

pH is a measure of how basic or acidic something is, and for a urine test, it’s the pH of the urine itself. A pH of 7 is neutral, a 9 is strongly basic, and a 4 is strongly acidic. Using a strip of pH paper will tell you how basic or acidic your urine is. Normally, pH is between 4.6-8.0 for urine.

Protein is not supposed to be in the urine, unless you’re sick with a fever, just had a hard workout session, or are pregnant. Scientists look for protein to be present in the urine to detect certain kinds of kidney diseases.

Glucose is sugar in the blood, and usually there’s no glucose in urine, or if there is, it’s only a tiny bit. When scientists detect glucose in the urine, it means that the body’s blood sugar levels are very high, and they know they need to look into things further.

When scientists find nitrites, they know that bacteria are present, especially the kind that cause a urinary tract infection because bacteria make an enzyme that changes nitrates to nitrites in the urine.

Strong, healthy people will have a couple of small crystals in their urine. If scientists find a large number of crystals, then they start looking for kidney stones. If they don’t find kidney stones, then they start looking at how the body metabolizes food to see if there’s a problem.

Most adults make about 1-2 quarts of urine each day, and kids make about 0.6-1.6 quarts per day

Kidneys Filtration Data Table

Amount of Chalk or Sand	Amount of Water	Color of Water after Mixed	Amount of Solids Filtered Out by Cheesecloth

Questions:

Which fluid produced more urine for the first experiment?
Did the caffeine solutions cause the calcite stones to shrink or have no effect?
What does pouring the chalky water through a coffee filter show?
What are kidney stones and how are they formed?

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PTC Testing

Friday November 18, 2011

We have done some extensive experiments on taste buds: how they are categorized, what tastes they recognize, and we have even mapped their location on your tongue. But we haven’t yet mentioned this fact: not all people can taste the same flavors!

So today we will check to see if you have a dominant or recessive gene for a distinct genetic characteristic. We’ll do this by testing your reaction to the taste of a chemical called phenylthiocarbamide (or PTC, for short). The interesting thing about PTC is that some people can taste it – and generally have a very adverse reaction. However, some people can’t taste it at all.

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Here’s what you need

1 vial of PTC paper
family members

Download Student Worksheet & Exercises

Here’s what you do

Put the PTC paper in your mouth. If you have the dominant gene, it will usually taste pretty bitter. It might also be sour or even a little sweet. If it tastes like a piece of paper, you have a recessive gene.
After testing your paper, be sure to note whether you are a taster or non-taster.
Now test at least five more people in your family and note their reactions as tasters or non-tasters. Also note their relationship to you.
If you have enough PTC paper, make a genetic tree of your responses. Put Mom and Dad at the center and list you and your siblings branching out beneath them. Then list both sets of grandparents above each of your parents. Circle the names of family members who test positive and leave the negative testers uncircled.

What’s going on?

The gene that determines whether or not you can taste PTC is a part of your DNA (deoxyribonucleic acid). It is the genetic blueprint that you were born with and it determines everything about you: from hair color to the size of your feet. But DNA also plays an important role in how your five senses function. Colorblindness is a genetic deficiency in which a person cannot see colors has a difficult time with distinguishing them. It can range in severity. Some people who are colorblind can’t tell the difference between colors like red and green, but some see no colors at all. Everything looks like a black and white movie to them. Just like colorblindness, our taste sensitivity can vary. Maybe this explains why some people like liver and brussel sprouts and others can’t stand them!

So to relate this to our test, the ability to taste PTC comes from a gene. We know that if both of your parents can taste it, there is a high likelihood that you will be able to taste it, too. About 70%, or 7 out of 10, people can taste it. But what does it mean? In truth, not a lot. It doesn’t mean you have a highly developed palate or a better sense of taste. It just means you are lucky enough to have inherited a gene that allows you to taste a disgusting, bitter chemical on a piece of paper. Congratulations!

Exercises

What are the tiny hair-like organelles that send taste messages to your brain called?
What are the bumps on your tongue called?
What kind of trait does this experiment test?

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Stethoscope

Friday November 18, 2011

Stethoscopes are instruments used to amplify sounds like your heartbeat. Your doctor is trained to use a stethoscope not only to count the beats, but he or she can also hear things like your blood entering and exiting the heart
and its valves opening and closing. Pretty cool!

Today you will make and test a homemade stethoscope. Even though it will be pretty simple, you should still be able to hear your heart beating and your heart pumping. You can also use it to listen to your lungs, just like your doctor does.

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Here’s what you need

3 12-inch lengths of rubber hose
1 “T” connector
1 funnel

Download Student Worksheet & Exercises

Here’s what you do

Take two pieces of hose and work them onto the top ends of the “T” connector. Put the remaining piece of hose onto the bottom of the “T.” The tool you have made should look like a simple stethoscope, but there are no super cold metal end pieces to worry about with yours.
Put the funnel into the bottom hose – the one hanging from the bottom of the “T” connector. You know have a functioning stethoscope. One word of warning: NEVER YELL INTO THE FUNNEL WHILE THE STETHOSCOPE IS ATTACHED TO SOMEONE’S EARS. THIS COULD DAMAGE EAR DRUMS!
Gently insert the side tubes into your ears. Put the funnel on your chest, just to the left of your breastbone. Listen for your heartbeat. If you are in a sufficiently quiet room you may even be able to hear the opening and closing of your heart’s valves.
After you’ve found your hear, try moving the stethoscope to various areas of your chest and listen for different sounds made by your heart. Ask if you can listen to a friend or family member’s heart. Are the sounds made by another heart the same or different?
Now listen to your lungs, placing the end of the stethoscope just above and to the left of the bottom of your ribcage (Point A), to the right of the bottom of your ribcage (Point B), and just below where your ribs start (point C). Also listen in the middle of your back to the left (point D) and right of your spine (point E). In each spot, take a deep breath and listen for the sound of air entering and exiting the lungs.
For your data records, record how many times your heart beats in a minute while you are quiet and sitting.
Next, do 100 jumping jacks. Sit down immediately and check your heart. Record the number of beats per minute for jumping jacks in your data.
Finally, go outside and run for 3 minutes, non-stop. Then sit and immediately check your heart rate one more time. Record the beats per minute for running in your experiment data.

What’s going on?

Exercise creates a demand for oxygen in your muscles, which is received from work done by your heart and lungs. They get a message from your brain and start to work harder. You can see the proof of their hard work in your recorded data.

Exercises

Approximately how big is your heart?
Which body system is the heart a part of?
What are some of this system’s jobs?
How many chambers does your heart have and what are they called?
How did the heart rate change when you exercised?

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What’s Your Lung Capacity?

Friday November 18, 2011

Today you will make a calibrated, or marked, container that you will use to measure your lung capacity. You will fill the calibrated container with water, slide a hose into it, take a really deep breath, and blow in the hose. As the air in your lungs enters the container, it will push out the water inside. Just blow as long and as much as you can, then when you flip the bottle over you will be able to read the amount of water you have displaced. If you will subtract the water displaced from the total amount of water in the bottle, the result is your lung capacity.

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Here’s what you need

- 1 2-liter soda bottle
- 1 black marker, permanent
- 1 12” length of rubber hose
- 1 large plastic bowl
- 1 cup measure

Download Student Worksheet & Exercises

Here’s what you do

Fill the 1 cup measure with water. Pour this into the 2-liter bottle and mark the water level with a line using the black, permanent marker. Also, write 1 cup next to the line. Keep adding water, one cup at a time, marking each new 1 cup increment until you have filled the bottle with water.
Now flip the newly-filled bottle of water over 1 cup measure until the cup is about 1/3 full. Put one end of the rubber hose in the top of the bottle (which should be now under water).
Take a really deep breath – as deep as you can – and blow your breath out into the tube. Continue to blow until you can’t push any more air into the bottle. As air goes in the bottle, it pushes an amount of water equal to its volume out and into the bowl.
Put the lid on the bottle and turn it over before lifting it out of the water. How much water is left in the bottle? Subtract this amount from 8.5 cups. This should be your lung capacity.
Record your lung capacity in your data records as, “My lung capacity is ____________ cups.” You can convert this number to milliliters by multiplying by 0.24. For example, 19 cups would equal 4.5 liters.

What’s going on?

A person who is 70 years old has breathed about 600,000,000 times in their life. But they have also breathed a lot of air – about 13,000,000 cubic feet. This is enough air to fill 52 blimps!

A man’s lungs have a greater capacity than a woman’s – it’s about 6 liters for a man and 4.2 liters for a woman. And since a grown-up has a greater lung capacity than a kid, it makes sense that a 10-year old might breathe 20 times per minute when a grown-up might breathe only 12 times in a minute.

Exercises

Which body system are your lungs a part of?
What are some other parts in this system?
Explain this system’s major function.

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Working Lung Model

Friday November 18, 2011

Food and air both enter your body through your mouth, diverging when they reach the esophagus and trachea. Food goes to the gastrointestinal tract through your esophagus and air travels to your lungs via the trachea, or windpipe.

You will be making a model of how your lungs work in this lab. It will include the trachea, lungs, and the diaphragm, which expands and contracts as it fills and empties your lungs.

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Here’s what you need

1. 1 2-liter soda bottle, emptied and cleaned
2. 1 pair of scissors
3. 1”Y” valve hose connector
4. 3 round, 9-inch balloons
5. 1 #3 one-hole stopper
6. 1 length of hose, 8-inch
7. 2 rubber bands
8. 1 jar of petroleum jelly

Here’s what you do

Cut off the bottom of the 2-liter bottle. Ask an adult for help.
Take the “Y” valve and secure the two balloons to the top branches with the rubber bands.
Put a tiny bit of petroleum jelly on the end of the hose to make it easier to insert into the #3 stopper. Pull 6 inches of hose through the stopper and then thread the hose through the bottle’s neck. Insert the stopper into the top of the bottle.
Put the end of the hose (that is now inside the bottle) into the base of the “Y” valve (which now has balloons on its other branches). Pull the hose through the stopper a bit. Also, pull the lungs up toward the top of the bottle.
Tie a knot in the third, unused balloon. Cut it in half and stretch the part with the knot over the open bottom of the soda bottle. Make sure the bottom balloon is as tight as it can be.
Grab the bottle with one hand, the knot at the bottom of the balloon with the other. Carefully pull the knot on the balloon down. What happens to the balloons in the bottle? Now let go of the knot and observe how this affects the balloons. Note your observations in the experiment’s data.
Sketch your model and label its trachea, lungs, and diaphragm.

What’s going on?

By placing a stopper in the top of the bottle and putting the stretched rubber balloon on the bottom, you have created an enclosed system. The tube at the top of the bottle is the only way for air to enter or exit the model’s lungs. Pulling down on the balloon’s knot reduced the air pressure inside the lungs. As compensation, air was pushed down into the tube to equalize the pressure. This caused the balloon lungs to expand. When you released the knot, the air pressure forced the air out of the balloons.

If you need more help with identification, the tube acts as the trachea, the balloons are the lungs, and the balloon with the knot at the bottom is the diaphragm.

Did you know that an average person breathes about 24,000 times each day? If you live to be 70 years old, that means about 600,000,000 breaths. Make them count!

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Testing Spit Samples

Friday November 18, 2011

Digestion starts in your mouth as soon as you start to chew. Your saliva is full of enzymes. They are a kind of chemical key that unlock chains of protein, fat, and starch molecules. Enzymes break these chains down into smaller molecules like sugars and amino acids.

In this experiment, we will examine how the enzymes in your mouth help to break down the starch in a cracker. You will test the cracker to confirm starch content, then put it in your mouth and chew it for a long time in order to really let the enzymes do their job. Finally you will test the cracker for starch content and see what has happened as a result of your chewing.

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Here’s what you need

1 package of soda crackers
1 5” pie tin
1 craft stick
1 0.5 oz bottle of iodine
1 pre-form tube
1 1 mL plastic pipette
water

Download Student Worksheet & Exercises

Here’s what you do

Take a cracker from the package and put it in the pie tin. Use your thumb to mash it up, making the pieces as small as possible. Add a small amount of water with the pipette. Mix everything up with the craft stick to make a mash of cracker.
Now fill the pipette with iodine. When iodine comes in contact with starch, it changes in color from reddish-brown to a dark blueish-black. Take the pipette and squeeze a few drops onto the cracker mash in various spots. Record what you see in your experiment data.
Take another cracker and chew it up for about 2 minutes. Do you notice any flavor changes as you are chewing? If so, note this. Be particularly aware of any sweet flavors.
Spit the mash into the pre-form tube once you have chewed for 2 minutes. Use the pipette of iodine to add a few drops of iodine to the chewed mash. Note any change in color. If there is no starch, the iodine will stay reddish-brown in color. If starch is present, you will see the color change to a very dark blue-black as it did in step 2. Record what you see in your data.

What’s going on?

This lab gives you a good idea of what happens in digestion, which starts as soon as food enters your mouth. Actually, the process can start even before this as your body prepares for food. Have you ever had a wonderful smell make your mouth water? This is your body’s way of getting ready to get to work digesting that delicious food.

Once you take a bite and the enzymes start to do their job of breaking large, more complex molecules into smaller particles. In this experiment, starch got broken down into simple sugars that your body could easily move around and use as fuel.

There are three sets of saliva-secreting glands in your mouth. They include a gland in the back of your throat called the parotoid gland, one in your lower jaw called the submandibular gland, and the sublingual gland which is under your tongue. The three work together to secrete up to 2 liters of saliva each day.

Exercises

What is the first step in the digestive process?
How does saliva help to digest food?
Name one or more of the main salivary glands and where they are located.

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Heart Rate Monitoring

Friday November 18, 2011

When you exercise your body requires more oxygen in order to burn the fuel that has been stored in your muscles. Since oxygen is moved through your body by red blood cells, exercise increases your heart rate so that the blood can be pumped through your body faster. This delivers the needed oxygen to your muscles faster. The harder you exercise, the more oxygen is needed, so your heart and blood pump even faster still.

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Here’s what you need

1 clock with a second hand
1 pencil

Download Student Worksheet & Exercises

Here’s what you do

While sitting quietly, place your first two fingers of one hand onto the wrist of the other hand. Feel for the pulse of your radial artery. Practice taking your pulse in intervals of 6 seconds.
After you have had some practice with the 6 second interval, take your pulse for this amount of time and multiply it by 10. The 6-second rate times 10 is your heart rate per minute. Record each for experiment data.
Now stand up and do 50 jumping jacks. When done, sit down immediately and check your pulse. Again, record the 6-second pulse rate, multiply it by 10 and also record the pulse rate per minute.
Finally, go outside and run around as fast as you can without stopping for 3 minutes. Again, immediately sit and take your pulse. Record the 6-second rate, multiply it by 10 and get your heart rate per minute.

What’s going on?

Exercising means your muscles need more oxygen. They ask your brain to tell your heart and lungs. When your heart gets the message, it starts to beat harder. Your lungs work harder, too. Together, your heart and lungs work as a team to provide the needed oxygen supply to your muscles. You can identify that this process is occurring by your heart rate increase and more rapid breathing rate.

Did you know that your heart is about the size of your fist? It is actually a muscle and it pumps more than a gallon of blood through your body each minute! An average heart rate is 70 beats per minute, but this can vary depending on age and fitness level. Based on 70 bpm, your heart will beat around 100,000 times per day. That’s more than 36 million beats a year!

Exercises

Explain how to take a pulse.
What units do we use to measure pulse?

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Detecting Carbon Dioxide

Friday November 18, 2011

An oxygen and carbon dioxide exchange takes place in your bloodstream. When you breathe air into your lungs it brings in oxygen, which is carried from your lungs by red blood cells in your bloodstream. Cells of your body use the oxygen and carbon dioxide is produced as waste, which is carried by your blood back to your lungs. You exhale and release the C02. You will study this exchange in today’s lab.

You will be using a pH indicator known as bromothymol blue. When you exhale into a baggie, the carbon dioxide will react with water in the bag. This reaction produces carbonic acid, which starts to acidify the water. More breathes in the bag equal more carbon dioxide, which equal a lower (more acidic) pH. You will notice the bromothymol will turn green when the pH of the water is right about 6.8 and it will turn yellow when the pH drops further to 6.0 and lower.

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Here’s what you need

- 1 1 oz. bottle of bromothymol blue
- 1 straw
- 1 resealable baggie
- 1 bottle of ammonia
- 1 pipette
- water

Download Student Worksheet & Exercises

Here’s what you do

Pour about 2 ounces of water into the baggie and add two capfuls of the bromothymol blue into it. Close the baggie well and swish the solution around inside it gently to mix. Note the color of the solution for your data record.
Open the baggie a tiny bit and put the straw inside, but DO NOT drink the solution! It could make you sick. Close the bag tightly around the straw and gently blow into the solution. Again, be careful not to suck on the straw.
Watch the color of the solution closely as you continue to blow into the solution and create bubbles of carbon dioxide gas. The color will change to a sea green color and then eventually it will change to bright yellow. Note each color change in your records.
You can return the solution to blue by slowly adding a base – such as ammonia – to the solution in the bag. Bleach will also work. Please ask an adult to help with this. Add one drop at a time, shaking after each addition to mix the solution. You will be able to observe when the pH starts to change back by the color of the solution. It should turn back to green and then to blue.

What’s going on?

Bromothymol blue will change color in a pH range from 6.0 to 7.6. It is an acid/base indicator. Its basic solution is at a pH of 7.6 or above – this is when it is blue. In acidic conditions, it will turn yellow – this is a pH of 6.0 or below. And when it’s in between the two, it will be the sea green color that you observed in your baggie.

Because carbon dioxide is a little acidic, when we breathe it out into the water and bromothymol blue solution its bubbles start to lower the pH. You saw a small change in pH with the sea green color, but as you continued to exhale and add carbon dioxide, the solution became more and more acidic. This eventually resulted in a pH at or below 6.0 and a bright yellow solution.

In order to exchange oxygen with carbon dioxide in your lungs, they have over 300,000,000 teeny little air sacs calls alveoli. In one minute, you breathe approximately 13 pints of air.

Exercises

What is pH and how it is useful?
What does a yellow color indicate with bromothymol blue?
Is CO₂ acidic or basic?

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Robotic Hand

Tuesday November 15, 2011

Your body moves when muscles pull on the bones through ligaments and tendons. Ligaments attach the bones to other bones, and the tendons attach the bones to the muscles.

If you place your relaxed arm on a table, palm-side up, you can get the fingers to move by pushing on the tendons below your wrist. We’re going to make a real working model of your hand, complete with the tendons that move the fingers! Are you ready?

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Here’s what you need:

five flexible straws
scrap of cardboard (at least as big as your hand)
five rubber bands
5 feet of string or thin rope (and a lighter with adult help if you’re using nylon rope)
hot glue with glue sticks
scissors
razor

Download Student Worksheet & Exercises

Exercises

What types of muscles are connected to our bones?
Which type of connective tissue connects our muscles to our bones?
What do extensor tendons in our wrist do?
What do flexor tendons do?

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Chemical Fingerprinting

Tuesday November 15, 2011

Did you know that the patterns on the tips of your fingers are unique? It’s true! Just like no two snowflakes are alike, no two people have the same set of fingerprints. In this experiment, you will be using a chemical reaction to generate your own set of blood-red prints.

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Here’s what you need

1 oz. bottle of baking soda or sodium carbonate (washing soda)
water
1 sheet of goldenrod paper
1 paper towel
1 magnifying lens

Download Student Worksheet & Exercises

Here’s what you do

Pour a couple teaspoons of the baking soda (sodium carbonate) into a cup of water. Swish your right index finger in the damp baking soda and then roll that finger on the goldenrod paper. This should leave a bright red fingerprint on the paper. Label it right index.
Continue the procedure for each finger on both hands to make a full set of prints. Be sure to label each fingerprint as you make it to identify which print goes to each finger. Don’t forget to make prints of your thumbs!
Compare your prints to the basic patterns in the guide. Check for features such as whorls or loops and label them appropriately on your prints. Use abbreviations such as A for accidental, PW for plain whorl, and DL for double loop.
After you have identified the dominant pattern on each of your fingertips, prepare a simple chart for each hand to record the data by finger.
When you are finished studying your own prints, ask a volunteer to let you make prints of their fingers.

What’s going on?

Goldenrod paper is made using phenolphthalein, a chemical that turns red when exposed to materials with relatively high pH. Baking soda (or sodium bicarbonate) is a base which has a pH of about 8.5. Rolling your baking soda covered fingers on the goldenrod paper creates a chemical reaction which produces a red fingerprint.

Exercises

What are the three main types of patterns on fingerprints? Describe each.
How do fingerprints have the potential to help solve crime?
Why does baking soda (or washing soda) show up red on the paper?
What kind of pH do bases have?
What kind of reaction do we see when the red fingerprints show up on the paper?

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Eyeballoon

Tuesday November 15, 2011

In this lab, we are going to make an eyeball model using a balloon. This experiment should give you a better idea of how your eyes work. The way your brain actually sees things is still a mystery, but using the balloon we can get a good working model of how light gets to your brain.

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Here’s what you need

- 1 biconvex plastic lens
- 1 round balloon, white, 9 inches
- 1 assistant
- 1 votive candle
- 1 black marker
- 1 book of matches
- 1 metric ruler
- Adult Supervision!

Download Student Worksheet & Exercises

Here’s what you do

Blow up the balloon until it is about the size of a grapefruit. If it’s difficult to inflate, stretch the material a few times or ask an adult to help you.
You will need an extra set of hands for this portion. Ask your partner to hold the neck of the balloon closed to keep the air in while you insert the lens into the opening. The lens will need to be inserted perpendicularly to the balloon’s neck. It will prevent any air from escaping once it’s in place. Like your eye, light will enter through the lens and travel toward the back of the balloon.
Hold the balloon so that the lens is pointing toward you. Take the lens between your thumb and index finger. Look into the lens into the balloon. You should have a clear view of the inside. Start to twist the balloon a little and notice that the neck gets smaller like your pupils do when exposed to light. Practice opening and closing the balloon’s “pupil.”
Have an adult help you put the candle on the table and light it. Turn out the lights.
Put the balloon about 20 to 30 centimeters away from the candle with the lens pointed toward it. The balloon should be between you and the candle. You should see a projection of the candle’s flame on the back of the balloon’s surface. Move the balloon back and forth in order to better focus the image on the back of the balloon and then proceed with data collection.
Describe the image you see on the back of the balloon. How is it different from the flame you see with your eyes? Draw a picture of how the flame looks.
The focal length is the distance from the flame to the image on the balloon. Measure this distance and record it.
What happens if you lightly push down on the top of the balloon? Does this affect the image? You are experimenting with the affect caused by near-sightedness.
To approximate a farsighted eye, gently push in the front and back of the balloon to make it taller. How does this change what you see?

What’s going on?

Okay, let’s discuss the part of the balloon that relate to parts of your eye. The white portion of the balloon represents your sclera, which you may have already guessed is also the white part of your eye. It is actually a coating made of protein that covers the various muscle in your eye and holds everything together.

Of course, the lens you inserted represents the actual lens in your eye. The muscles surrounding the lens are called ciliary muscles and they are represented by the rubber neck of your balloon. The ciliary muscles help to control the amount of light entering your eyes.

The retina is in the back of your eye, which is represented by the inside back of your balloon. The retina supports your rods and cones. They collect information about light and color and send it to your brain.

Exercises

How does your eye work like a camera?
How can you tell if a lens is double convex?
What is the difference between convex and concave?
Can you give an example of an everyday object that has both a convex and a concave side?
How can you change the balloon to make it like a near-sighted eye?
How can you change the balloon to make it like a far-sighted eye?

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Mapping your Tongue

Tuesday November 15, 2011

The tongue has an ingenious design. Receptors responsible for getting information are separate and compartmentalized. So, different areas on the tongue actually have receptors for different types of tastes. This helps us to separate and enjoy the distinct flavors. In this experiment, you will be locating the receptors for sweet, sour, salty, and bitter on the tongue’s surface.

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Here’s what you need

4 cotton swabs
5 wax cups
1 bag of black tea
1 bottle of red vinegar
2 packages of sugar
2 packages of salt
1 microwave
water
1 spoon
1 partner
1 blindfold

Download Student Worksheet & Exercises

Here’s what you do

1. Put 3 ounces of water into the first of the wax cups. Bring it to a boil in the microwave and have an adult help you add a teabag. This will make your bitter cup. Let it sit for 5 minutes. While it is steeping, you can prepare the other cups.

2. Fill the remaining cups with 2 ounces of water each. Prepare them as follows:

A.      For the sweet cup, add two packages of sugar to the warm water in one of the cups. Stir until well dissolved.
B.      For the sour cup, add 2 ounces of red vinegar to another cup and stir well.
C.      For the salty cup, put two packages of salt into the final cup. Stir until dissolved.
D.      The last step in cup preparation is to discard the tea bag that has been steeping in the first cup.

3. Now put the blindfold on your partner and have them stick out their tongue. Dip the first swab into the tea. Using the diagram as a guide, swab each area one at a time: A, B, C, and D. Ask your partner to identify the flavors as sweet, sour, salty, bitter, or can’t tell as you swab each individual area. Record your partner’s response for each area.

4.Your partner should rinse out their mouth with water after testing the bitter tea. Then test each of the remaining solutions, one at a time in the same manner.

What’s going on?

Humans can identify thousands of distinct tastes, but we only have four types of taste receptors. When you take a bite of something flavorful, your saliva starts to dissolve it immediately. This solution of flavor and saliva goes to your taste buds and is then interpreted by your brain as sweet, sour, salty, or bitter.

The taste buds have taste receptors which bind to the structure of certain molecules: sweet receptors recognize hydroxyl groups (OH) in sugars, sour receptors find acids (H+, such as the citric acid in a lemon), salt receptors respond to metal ions (like Na+ in table salt), and bitter receptors are triggered by alkaloids. These are bases which contain nitrogen. It’s interesting to note the location of the bitter taste buds – they are on the back of the tongue. Since many poisons are alkaloids, their bitter taste may actually trigger vomiting.

Anyone who’s had a stuffy nose can tell you that smell plays a big role in our ability to taste. This makes sense because we know that we can only really taste the 4 distinct true flavors of sweet, sour, salty, and bitter. Our nose works in partnership with our tongue to allow us to identify more complex flavors.

Exercises

How many different types of taste receptors do we have? What are they?
Can you still taste food when you have a stuffy nose?
Which taste receptors recognize the hydroxyl group?

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Scent Matching

Tuesday November 15, 2011

We now know that odor molecules are diffused throughout a room by the motion of air molecules, which are constantly moving and bumping into them. We also know that warm air moves faster than cold air, and that increasing the movement of the air (like with a fan) will increase the diffusion process.

In this experiment, we look at what happens when the odor molecules find their way into your nose. Your nose has smell cells located in a small area called the olfactory epithelium. We will use them here to match smells with other smells.

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Here’s what you need

- 10 small containers with lids
- 10 cotton balls
- 1 bottle of lemon juice
- 1 cup of black coffee
- 1 bottle of vanilla extract
- 1 bottle of cinnamon oil
- 1 bottle of soy sauce
- 1 black felt marker
- 1 assistant

Download Student Worksheet & Exercises

Here’s what you do

Take the lids off of the containers and number the first five with a 1 through 5. Mark the other five with A through E.
Put a cotton ball into each container. Start with the numbered containers and add some lemon, coffee, cinnamon, soy sauce, and vanilla. Record the smell for each number for reference.
Fill the lettered containers with the same liquids, but not in the same order. Be sure to record the material you have used for each letter.
Take the closed containers to your assistant. Ask them to match the scent in the first canister with the proper lettered container without opening the container. Given them permission to roll, drop, and shake the containers, but they can’t be opened. Note their response – are they correct?
Repeat step 4 for each of the containers until they all have been matched. Then check your recorded data and see how well your assistant did with matching.

What’s going on?

Everything here produces a distinct odor. The smells go into your nose where they are interpreted by the tiny hair-like smell cells in your olfactory epithelium. The smell cells work together to distinguish smells and then send the interpreted information to the brain for recognition.

We previously noted that humans have an average of 10,000,000 smell cells, but they aren’t all the same. You have about 20 different types and each detects a specific type of odor. The types work together and your brain translates their signals as a unique odor.

Exercises

What is the scientific name for sense of smell?
What is the name of the tissue which helps the brain to distinguish between smells?

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Detective Boxes

Tuesday November 15, 2011

In addition to looking pretty neat with all those loops and whirls, your fingertips are great at multitasking. The skin on them has a ton of receptors that help us to gather a lot of information about our environment such as texture, movement, pressure, and temperature.

This experiment will test your ability to determine textures by using touch receptors. You will use shoeboxes with holes cut into them to make texture boxes. Each box will have a textured surface that you can feel, but not see. Through the receptors in your fingers, you will determine whether the surface is rough, waxy, soft, or smooth.

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Here’s what you need

4 shoeboxes with lids
1 soup can
1 pencil
1 pair of scissors
1 sheet of sandpaper
1 sheet of wax paper
1 sheet of flannel fabric
1 sheet of plastic
1 glue gun
1 pair of gloves
partners

Download Student Worksheet & Exercises

Here’s what you do

Using the soup can as a guide, draw a circle at the end of a shoebox. Then use the scissors to cut out the circle.
Cut a piece of sandpaper to fit the bottom of the shoebox (a ruler might also be handy to get an exact measurement). Glue the sandpaper to the inside bottom of the shoebox. Put the lid on the box and label it as Box 1.
Repeat the first two steps for each of the boxes, putting the wax paper, flannel, and plastic in boxes 2-4. Be sure to label each.
Now ask a partner to reach into each box, feel the texture, and describe it as rough, waxy, soft, or smooth. Record their answer. Use undecided if they aren’t sure.
Once your friend has identified a texture and you have recorded their response, open the box so that you can both see what material they have evaluated. Be sure to note in your data whether your friend was correct with a Y or N. Repeat steps 4 and 5 for each of the boxes.
Have your friend leave the room or look away so that you can rearrange the box lids. Then give them the gloves to wear and repeat the test using gloved hands. Record the data and compare the effectiveness of gloved hands. Does this have an impact on the touch receptors?

What’s going on?

The fabric of the gloves interferes with the ability of our touch receptors to function fully. Our fingertips are feeling the fabric of the gloves on their receptors and this makes it difficult to perceive what they are touching through the gloves.

We have 5 different types of receptors. They are types of nerve endings in our skin and are connected to our brains.

The ones that respond to deep pressure are called Pacini’s endings and they are embedded deep in our skin.
Merkel’s endings detect moderate pressure.
Meissner’s ending respond to vibrations and light pressure.
Ruffini’s ending, which detect changes in temperature, can also respond to pressure.
Our pain receptors are called free endings.

Exercises

Name, in order, the three main layers of skin.
Which layer of skin contains the mechanoreceptors? Name two more items in this layer.
Name the five types of nerve endings and their specialization.

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Tasty Tastebuds

Tuesday November 15, 2011

Did you know that your tongue can taste about 10,000 unique flavors? Our tongues take an organized approach to flavor classification by dividing tastes into the four basic categories of sweet, sour, salty, and bitter.

For this experiment, you will need a brave partner! They will be blindfolded and will be attempting to guess foods. Relying only on their sense of taste, they will try to determine what kind of foods you are giving them.

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Here’s what you need

1 partner
1 blindfold
1 cup of water
1 plate
1 lemon
2 toothpicks
1 sugar cube
1 salty cracker
1 piece of dark chocolate
1 pencil

Download Student Worksheet & Exercises

Here’s what you do

(NOTE: Make sure your partner is not around for the first step!) Prepare a plate with a piece of lemon on a toothpick, a sugar cube, a really salty cracker, and a piece of dark chocolate, which will also be on a toothpick.
Blindfold your partner before they see the plate. Explain that you’re going to give them food samples. Their job is to taste each sample, one at a time, and then determine whether the food is sweet, sour, salty, or bitter. After they have provided a category, see if they can tell you the specific flavor of the food. They should use the water between samples in order to rinse their mouth and prepare for the next food.
Record data and observations for each individual food item. Be sure to list each food, your partner’s group classifications (sweet, sour, salty, or bitter) and what specific flavors that they note.

What’s going on?

When you put food in your mouth, saliva immediately begins to break it down. Saliva mixes with food and makes a solution, which then takes the food (and its flavor) to the taste pores. There, receptors determine the chemical structure and send this information to your brain, which then decodes and categorizes the taste. The exact nature of the secret code relayed between your taste receptors and your brain is still a mystery. Maybe someday you can help to figure out the science behind it!

Did you know that humans have about 7500 taste buds? That’s a lot compared to most chickens, which only have about 24, total. But it’s a pretty small amount compared to catfish. They have over 175,000 taste buds! Can you imagine what your favorite dessert might taste like if you had that many? I wonder if it would be a good thing, or maybe too much information. Perhaps we are better off with our own perfect number of taste buds!

Exercises

How does saliva help with tasting?
What helps to decode the chemical structure of a food so that the brain can determine its taste type?
Why do foods sometimes become less strong as we age?

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Detecting Temperature Changes

Tuesday November 15, 2011

This experiment has two parts. For the first half, you will mix two chemicals that will produce heat and gas. The temperature receptors in your skin will be able to detect the heat. Your ears will detect the gas at it vibrates and escapes its container.

In the second portion you will demonstrate a characteristic in a chemical reaction. For this experiment, it will be an endothermic reaction, which is the absorption of heat energy. This type of reaction is easy to notice because it makes things cold to touch. The chemical you will be using, ammonium nitrate, is actually used in emergency cold packs.

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Here’s what you need

1 measuring cup
1 bottle of calcium chloride
1 bottle of ammonium nitrate
2 resealable baggies
water

Download Student Worksheet & Exercises

Here’s what you do

Put about ½ cup of warm water in one of the baggies.
Add about a third of an ounce of calcium chloride to the water. Close the baggie and start to roll around the pellets with your fingers. As they start to dissolve, the chemical also starts to increase the temperature of the water.
Now dispose of these ingredients down the drain. Flush with lots of running water.
Open the ammonium nitrate and fill its cap with pellets. Put these in the second baggie.
Start to pinch the ammonium nitrate through the plastic bag and check for a temperature change. Does anything happen in the absence of water?
Now put a small amount of water (about room temperature) into the bag. Fill it about ¼ of the way full.
Hold the bottom of the bag with both hands and begin to rock it back and forth a bit. This should start to dissolve the pellets. With your hands on the water, you should start to note a temperature decrease. If this doesn’t work, roll the pellets around as you did with the calcium chloride.
When you are finished, you can pour the contents out on to brown spot of grass (because ammonium nitrate is a main ingredient in many fertilizers). Or if you would prefer, just empty the contents down the drain.

What’s going on?

Calcium chloride splits into calcium ions and chloride ions when it is mixed with water. As this occurs, energy is released in the form of heat. This is the same heat energy you felt when holding the baggie and rubbing the pellets.

Adding ammonium nitrate to water causes both its ammonium and nitrate ions to dissolve, which results in heat absorption as iconic bonds are broken. This is an endothermic reaction.

The point of both of these experiments is that the Ruffini’s endings in your skin are what allow the heat and/or cold data to be collected and sent to your brain for translation.

Your skin has many other parts in addition to its receptors. Some examples include hair, blood vessels, and sweat glands. Blood vessels and sweat glands respond to heat and cold, helping to control your body’s temperature. You are probably familiar with how sweat glands help to cool you down (evaporation), but how about blood vessels? As an example, if you run around outside on a hot day, your cheeks get red because the blood vessels on your skin’s surface have dilated, which brings more blood to the surface and allows the body to cool its insides a bit.

Exercises

Which chemical when mixed with water was an endothermic (absorbed heat and felt cold) reaction?
Which chemical resulted in an exothermic reaction (gave off heat)? Why does this happen?
What are ways that the human body can detect temperature?

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Rubber Eggs

Tuesday November 15, 2011

This lab has two parts. First, you will learn a bit about how specific chemicals react in a specific manner. And next, you will learn a bit of biology: the structure of bird bones and the minerals that compose them.

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Here’s what you need

- 4 fresh chicken wing bones, meat removed
- 1-16 oz. bottle of distilled white vinegar
- 2-12 oz. plastic cups
- 1 fresh egg
- 1 spoon

Click here to download the student worksheet.

Here’s what you do

Make sure all the meat and cartilage is gone. Check near the joints for soft, white-gray matter and clean it off. Now break a bone in half. What does the inside look like? Note the color and hardness for your data. Be sure to wash your hands well after studying the bones.
Pour some vinegar in a cup and gently place the bones in the solution. Add more to cover the bones, if needed. Put the cup in a spot where it won’t be disturbed for a few days. It will take a while for the vinegar to fully react with the bones.
Take a look at the egg and note its color and hardness in your experiment data. Now carefully place the fresh egg in the second cup and pour vinegar over it. Be sure to completely cover the egg. You will need to cover the egg or keep an eye on it. The vinegar will evaporate and will need to be replenished. This portion of the experiment will take around 24 hours.
Use the spoon to remove the egg after 24 hours has passed. Set it down and gently push on it. What happened to the part that used to be shell? Check your notes from the previous day and note any changes that have occurred in the color and hardness of the egg after it has been in the vinegar.
After a few more days, take the chicken bones out of the vinegar. Bend them and see what happens. Do they break as easily as they did the first day? Look at your data and compare the color and hardness of the bones now to how they looked on the first day. Record the changes you observe.

What’s going on?

Calcium is the mineral in both bones and eggshells that makes them hard. Putting the bones and egg in vinegar caused the calcium to begin to react. Vinegar leached calcium from both the bones and the shell, which caused their hardened structure to become weak.

Did you know that your bones and teeth contain 99% of the calcium in your body? About ¾ of your bones are compact, but the remaining ¼ of them is spongy. But do you think your bones or your teeth are harder? The second hardest material in your entire body is the compact, hard bone. Your teeth enamel is actually the hardest material.

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Water Lens

Tuesday November 15, 2011

Like sound, light travels in waves. These waves of light enter your eyes through the pupil, which is the small black dot right in the center of your colored iris. Your lens bends and focuses the light that enters your eye. In this experiment, we will study this process of bending light and we will look at the difference between concave and convex lenses.

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Here’s what you need

1 washer, 3/8 inch inside diameter
1 microscope slide
1 container of petroleum jelly
1 piece of newsprint with a lot of type
1 pipette, 1 mL
water

Download Student Worksheet & Exercises

Here’s what you do

Apply a little petroleum jelly on the washer’s flat side. NOTE: washers have flat and founded sides, so be sure you are putting the petroleum jelly on the flat side of the washer.
Put the washer, petroleum jelly side down, on the middle of the microscope slide. Twist the washer a bit to seat it on the slide and make a seal. This should keep the water in place.
Put the washer and slide on the newsprint. Fill the pipette with water. Use the pipette to slowly place water in the washer. Fill the washer until the water makes a domed shape. You have just made a convex lens!
Find a letter e on the newspaper and put the lens over it. Draw a diagram of what the e looks like through the convex lens.
Now use the pipette to remove water from the washer. Your goal is to create a dip in the surface of the water. Now find the same e and place your new concave lens over the letter. Draw a picture of what the e looks like through the new lens.

What’s going on?

You can see that a convex lens bends outward and a concave lens bends inward. What does this do to light?

In a convex lens, the domed surface means that if light waves come in through the flat bottom surface, they will be spread out, or refracted, as they exit the curved portion of the lens. But since a concave lens dips inward it creates the opposite effect. When light waves exit the concave surface, they are brought together. This makes images appear smaller.

The lens does all the focusing work but it is actually the shape of the eye that determines what you see. If you have a tall, oblong eye, you are far-sighted. And conversely, if your eyes are short and fat, you are near-sighted. In either case, the lenses are functioning properly but the actual shape of the eye needs a slight adjustment.

Exercises

What are the two main types of lenses?
How are the two main types of lenses shaped
How do the two main types of lenses work?

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Foggy Hands

Tuesday November 15, 2011

Skin has another function that it vital to your survival: temperature regulation. Being exposed to high temperatures causes your skin’s pores to open up and release sweat onto your body. This helps cool us off by the resulting process of evaporation.

Your pores will close in extremely cold temperatures. Also, the body stops blood flowing to the skin in order to conserve heat for the important vital organs and their processes.

In this lab, we study the moisture that your skin produces – even when you are not aware of it!

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Here’s what you need

1 gallon baggie
1 string, 12 inches long
1 assistant
1 clock

Download Student Worksheet & Exercises

Here’s what you do

Record a description of how moist your hand is prior to putting it in the baggie. This is at 0 minutes.
Put your hand in the baggie and ask your assistant to tie it closed around your wrist. No air should be able to get in or out of the baggie. Record the time for tracking purposes.
Check your hand every 10 minutes for a half hour. With each observation note the amount of moisture that has accumulated. Record your observations at 10 minutes, 20 minutes, and 30 minutes.
What do you think will happen if you go outside and run around with your hand inside the bag? Try it and see if it accelerates the process.

What’s going on?

Sweat glands are always producing moisture on our skin. Most of the time, we don’t really notice this process. By enclosing your hand in plastic, this moisture can’t evaporate as it normally would. The bag collects and condenses it.

It is interesting to note that your body can produce up to a gallon of water in extremely hot temperatures – 110 degrees Fahrenheit and higher. This is one of the reasons it’s so important to stay hydrated in extreme heat!

Exercises

How is sweat released from the body through the skin?
How does sweat help to cool the body?
What did you observe at the 30 minute mark in your experiment?
What is evaporation and how is it different from condensation?

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Finger Thermometers

Tuesday November 15, 2011

Your fingers have receptors which perform various jobs. In addition to touch, they can detect pressure, texture, and other physical stimuli. One specialized type of receptors is called Ruffini’s receptors. They are good at identifying changes in pressure and temperature. In this experiment, we will test their ability to distinguish between hot and cold temperatures. We are actually going to try and trick your Ruffini endings. Do you think it will work?

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Here’s what you need

3 glasses
1 Celsius/Fahrenheit thermometer
hands
1 clock with second hand
hot water
cold water
ice cubes (optional)
room-temperature water

Download Student Worksheet & Exercises

Here’s what you do

Place the three glasses in front of you on a table. They should be in a row: left, middle and right.
Put hot water from the faucet into the first glass on your right. Pour very cold water from the tap into the far left glass. You can even add a couple of ice cubes if you have them available. Finally, fill the glass that is in the middle with room temperature water.
Now use your right hand to hold on to the glass on the right with hot water. Really spread out your fingers and wrap them around the glass. Do the same thing with your left hand and the glass filled with cold water. Be sure to check the clock and leave your hands on the glasses for exactly one minute.
After one minute, take your hands and put them both on the middle glass. (You may need to stack one on top of the other if your glasses are narrow). Note the temperature you feel with each hand: hot, cold, or medium. You can use the thermometer to record the actual water temperature.
Now repeat steps 1-4. This time, switch the hot and cold glasses so that you are holding the hot water with your left hand and the cold water with your right hand. Compare these results with your initial results. Do both hands respond in a similar way or is one more sensitive that the other?
Some questions to think about:

Does the temperature of the middle glass feel warmer, cooler, or the same when you touch it with your hand that was holding the warm glass?
What does your hand that was touching the cold glass feel when it touches the middle glass?
What do you feel when both hands are on the middle glass?
Why do you think your hands are not the best instruments for determining temperature?

What’s going on?

Your hands are designed to adapt to temperature. Touching the warm glass relaxes the muscles of your hands, increases circulation, and enhances flexibility. When your hand touches the cold glass the cells on your skin’s surface begin to contract to minimize loss of heat and your hand becomes less flexible. Then, when you grab the middle can your hands get a bit confused. Relatively speaking, the middle glass feels warmer to the hand that was holding the cold glass and it feels cooler to the hand that was holding the warm one. The hands are still feeling the temperature, but your brain gets confused.

Did you know that our skin does not have receptors to indicated burning hot? This sensation is actually created by three different receptors which fire at the same time: pain, cold, and warm. This explain why to some people, very hot things actually feel cold. If you could prepare a group of alternating hot and cold metal bars, touching them with your fingers would be an odd experience. Your brain will think they are too hot to touch and will tell you to pull away your hand!

Exercises

Does the temperature of the middle glass feel warmer, cooler, or the same when you touch it with your hand that was holding the warm glass?
What does your hand that was touching the cold glass feel when it touches the middle glass?
What do you feel when both hands are on the middle glass?
Why do you think your hands are not the best instruments for determining temperature?
Which nerve endings help to detect changes in temperature?

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Disappearing Frog Experiment

Tuesday November 15, 2011

Your optic nerve can be thought of as a data cord that is plugged in to each eye and connects them to your brain. The area where the nerve connects to the back of your eye creates a blind spot. There are no receptors in this area at all and if something is in that area, you won’t be able to see it. This experiment locates your blind spot.

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Here’s what you need

- 1 frog and dot printout
- 1 meter stick
- 1 scrap piece of cardboard

Download Student Worksheet & Exercises

Here’s what you do

Print out the frog and dot and remove the dotted portion. Attach it to the piece of cardboard, which should have a matching portion removed. You can place the paper and cardboard on the meter stick at the notched area.
Now to locate blind spots. First, close your left eye. Look at the frog with your right eye. Can you see the dot and the frog? You should be able to see both at this point, but concentrate on the frog. Now slowly move the stick toward you so that the frog is coming toward your eye. Pay attention and stop when the dot disappears from your peripheral vision. At this point, the light hitting the dot and reflecting back toward your eye is hitting the blind spot at the back of your right eyeball, so you can’t see it. Record how far your eye is from the card for your right eye.
Continue to move the stick toward your face and at some point you will notice that you are able to see the dot again. Keep moving the stick forward and back. What happens to the dot?
Repeat steps 2 and 3 with your left eye, keeping your right eye closed. This time, stare at the dot and watch for the frog to disappear. Move the paper on the stick back and forth slowly until you notice the frog disappears. You have found the blind spot for your left eye. Be sure to note the distance the paper is from your eye.

What’s going on?

There are no light receptors in the area of your eye where the optic nerve attaches to your eyeball. This is your blind spot and if an image is in this spot, the light reflected off of it doesn’t get perceived by your eye. So you don’t see it!

Exercises

What did you notice about the vision of the student and the blind spot that you measured?
Why do you think it’s important to know where your blind spot is?

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Swallowing

Tuesday November 15, 2011

Peristalsis is the wavelike movement of muscles that move food through your gastrointestinal tract. The process of digestion begins with chewing and mixing the food with saliva. From there, the epiglottis opens up to deposit a hunk of chewed food (called bolus) into your esophagus – this is the tube that runs from your mouth to your stomach. Since the esophagus is so skinny, the muscles along it must expand and contract in order to move food down. In this activity we will examine that process.

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Here’s what you need

- 1 tennis ball
- 1 pair of old nylons
- 1 pair of scissors

Download Student Worksheet & Exercises

Here’s what you do

Cut away the control top portion of the nylons and remove the toe part as well (have an adult help you, if needed). You should now have a long piece of nylon.
Put the tennis ball in one end of the nylon “esophagus.” Start using both hands to move the ball down the nylon tube until it arrives at the other end.

What’s going on?

The esophagus is lined with muscles that work in waves, expanding and contracting to move food along it down into the stomach. These are very strong muscles: even if you ate upside down they would work!

In the grand scheme of the digestion process, the role of the esophagus is important, but relatively short. It takes about 10 seconds to move food from the mouth to the stomach, but the entire process of digestion can take up to 2 and a half days to finish!

Exercises

What is the tube called that connects the mouth and stomach?
What is the process called that moves food along the digestive tract and how does it work?
How long is food in the esophagus?

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Diffusion

Tuesday November 15, 2011

Everything living produces some sort of odor. Flowers use them to entice bees to pollinate them. We know that the tastes of foods are enhanced by the way that they smell. As humans, each of us even has own unique odor.

In this lab, we look at the diffusion of scents. They start in one place, but often end up spread around the room and can be detected by many people.

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Here’s what you need

- 1 onion
- 1 lemon
- 1 bottle of ground cinnamon
- 1 clove of fresh garlic
- 1 garlic press
- 1 pile of fresh coffee grounds
- 1 kitchen knife
- 1 cutting board
- 1 variable-speed fan
- 1 clock with a second hand

Download Student Worksheet & Exercises

Here’s what you do

Start in a room big enough so that you can prepare the foods at one end and your friends or family members can be at the other end, but positioned so they can’t see what you’re doing.
You will need a simple map of the room showing the locations of your partners, the source of the odor, and the fan (which will help with the scent diffusion). Create a new map for each smell.
Turn on the fan and begin with the onion. Ask an adult to help you with cutting the onion into several small pieces. Be sure to hold the chopped pieces up in front of the fan. Ask your partners to raise their hands when they smell the onion. If they don’t smell it, they can leave their hands down. Note on the onion map where its smell is detected. Indicate with a line the farthest area where the onion is smelled. This is its leading edge.
Check in with your partners once per minute for five minutes. Ask them to raise their hands and repeat the process of noting the areas where the smell is detected. Each time you check, draw a line to indicate the farthest area the smell reaches. This will give you an idea of how fast and how far the smell diffused.
Repeat steps 3 and 4 with each item: cut and smash the lemon and press the garlic. Which odors travel the farthest? Which ones travel the fastest?

What’s going on?

Many factors affect how quickly odors diffuse. First, the air is constantly moving. As the air molecules in the room are colliding with each other (and with the odor molecules) they help to move the smells farther through the room. Second, the fan makes a huge difference. It accelerates the natural process of air and odor molecules and moves them much farther and faster than they would go otherwise. Finally, the air temperate plays an important role. If the temperature is higher, the air and odor molecules will move faster.

As humans, we can boast about 10,000,000 smell cells in our noses. This seems pretty impressive…unless you compare us to canines. Dogs have over 200,000,000 smelling cells in their nasal cavities!

Exercises

Which odors travel the farthest?
Which ones travel the fastest?
Why do we use the fan?
Does air temperature matter?

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Cooling and Heating

Tuesday November 15, 2011

In this experiment, we will continue to explore Ruffini’s endings in your skin. We also look at your body’s ability to detect temperature and regulate its own temperature. You will study how the body cools and warms itself.

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Here’s what you need

1 bottle of rubbing alcohol
1 cotton ball
1 liquid crystal thermometer strip
1 cotton glove

Download Student Worksheet & Exercises

Here’s what you do

Position the thermometer strip on the back of your hand. Give it a moment to register the temperature of your body. Record this temperature as a base reading for your data.
Put some rubbing alcohol on a cotton ball. Now use the cotton ball to wipe the alcohol on the surface where you took the reading, right on the back of your hand. Quickly put the thermometer strip right back on the spot where you have put the alcohol and take another reading. Note the temperature in your records.
Now put the glove on your hand and run around in the yard, do some jumping jacks, or find another way to be physically active for 3 minutes. When you have worked up a sweat, come back to the experiment area. With your hand still in the glove, put the liquid crystal thermometer on the back of your hand where you took the first reading. Record this temperature information in your data records.
Finally, take off the glove and observe your hand. Can you tell that your sweat glands have been working? If so, have they been very active or just a little active?

What’s going on?

Your body likes to keep your temperature in equilibrium, which is a state of balance. It works hard to regulate your temperature and avoid any sudden changes that could be harmful. Constant and predictable is your body’s goal and it uses your skin to help.

When you are cold, blood flow to the skin is reduced in order to help stem the loss of heat. Your hair also stands on end in an error to trap air next to the body and help insulate it…although this doesn’t work very well for most of us! This is a more effective tool against heat loss with much furrier mammals.

In order to cool you down, skin can use some of your three million sweat glands. Sweat absorbs and displaces extra heat and can also close openings to cells on the surface to avoid excess gains in heat.

Your data in the lab should have simulated the effects of body temperature in three different conditions: equilibrium, excess cold, and excess heat.

Exercises

What is equilibrium?
How does equilibrium relate to body temperature?
How does our body help to cool us down?

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How Does the Eye Work?

Tuesday November 15, 2011

The eye is a complex structure that detects and focuses light. Light first enters the eye through the cornea, a clear protective layer on the outside of the eye. The pupil, a black opening in the eye, lets light in. In dark rooms, the pupil will become larger, or dilate, in order to let in more light. If the room suddenly becomes bright, the pupil will become smaller. The pupil is surrounded by the brown, blue, grey, or green iris.

After passing through the pupil, light goes to the lens which, like a hand lens, is a clear curved structure that helps focus light on the retina, in the back of the eye. The retina is where the rods and cones are found.

This video is an old instructional film shown to pre-med students in the early 50s you might enjoy watching:

Visual Reflex

Tuesday November 15, 2011

Voluntary nerves are the ones that are under our direct control. Others, called involuntary nerves, are under the control of our brains and create involuntary reactions.

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Here’s what you need

- 1 metric ruler
- 5 volunteers

Download Student Worksheet & Exercises

Here’s what you do

You will begin by testing your visual reflexes with the help of an assistant.
Hold your right elbow at your waist. Position your arm so that it is parallel to the floor. Make a space of about an inch by holding your thumb and forefinger apart. Ask your assistant to hold the ruler vertically, above your thumb and finger.
Your job is to focus on the ruler. Your partner will unexpectedly release it so that it begins to fall. You will attempt to catch the ruler as soon as you possibly can.
Repeat the experiment 5 times, recording the time it takes to catch the ruler each time for your data. Use the times you record to find your average time.
Try this experiment for 5 additional people. Find the average reaction speed of each person and the average speed of the group as a whole.

What’s going on?

This experiment is an example of a voluntary response. Your eyes see the ruler moving and tell your brain, which then tells your fingers to close quickly. This all happens very fast, but involuntary reflexes can be much faster! You may notice in this activity that the ruler falls over half of the way through your fingers before you can stop it. This is partly because of the communication from eyes to brain to fingers. Although the nerves transmit very quickly, the transmission time can still take a little while.

There are two separate systems at work here: the central nervous system is your brain and spinal column and the longer nerves branching out from the spinal cord to every part of your body is the peripheral nervous system. They work in conjunction to coordinate your actions.

If you lines up all of your nerves, end to end, they would stretch for miles and miles: an average length is about 47 miles of nerves. The longest is the sciatic nerve. It goes from the bottom of your spine to the bottom of your foot.

Exercises

What is the voluntary response in this experiment?
What is an involuntary response in your body? Give an example.

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PhotoReading

Tuesday November 15, 2011

Does it sound impossible to read 25,000 words per minute with a 75% comprehension? Not at all! I learned how to photoread using this cool technique developed by Paul Scheele that I am going to share with you. You’ll be able to digest entire textbooks, articles and newspapers that have been piling up, or read hundreds of emails just a matter of minutes. And no, it’s not ‘speed reading’, and it’s not ‘photographic memory’ either. It’s not magic – but it really works! Anyone who can read a book can learn how to do it.

Most folks read the same way they were taught in grade school – at about 200 words per minute with a 55% comprehension level. And sadly, most remain at this level while stacks of untouched newspapers, magazines, mail, articles, books and reports clutter your living space. When will you ever find the time to read for pleasure with so much to sift through? So many people are trying to cope in the information age using the same reading skills they learned in grade school!

The challenge isn’t whether photoreading is possible, but rather how to incorporate photoreading into your everyday activities, just like eating and sleeping. After I learned how to photoread, I felt much more on top of things in my life, because I had the information I needed to make effective decisions. While I used to spend days reading science textbooks and technical journals, now I only spend minutes per document and I have a clear desk feeling at the end of the day, both at my office and in my home. I can keep up with all the latest daily news in 10 minutes.

The main presumption when picking up a book is that you must read every word in order to understand its message. Not only that, but the book must be read all at one speed: painfully slow.

You know from experience that you don’t have to read every word to get the gist of what a paragraph is talking about. Nor do you have to read an entire textbook at the same speed. We’re going to learn how to super-read, rapid-read, and photoread. Think of it as giving your car a new set of gears: you only had first gear available in your car, and now I’m going to show you how to use 2nd gear, 3rd gear, and overdrive.

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The basic idea behind photoreading is this: you have to give up the idea that you must read every single word in a book in order to know what’s inside the book. That’s going to be a challenge for a lot of folks who grew up like I did, when my brain insists on reading every word and even re-reading it because I felt I didn’t read a sentence right. Photoreading skips over this entirely because the basic idea behind it says that you don’t have to know the book consciously, but rather subconsciously, in order to know what’s inside.

You’re probably a bit skeptical now (I know I was at first, too, so it’s a good sign), especially when I saw someone photoreading a 450-page book that was upside-down and they were flipping through the pages backwards! Yes, he really had an 85% comprehension on the textbook, as proven on his exam two hours later.

So now you are ready for the mechanics. Basically, here’s how it works:

First, figure out your basic purpose for reading the material. Is there a question that this book can answer for you? What is your intent behind wanting to reading this book? Photoreading won’t work if you do not have a purpose for reading. It’s important to realize that photoreading is not the same thing as reading for pleasure (which you will be able to do a lot more of, because you won’t have stacks of textbooks and emails to read through anymore!).

After you have a clear sense of why you are reading the material and the question(s) it will answer for you, it’s time to get into a resourceful, alert, relaxed state. It’s best to start photoreading before you go to bed, because your conscious mind is already getting ready to shut off… which is exactly what we want to do. When we photoread, we want to bypass the logical conscious mind and dump all the information directly into the subconscious mind. (This is the part where you’ll have to un-learn that you must read every word.)

After you’ve photoread a book at a good rate (usually one or two seconds per page), you now have the contents of the book in your mind, so now you will earn how to build a bridge between your subconscious and your conscious so you have access to the information.

Here’s a video that shows the actual EEG brain scan as a brand-new student photoreads a book. Electroencephalography (EEG) is how scientists record the electrical activity by measuring voltage fluctuations (which come from neurons of the brain). When you do an activity, you’ll see different wave patterns of the brain’s spontaneous electrical activity. For example, delta waves are seen most often in babies and also when adults are asleep. Theta waves are seen more often in young children, relaxed or sleepy adults, and also in meditation.

Okay – are you ready to really learn how to do this? Here are the basic steps on how to photoread:

State Your Purpose In order to read effectively, you’ve got to have a clear sense of purpose about why you’re reading the material in the first place. Do you want an overview of the main points? Ideas for inspiration? Learn how to fix the sink? Keep your purpose at the front of your mind as you begin this process. You must state your purpose everything you read to engage your concentration. I’ll repeat this purpose over and over throughout this entire process so it stays at the front of my mind.
Get into the Ideal Reading State When the body is relaxed and the mind is alert, you are more able to comprehend what you are reading and recall it later when you need it. Place your reading material in front of you, relax by closing your eyes, and sit as you would in a state of positive expectancy. I usually say something to myself like this: “During the next few minutes, I will read this book for ideas to help improve my understanding of astronomy.”
Preview When reading effectively, you must take a big picture perspective at first. Take 60 seconds to look over the material, figure out if it’s even worth reading, and make the decision on whether to continue or look for something else to read. I usually look over the table of contents, or if it’s an article I look at the headers, bold type, first and last paragraphs. I’ll also restate my intention to read the material as I look it over.
PhotoFocus This is where you get your ind in a resourceful state. There are many different ways to do this, and I’ve shown you my favorite way in the video (seeing the ‘hot dog’ and the ‘blip page’), but you will want to find your own method as you play with these ideas.
PhotoRead Maintain a steady state while flipping through the pages. Usually I will repeat over and over something rhythmic (like “all I need is within this book…” or even “keep the state and see the page…” in order to keep the flow going. I often can’t turn the pages fast enough! At the end, close the book with a sense of mastery over the content, and think something like this: “I am curious as to how many ways my mind can demonstrate that this information is available to me.”
Postview This is where you go back through the book for only about 10 minutes, looking at the text on the covers, the index (especially for words that have a ton of pages listed after them), bold or offset text, previews, summaries, figures, charts, and graphics. I also look for 10-20 trigger words that leap out at me and begin to formulate questions that I want answered. I survey the book by looking only at one page every 20 or so, looking at any interesting sections that catch my attention that may relate to my purpose. Although it’s tempting to get sidetracked and start reading deeply, I resist and keep moving through the book. I want to get the maximum benefit from every second I spend reading the book, and if I slow down too soon, I usually end up slugging through pages and pages that don’t serve my original purpose.
Activate This step is easy: just walk away from the material for 20 minutes to a full day. By taking a break, you are letting your mind work with the new content. After the break, review the questions you formulated from step 6 (above) and the trigger words. It’s important to not expect immediate results right away. Your purpose now is to alert your brain to the questions you wanted answers to, and to give your mind the time it needs to get your answer to you. Stay relaxed and curious, and you’ll find that bridge between your conscious and subconscious become sturdier the more questions you ask.
Comprehension This comes in layers, so you’ll want to play around with different methods to find the ones that work best for you. Restate your purpose for reading as you ‘super-read and dip’. Super-reading is done by rapidly moving your eyes down the center of each page, looking for meaning using a softer gaze. When I first tried this, I was amazed how much my peripheral vision picked up on the sides! I got so distracted that it was hard to learn how to super-read. If a sentence grabs you, go in and ‘dip’ – read a sentence or two – and go back to super-reading again. You ‘dip’ whenever you have a ‘hunch’ or something catches your attention.
More on Comprehension By the way, learning to trust myself was one of the hardest things for me at this stage! My mind would often say something like this: “Stop! Go back!! You missed a word… you are not reading carefully enough! Now go back and do it right!” By just taking a breath and moving on, I wouldn’t get stuck there. I also learned just to wildly dance around the page, like a bug on the surface of a pond, just zooming around until I hit something worthwhile. This works best if you first read the topic sentence of a paragraph, then zigzag your eyes quickly over all the words in the paragraph. You’ll be able to quickly understand the main points. If you still can’t, go on to tread the last sentence.
Mind Map This is totally optional, but I found it to be a very fast and efficient way to get long-term retention and synthesizes the information acquired by super-reading and dipping. You can think it through or write it out on paper – whichever works best for you. First, the core idea starts at the center. Supporting ideas are written on connecting lies that radiate out from the core concept. These ideas are trigger words or key terms (three words or less each). Draw images next to the words when you can, and colorize the map ti indicate how you’ve organized the material. There are several great books on this, including Mind Map by Tony Buzan and Mind Mapping by Joyce Wycoff.
Rapid Read Often you know exactly which parts of the book you want to study in more detail, so rapid reading is used after you super-read and dip, especially if a chapter is super-important or highly technical that you really need more time with it. To rapid read, move swiftly through the text, taking as much time as you need. When you have already read a paragraph or page during one of the previous steps (above), zip past it. When you recognize the information as understood or redundant, zip past it. Anything unimportant, just zip past it. You’ll find you need to move slower when the text contains unfamiliar information or you find something important you want to explore in detail. The end result is that you move through the book at different speeds, depending on the importance and your prior knowledge of the content. Just keep moving – don’t get stuck or sidetracked. If something doesn’t make sense – don’t re-read it.. keep going and assume that you’ll pick it up somewhere else.

Why This Works There’s an important distinction between reading for relaxation, for information, for understanding, and for challenging and deepening your mind. Reading for pleasure is easy – we all learned how to do this in grade school. But how do we handle the rest?

I want you to watch a video from Paul (the person who first developed this idea) on the basics. This video below was taken from his infomercial about his program. In the video above, I show you the basics so you can get started right away. Watch this video below so you have a general idea about what photoreading is:

Elementary is the kind of reading we learn how to do when we first learn to read. The question we ask our mind at this stage is: What does the sentence say? That’s all we want to know. Unfortunately this is where a lot of us remain when reading everything. In fact, our current educational system stops here and doesn’t teach kids about the next three reading levels!

Inspectional reading is where you scan the page and read superficially. This is useful when you want to get a general idea of what a text is about and what kind of information it contains so you can decide if this is something you want to spend time reading. Ever read an entire article and reached the end with the feeling that the whole thing was an entire waste of time? If you have read inspectionally, this would have saved you time up front.

Analytical reading is when you thoroughly go through the material. This is when you are highly active in getting into the book, making the book your own. When you really want to understand something you read analytically. Francis Bacon once said: “some books are to be tasted, others to be swallowed, and some few to be chewed and digested.” Analytical reading is when you are chewing and digesting it.

Syntopical reading is when you take on several books on the same topic in order to put together the ideas into a new one that can’t be found in only one book. This is where you make new connections and coming up with new insights.

These four types of reading were defined back in the 1940s… and yes, we’re still mostly doing only the first kind. However, there is a fifth type of reading: Photoreading. This is where we incorporate all four of these ideas together in one fell swoop, and we do it quickly because we’re also engaging how the mind truly learns and absorbs material.

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Camera Eyes

Tuesday November 15, 2011

Your eyes have two different light receptors located on the back of the eyeball. These are the rods, which see black, white and grays, and the cones, which see color. In order to adapt to the dark, our eyes make a chemical called visual purple. This helps the rods to see and transmit what you see in situations where there is little light.

Your pupils also increase in diameter in the darkness. This allows for a slight increase in the amount of light entering your eye. This combination of visual purple and more light makes it possible for you to see in darker situations.

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Here’s what you need

- 1 dark room
- 1 light switch
- 1 partner
- 1 pencil

Download Student Worksheet & Exercises

Here’s what you do

Turn out the light in a darkened room and give your eyes about 5 minutes to get used to the darkness.
After your eyes have had a chance to acclimate to the low-light conditions, it’s time to get to work. Try to draw a picture of your assistant’s eye. Pay particular attention to how the pupil looks in the darkness.
Now turn on the light while still observing your partner’s eye. What happens to their pupil?
Draw another picture of your partner’s eye with the lights on. Again, pay special attention to the pupil.

What’s going on?

As you flip the light switch on, your partner’s brain realizes that there is a lot of light entering the rods and cones, so it restricts the size of the opening (your partner’s pupil) in order to limit the light. You might notice this on a sunny day if you go from a dark movie theater into the bright sun. It can actually hurt for moment, and makes you squint until your eyes have a chance to adjust to the brightness by reducing the size of your pupils.

Exercises

How does the pupil adapt to light conditions?
What are the two special photoreceptors called and where are they located?
Which photoreceptor is used to help us see in the dark?

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Human Levers

Monday November 14, 2011

Levers are classified into three types: first class, second class, or third class. Their class is identified by the location of the load, the force moving the load, and the fulcrum. In this activity, you will learn about the types of levers and then use your body to make each type.

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Here’s what you need

- 1 body

Download Student Worksheet & Exercises

Here’s what you do

In a first class lever, the fulcrum is in the middle. The load and effort are on opposite sides with the fulcrum between them. A familiar example of a first class lever is a see saw.
A second class lever has the fulcrum on one end, the load in the middle, and the force on the end opposite the fulcrum. A wheelbarrow is a good example of a second class lever.
Lastly, a third class lever has a fulcrum on one end and the load on the opposite end. The force is applied in the middle in this type of lever. A golf club is an example of a third class lever.
Use the photos to identify the levers of each type in your body.

What’s going on?

Only read further if you have had an opportunity to identify the levers in the pictures. Spoilers below!

Your head moving up and down on your spine is an example of a first class lever. Your neck joint in the middle is the fulcrum, with load and effort on either side. In this example, load and effort switch depending on whether you are moving your head up or down.

Standing on tiptoe is an example of a second class lever where your toes are the fulcrum. The effort, or force, is in your heels – they are lifting your body up. And the resistance is located between your toes and heels.

This leaves us with bicep curls, which are an example of a third class lever. Your elbow serves as the fulcrum, the bicep is the force, and the weight in your hand on the end is the load.

Just for fun, did you know your knee is the largest joint in your whole body? It connects your femur, the largest bone, to the bones of your lower leg. Your smallest joints are the anvil, hammer, and stirrup in your inner ear.

Exercises

Draw a diagram of a first-class lever. Where in your body is this type of lever?
Draw a diagram of a third-class lever. Where will you find this?
Draw a diagram of a second-class lever. Can you give an example of this type of lever in the real world?

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Sound Speed

Monday November 14, 2011

Sound has the ability to travel through the states of matter: solids, liquids, and gases. In this experiment we will study the movement of sound through these three states.

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Here’s what you need

- 3 baggies, resealable
- sand
- water
- air
- 1 desktop
- 1 spoon
- 1 partner

Download Student Worksheet & Exercises

Here’s what you do

Fill each bag two-thirds of the way full with each material. You should have one bag with sand, one with water, and one with air. Seal each baggie well.
Put the baggies on the desk or on a table. Note the density of the materials. Which is most dense, medium, and least dense?
Place your ear down on the first baggie that is filled with sand. Have your partner use the spoon to tap the table. Listen for the sound through the bag of sand.
Repeat step 3 with the baggie full of water and then the bag of air. Compare what you hear through each state of matter. Rank the tapping you hear through the solid, liquid and gas in order from loudest, to medium, to quietest.
When you have completed the tapping portion of the experiment, hold the bag of sand up to your ear. Have your partner speak to you through the baggie.
Repeat step 5 with the bag of water and again with the baggie of air. Note the clarity of the speech you hear through each bag. Rank each bag from loudest, to medium, to quietest.

What’s going on?

Sound is made by waves travelling through the air. They pass their energy along to the matter through which they are traveling. But now you know that sound doesn’t just travel through the air. Molecules in water are closer together than air molecules, which makes it much easier for them to bump into one another. So the speed that sounds travel through liquid is actually faster than it travels through the air, and the sounds travel further as well. Sound travels fastest of all in solids because the molecules in this state of matter are very densely packed together. Solids pass sound much farther and at much greater speeds.

If there is no matter to bounce their energy along, sound waves can’t really form. So once you leave earth’s atmosphere, there isn’t any sound!

Exercises

What is density?
Put these in their general order of density: liquid, gas, solid.
Which material passes sound waves along farther and faster?

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Sound Matching

Monday November 14, 2011

You know that sound comes from vibration which are picked up by the pinna (external part of the ears). Then the vibrations vibrate your tympanic membrane, which in turn vibrates the ossicles and then the cochlea. The cochlea sends information through the auditory nerve and sends it to the brain, which recognizes it as sound.

In this lab, you will testing your ability to sort and match different sounds.

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Here’s what you need

- 10 film canisters (for 53 mm film rolls)
- beans
- rice
- sawdust (or pencil shavings)
- paperclips
- pennies
- 1 black, felt marker
- assistant

Download Student Worksheet & Exercises

Here’s what you do

Take the caps off the canisters. Number half of them 1 to 5 and mark the others with A through E.
Prepare your experiment while your partner is out of the room. Fill five of the numbered containers with one of the materials. Note which canister contains each material for data records.
Next fill the lettered containers. Be sure to record which container contains which material for reference.
When the contents have been noted and the lids all replaced, bring in your partner into the room. Ask them to match the sound of the item in the first canister with one of the lettered containers. They can shake, roll, and even drop the containers, but they can’t take off the lid. Note the answer they give.
Repeat step 4 for the rest of the numbered containers. Remember to record the responses. When the canisters have all been matched, take off the lids and see how well they did.

What’s going on?

Objects produce distinct sounds when they vibrate. These differences can sometimes be distinguished by your ears. If you partner has good ears, listening closely and then correctly matching the contents was probably an easy task.

Now to share a little more about the cochlea: you know it ultimately receives sounds and sends signals to the brain. It is a small organ shaped like a spiral. It’s filled with fluid and tiny cells which are shaped like hairs. These hairlike cells convert the vibrations from sound into signals that can travel the auditory nerve up to the brain. The tiny cells are quite sensitive. They can actually be damaged by extremely loud noises, so remember to protect them with earplugs if you will be exposed to very loud sounds.

Exercises

What are the tiny bones in the ear called?
Name some other parts of the ear.

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Sound Whackers

Monday November 14, 2011

Have you ever held a plastic ruler over the edge of a desk or table and whacked the end of it? If so, you would notice a funny sound. This sound changes if you change the length of the ruler that is hanging over the edge. The sound you hear is made by the ruler’s vibrations.

In this lab, we begin to learn about sound. You know it is collected and deciphered by your ears, but did you also know that all sound is made when something vibrates? It could be a guitar string, vocal chords in your throat, or a plastic ruler that is hanging over the edge of the desk: vibrations make sound.

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Here’s what you need

1 desk
1 metric ruler

Download Student Worksheet & Exercises

Here’s what you do

Place the ruler on the desk at the 20 centimeter mark. Hold the portion of the ruler that’s still on the desk down very firmly with one hand. Press down the portion of the ruler hanging off the desk with the other hand. Now let it go. The ruler should begin to vibrate up and down while producing a strange sound.
Now rearrange the ruler so that it is placed at the 15 centimeter mark and give it a thump. What happens to the pitch this time? Is it higher or lower now that the overhanging portion is shorter?
Make sure you try the ruler at 5 centimeters, 10 centimeters, 15 centimeters, 20 centimeters, and 25 centimeters. Listen each time and place the lengths in order from highest to lowest pitch.
Finally, put the ruler at the 25 centimeter mark, with just 5 centimeters on the table and the rest hanging over the edge. Give it a whack and while it’s vibrating, slide the ruler back across the edge of the table to make the overhanging portion shorter and shorter. What happens to the sound?

What’s going on?

The overhanging portion of the ruler is the portion allowed to vibrate. This determines the sound’s pitch. When a short piece is hanging over the edge, a high pitch is made. And when the length is longer, the pitch is lower. This is what happens with all vibrating objects and is a function of their wavelengths.

Did you know that the tiniest bones in your body are found in your ear? They are called ossicles and include the hammer, anvil, and stirrup. They are located just behind your eardrum and collect the vibrations that come into the ear canal and hit your ear drum. When your ear drum begins to vibrate, the tiny bones vibrate as well. This causes your cochlea to vibrate as well, and it sends a signal to your brain for it to interpret.

Exercises

How is sound made?
How do you change the pitch of the ruler?

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Big Ears

Monday November 14, 2011

How do you think animals know we’re around long before they see us? Sure, most have a powerful sense of smell, but they can also hear us first. In this activity, we are going to simulate enhanced tympanic membranes (or ear drums) by attaching styrofoam cups to your ears. This will increase the number of sound waves your ears are able to capture.

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Here’s what you need

- 2 styrofoam cups, 12 oz.
- 2 styrofoam cups, 32 oz.
- 1 pair of scissors
- 1 kitchen timer

Download Student Worksheet & Exercises

Here’s what you do

Set the timer and put it on a table or desk. Walk about 6 feet away and face the timer. Listen for the ticking sound. Now, turn your back on the clock so that you are facing the other direction. How has your ability to hear the ticking changed? We can increase the sounds you hear by using the cups.
Get an adult to help with cutting the cups. They will hold one of the smaller cups with one hand and make a cut about an inch (3 cm) from the rim toward the bottom of the cup.
Draw a circle at the end of the cut that is about the size of your ear where it attaches to your hear. Cut out the circle.
Repeat steps 2 and 3 with the other 12 oz. cup. Carefully put them on your ears with their openings pointing forward. You have just added to the size of your ears and they should be able to collect more sound vibrations. Try listening to the timer now with the cups on your ears.
Now repeat steps 2 through 4 with the larger cups. Set the timer one more time and listen to the timer. Compare what you hear with what you heard with your unenhanced ears, and what you hear with the 12 oz. ears.
On a scale of 0-10, how much did the cups improve what you were able to hear? Note where you would place both the 12 oz. cups and the 32 oz. cups on the scale if 0 is the starting point equal to what you can hear with your own ears.
Repeat step 5 with the bag of water and again with the baggie of air. Note the clarity of the speech you hear through each bag. Rank each bag from loudest, to medium, to quietest.

What’s going on?

Hearing is based on movement. The initial process involves the actual waves coming toward your ear, which are funneled inside to your tympanic membrane.

In this experiment we focused on the initial funneling process. This is done by the visible, external part of your ear, known as the pinna. By making the pinna larger, you also increased their ability to pick up sound vibrations. This enabled you to hear much more, and at louder levels.

The pinna also help to determine the direction from which sound is coming. If a sound is coming from the left, your left ear hears it a little bit before the right. This lets your brain know where the sound originates.

Exercises

Which part of the ear is this experiment testing?
What happens when you change your variable in this experiment?
Did this experiment change your ability to detect which direction a sound came from?

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Ewww… Earwax!

Monday November 14, 2011

It may seem like walking across a balance beam and listening to your favorite song are very different activities, but they both depend on your ears. Ears are the sense organs that control hearing, which is the ability to detect sound. Ears also sense the position of the body and help maintain balance when you walk a balance beam or ride a bike.

Imagine a pebble being dropped into a lake. Waves of water go off in all directions. A similar thing happens when a car driving down the street honks its own. Waves go off from the car in all direction. The difference is that these are not waves of water, but instead are sound waves, which travel through the air. If you are nearby, some of those sound waves make it to your ear.

Here’s a video that shows you how everything works together so you can hear:

The pinna, or outer ear, which is the part of your ear that you can see, gathers up some of the sound waves, sends them down the ear canal, and eventually they strike the eardrum. The eardrum is a thin membrane that vibrates like a drum when the waves hit it. The vibrations pass three tiny bones, called the hammer, anvil, and stirrup, as well as a membrane called the oval window, causing them all to vibrate.

From the oval window, the vibrations go to the cochlea, liquid-filled space lined with hairs. The vibrations make waves in the cochlea’s liquid, just like waves in a pond, causing the hairs to move. The movement of the hairs sends a nerve impulse through the auditory nerve to the brain. The brain interprets the message and “tells” you what you have heard.

This video is an old instructional film shown to pre-med students in the early 50s you might enjoy watching:

Along with hearing, the ears play a major role in balance. Inside the ears are semicircular canals which are lined with hairs and full of liquid. When the body moves in one direction, the liquid in the semicircular canals move, causing the hairs to move. This sends a message to your brain, which gives instructions for the body’s muscles to contract or relax. This keeps you balanced.

There’s a cool video of a camera going inside the ear… watch out for the wax!

Tricking your Muscles

Sunday November 13, 2011

The muscles in your body allow you to move. In this lab we will do two quick experiments to explore how your muscles work.

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Here’s what you need

1 partner
1 clock with second hand

Here’s what you do

Hold your arm out straight. Ask your partner to push down on it while you try to raise it up against the pressure they are applying. Both of you should apply steady pressure in opposite directions for 30 seconds.
After half a minute, your partner should let go. Try to relax your arm. What happens? Your arm should try to lift itself up!
The muscles in your fingers were made to grip, but they don’t have a lot of stamina. To test this, close your hand into a tight fist for one second. Then open and relax it for a second. Continue doing this, counting each time you are able to pen and close your hand. How many times can you open and close before your hand gets tired and you must stop?

What’s going on?

In the first experiment, your arm’s muscles and nerves got used to the pressure being applied by your friend and adjusted to the force. Once your friend stopped applying the pressure your muscles could not adapt immediately. This resulted in your arm lifting up into the air, seemingly of its own accord.

In the second part, your hand was doing a job that it wasn’t really designed to do. You just wore it out!

What do you think are some of your strongest muscles? Would you be surprised to learn that the jaw muscles rank near the top? It’s true: humans can exert the same force when biting down as a shark. This is a force equal to about 200 pounds per square inch!

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Testing Muscle Strength

Sunday November 13, 2011

Some groups of muscles are stronger than others because each group is designed for a different and specific function. It just makes sense that the muscle groups in our legs would need to be stronger than the ones in our toes.

For this experiment, you will use a bathroom scale to test the strength of various muscle groups.

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Here’s what you need

1 bathroom scale
1 pencil
1 partner

Download Student Worksheet & Exercises

Here’s what you do

Put the scale between your knees. Now squeeze it as hard as you can and have your partner record the scale’s reading.
Use the technique to test the muscles in the following list. Place the scale between the body parts and squeeze! Be sure to record the readings for data-keeping purposes.

a. thighs

b. ankles

c. palms

d. elbows

e. elbow and rib cage

What’s going on?

Not all muscles need to be big and powerful. Actually, muscles have various functions and uses that vary by their design. The muscles in our fingers are detail-oriented. They need to be fast and perform relatively small, precise movements like the ones used in writing. The design of a specific muscle group will vary depending upon the muscles’ ultimate use.

Have you even had a muscle cramp? They occur when a muscle is overworked and fatigued. The muscle simply contracts and stays contracted. Not fun!

Exercises

What are the two main types of muscles?
Give an example of a muscle group that’s more specific than your answers above.
Why aren’t the muscles in our fingers big and strong like those in our arms and legs?

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Inside Bones

Sunday November 13, 2011

The skeleton is your body’s internal supporting structure. It holds everything together. In addition to providing support, bones act as shock absorbers when you jump, fall, and run. Bones have big responsibilities and so they must be really strong. They also need to be arranged properly for the best support and shock absorption.

In this experiment, we will look at the internal arrangement of the bones holding together your body.

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Here’s what you need

1 toilet paper tube
50-100 straws
1 roll of tape
1 book

Download Student Worksheet & Exercises

Here’s what you do

First you will explore different bone structures. Start by taking 20 skinny straws and arrange them randomly in your hand so that they are pointing in different directions.
Lay your arm and hand on a table so that it is braced. Next, have a friend place a heavy book on this column of straws. What happens then it’s exposed to the weight?
Now take 20 more straws and arrange in a circle so that they are all held vertically in your hand.
Repeat step 2 with these more organized straws. Do you notice a difference? The uniformly arranged straws should be stronger than those that were randomly arranged.
The tubes inside your bones are more like the uniform model of straws. They also have a kind of glue that hold them in place inside the bones. Let’s incorporate this idea into your model by lining the inside of the toilet paper tube with tape.
Next, add some straws inside the tube as well. Add a single layer of straws, then another layer on top of it. Finally, fill the middle of the tube with straws, making sure they are tightly packed.
Test your model’s strength by placing a book on top of the tube. What happens when the model is exposed to the book’s weight?
For an extra study opportunity, visit the butcher in your local grocery store and ask for the end of a beef bone. (This is sometimes packaged as a soup bone). Look at the end of the bone. What do you see? It should look like a hard outer shell of bone protecting a softer, spongy portion. Draw a picture of your observations.

What’s going on?

In your experiment, it should have been readily apparent that the more organized and uniform straws were much stronger than the randomly arranged ones. Your own bones have a similar pattern in their soft, spongy part called cancellous bone. This portion of bone has a honeycombed structure which makes the bones very strong, but relatively light. The tiny tubes that make up the honeycomb are called the Haversian system and the actual tissue of the structures is made up of collagen. This allows them to maintain flexibility, but they are still composed of minerals – notably calcium and phosphorus which give them their hardness and strength.

Exercises

Name some of the parts that make up our skeletal system.
What is the smooth, hard, protective layer on the outside of bones called?
What is the inside spongy, porous, honeycombed bone called?
What is the network of tubes inside bones called?

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How Your Brain Feels Pain

Sunday November 13, 2011

Your body is made of organs, like your heart, lungs or stomach. These organs work together to allow you to breathe, eat, move, and do just about everything else you need to do. Organs working together are called organ systems. Although all organ systems are important, and necessary for us to survive, the most important system might be the nervous system, the system that controls all the others. This system not only controls all the systems of your body but also allows you to learn and use language, senses conditions inside and outside your body and prepares you to fight or flee if you are in a dangerous situation.

This is a video about the more advanced concepts about neurons, nerves, and signals:

Imagine you walk into your home one night and it’s pitch black. You quickly flick on a light switch and the room is immediately lit up. You may have never thought about it, but it’s kind of amazing that this happens. Even though it may be a long distance from the light switch to the actual light, the light comes on.

Fortunately, messages in your nervous system also travel at the speed of electricity. The nervous system is made of bundles of nerve cells called nerves. Nerve cells called neurons send messages, called nerve impulses, throughout the body. Since these messages are electrical impulses, they travel very quickly. Neurons are also covered with a fatty covering called myelin which insulates the neuron, like the plastic on the outside of a wire, allowing the nerve impulse to travel even faster.

Look at the shape of the neuron. These cells are the perfect shape for their job of sending messages all over the body. The small extensions on the end of the cell are called dendrites and get nerve impulses from other cells. The longer extension at the other end of the cell is called an axon and sends nerve impulses to other cells. The central part of the cell, between the dendrites and axon, is called the cell body. This part of the cell contains the nucleus and all the organelles, which are small structures inside the cell. The place where the axon of a nerve cell meets the dendrites of another nerve cell or another type of cell is called a synapse.

Neurons can be classified, or put into groups, based on their job in the body. Sensory neurons carry messages from the organs to the brain and spinal cord. Motor neurons carry messages from the brain and spinal cord to organs, glands, and muscles.

Have you ever wondered how cells communicate? Here’s a video for advanced, curious students:

As you can see, the nervous system does many things and has many parts. Consider the chart below, which lists the divisions of the system. Each part of the system plays a unique and important role in allowing the other body systems to function.

Nerve Tester

Sunday November 13, 2011

Our sense of touch provides us with information that helps us to process and explore our world. Nerves play an important part in the sense of touch by being the wires that carry signals from the skin to the brain. But the body has a plan in place so that our brains don’t get overwhelmed with too much information. This plan is a lot like a blueprint for wiring a house. Just like a house has light switches and electrical outlets in strategic locations, our bodies have touch receptors of various numbers based on their location. In this lab, we will explore an arm to determine where the highest concentrations of nerves are in that limb.

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Here’s what you need

- 1 large paper clip
- 1 metric ruler
- 1 partner

Download Student Worksheet & Exercises

Here’s what you do

Unfold a paperclip so that it has two open ends. The ends should be about a centimeter apart.
Have your partner uncover their arm up to the shoulder. They should place this arm on the table, palm up, but it is also important that they face away from you. They shouldn’t be able to see the test.
GENTLY touch one or both of the open paperclip ends to your partner’s fingertip. Ask your partner to determine how many points you used to touch them (one or two). Then record their response as (Y) for a correct answer or (N) for incorrect.
Continue testing based on the numbered points in the diagram. Randomly vary the points used to touch your subject’s skin, recording their Y (correct) or N (incorrect) response for each individual area.
Repeat steps 3 and 4, with the paperclip ends separated at a distance of 3 cm, 5 cm, and 10 cm.
Your turn! Switch places and have your partner test you and record your responses.
Finally, use the diagram and your data to design a map of nerve concentrations in the arm and hand. What are some of the advantages of this nerve placement?

What’s going on?

Endings are nerves are located so that we can use them to collect data. The highest concentrations of nerves are in our hands, feet and mouths. We use our hands to gather a lot of data, our feet for moving around, and our mouths for speaking. Luckily, the areas of our bodies that are more likely to be bumped and the ones we use to help protect ourselves have fewer nerve endings. Areas of particularly low concentration include our backs, rear ends, and arms.

Our tongues have the highest nerve concentration of all. In fact, nerve mapping researchers have learned that over half of our brain’s sensory nerves are connected to our tongues. It makes sense when you realize that we taste, talk, and feel with this relatively small organ. It really needs to connect to so many places in the brain!

Exercises

Where is the highest concentration of nerve endings in the body?
What are nerve ends used for?
Where do you think the least amount of nerve ends should be in the body?

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What are Bones?

Sunday November 13, 2011

Bones are made up of several parts; bone marrow (red and yellow), spongy bone, compact bone, and the periosteum. Bone marrow makes blood cells. Red blood cells are made in the red marrow, while white blood cells are made in the yellow marrow. When babies are born they only have red marrow. Spongy bone is a light, spongy type of bone found inside bones. Compact bone, on the other hand, is hard and makes up the outer layer of bones. The compact bone layer is covered by a thin white membrane called the periosteum.

Bones begin growing very early, and stop growing between the ages of 18-25. At about eight weeks of development, we form a skeleton of cartilage and other connective tissues. As we grow up, the cartilage becomes bone. Normally, we have all of our bones by our early twenties. We still keep some of the cartilage in areas like our nose and ears.

Joints are essential in how we move. Bones work as levers and the joints work as the fulcrums—making our movement easier. Some joints are fixed; for example, many in the skull. Some allow only little movement; for example, the vertebrae which make up the backbone. Lastly, there are movable joints; for example, our knees and elbows. These make up the three classes of joints: fixed joints, partly movable joints, and movable joints.

The keys to keeping the skeletal system healthy are: eating well, getting exercise, and taking care of injuries to the skeletal system.

Eating a good balanced diet is very important for overall health, but making sure to get specific nutrients help ensure a healthy skeletal system throughout your life! Those nutrients are: calcium and vitamin D. 1300mg of Calcium is recommended (one cup of milk has about 300mg of Calcium) and 200IU of vitamin D (31/2 ounces of cooked salmon is about 360IU of vitamin D). Calcium can be found in dairy products as well as broccoli and cabbage. Your skin makes vitamin D when exposed to sunlight. Additionally, fish is rich in vitamin D.

It’s important to get out an exercise to maintain a healthy skeletal system. When we exercise we put stress on our bones and stimulate them to stay strong. Exercising also keeps the muscles which work with the bones strong. Just remember to stretch and wear all the appropriate safety gear.

Lastly, if an injury occurs—a bone breaks or a ligament tears, for example—it’s important to see a medical professional as soon as possible. Otherwise, the skeletal system may not heal properly!

Tendon Reflex

Saturday November 12, 2011

Involuntary responses are ones that you can’t control, but they are usually in place to help with survival. One good example is when you touch something hot. Your hand does not take the time to send a message to your brain and then have the brain tell your hand to pull away. By then, your hand might be seriously hurt! Instead, your body immediately removes your hand in order to protect it from further harm.

Today you will test an involuntary reflex by using the tendon reflex test. A thick, rubbery band called the patellar tendon holds your knee cap in place. Having one leg on top of the other not only stretches the tendon, but it also makes it possible to see a reaction. You can test the reflex by giving your tendon a tap and watching what happens.

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Here’s what you need

1 knee
1 partner

Download Student Worksheet & Exercises

Here’s what you do

Sit with your legs crossed at the knee on the edge of your seat. Reach forward and see if you can feel the patellar tendon. It is right below your knee cap.
Ask your partner to gently tap the tendon with the outside edge of their hand. This will look like a careful little karate chop. If your partner gets the right spot it will be obvious. You will notice your leg kick out a little in a reflex reaction.
Your partner can try other spots on the tendon if reaction isn’t achieved at first. If it hurts, stop right away! It’s possible that you might not have a tendon response reflex. Not everyone does and that is perfectly normal.

What’s going on?

There are three main parts that make up your peripheral nervous system. They are the autonomic nerves, which control reflexes like the one we have studies here. Autonomic nerves also send information to your organs, blood, and other parts of the body. The second part of your peripheral nervous system is made up of the nerves that deal with the five senses. The last part is your motor nerves. They help you to move the muscles in your body and are responsible for voluntary reactions.

The tendon reflex is in place because the knee is such a sensitive and vulnerable part of the body. When the tendon is stretched out and bumped, your body tries to move the leg and knee out of harm’s way so that it won’t get hurt. As you could probably tell, it’s an involuntary response that neutralizes any conscious, voluntary control that your brain has over the leg through the motor nerves.

Exercises

What are the main parts of the nervous system?
What are the two parts of the peripheral nervous system and what are their functions?
Which part of the nervous system controls involuntary reflexes?

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Positive and Negative Feedback Loops

Saturday November 12, 2011

Our cells are happiest when they are in their normal or “home” state. This is a state in which the temperature, the concentrations of molecules, and molecules being produced are all at the levels at which they normally function. This “normal” or “home” state is called homeostasis.

Our cells—and the tissues and organs they constitute—work hard to maintain homeostasis. We can see this in action. When it is cold out and we shiver, that’s our body trying to get the temperature up to normal levels. When it’s hot out and we sweat, that’s our body trying to get the temperature down to normal levels. We see our body trying to maintain homeostasis when we feel hungry, or thirsty. Homeostasis is an important characteristic of living things. If you were in the desert, your body would be working hard to maintain homeostasis—despite the high temperature and the lack of water.

There are many different types of cells in the body, but all of them work to maintain homeostasis. For example, there are specific muscle cells for muscles, specific heart cells for the heart, specific pancreas cells for the pancreas, and skin cell cells making up the skin. The different cell types differ in how they function. They all work together to make sure the body functions normally.

A tissue is composed of specific cells performing the same function. An organ is made up of two or more types of tissues working together. Organs which work together form organ systems. Organ systems work together to maintain homeostasis.

So, how many types of tissues are there? There are four main types of tissue. Tissues are groups of cells which together form specific functions. These types are: epithelial tissue, nervous tissue, muscle tissue, and connective tissue. Epithelial tissue is found in tightly packed surface layers; such as the skin, as well as the lining of the digestive system and the lining of the mouth and nose. Nervous tissue is responsible for relaying information. All together the nervous tissues form the nervous system. The nervous system includes the sensory nerves in the body, nerves in the spinal cord, and the brain.

There are three types of muscle tissue; smooth muscle, skeletal muscle, and cardiac muscle. All three cell types have filaments which change the size. Bone, cartilage, and tendon tissues are examples of connective tissue. Connective tissue connects one part of the body to another and is involved in structural support.

The low blood temperature sends a message to the brain which then sends a message to the adrenal gland, which increases the blood temperature by raising the metabolism. The raised blood temperature then signals to the brain that it’s time to stop sending the message to the adrenal gland. A key way organ systems maintain homeostasis is via a negative feedback loop.

A negative feedback loop simply means that the result is a signal to stop. For example, if you haven’t eaten for a while your body will sense that your blood sugar is low. The low blood sugar acts as a signal for the body to start releasing sugar into your blood. However, once the blood sugar levels are back to normal—homeostasis has been reestablished—that normalcy acts as a signal for the body to stop releasing sugar into your blood.

Many problems can occur if these negative feedback loops do not function properly. For example, diabetes is a disease which results from the blood sugar negative feedback loop functioning abnormally.

Detecting Plaque

Thursday November 10, 2011

The buildup of things like food and bacteria where your gums and teeth meet, and also between your teeth, is called plaque. Where plaque lives is also where the bacteria turns the sugar in your mouth into harmful acids that attack your teeth’s enamel and can lead to gum disease. Regular brushing is a great way to remove plaque and keep your mouth healthy.

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Here’s what you need

1 4-pack of red disclosing tablets
1 clear plastic cup
1 mirror
1 red crayon
water

Download Student Worksheet & Exercises

Here’s what you do

Disclosing tablets are designed to identify plaque by turning it red. Remove a pill from the packaging and put it in your mouth. Chew it up thoroughly but don’t swallow it. Be very careful not to get any of the dye on clothing or anything else that might stain. The color is very difficult to remove!
Take the cup full of water and rinse out your mouth very well. Spit the water out into the sink. Check your mouth in the mirror. All of that red is plaque! Draw a picture of your mouth and use the red crayon to note where the plaque is attacking your teeth and gums.
You should have a total of 4 pills in the package. You can test other members of your family, or if you would prefer, test yourself over a period of a few days after you have had a chance to observe and identify where you should be doing a better job of tooth-brushing.

What’s going on?

When you chew the tablets they start to dissolve and mix with your saliva. This makes a water soluble dye that affixes to the bacteria and other particles in your mouth. The dye is absorbed by the bacteria, so it holds onto it even after your mouth is rinsed. This enables you to identify the unbrushed areas in your mouth.

Have you ever counted your teeth? They started to appear when you were a baby – about 6 months old or so. Kids have 20 deciduous, or baby teeth. These will fall out and the adult teeth grow in to replace them. Adults usually have 32 total teeth.

Exercises

Why does this experiment work at detecting plaque?
How can dentists and moms use this to make sure you’re doing a good job brushing?
What is plaque, and why is it bad for you?

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Consuming Oxygen

Tuesday October 18, 2011

This experiment not only explains how your body uses oxygen, but it is also an experiment in air pressure circles – bonus! You will be putting a dime in a tart pan that has a bit of water in it. Then you will put a lit candle next to the dime and put a glass over the candle with the glass’s edge on the dime. Once all of the air inside the glass is used up by the candle, the dime will be easy to pick up without even getting your fingers wet! Ready to give it a try?

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Here’s what you need

- 1 aluminum tart pan
- 1 votive candle
- 1 box of matches
- 1 clear drinking glass, 12 or 16 oz.
- 1 dime
- water
- 1 pair of goggles
- Adult supervision!

Download Student Worksheet & Exercises

Here’s what you do

Pour about ¼ inch of water in the pan and place the dime right in the middle.
Position the candle next to the dime and ask an adult to light it for you
Put the drinking glass over the candle with its edge resting on the dime. Watch closely to observe what happens.
Once the water is inside the glass, you can carefully remove the dime from under its edge. If done properly, the water will stay in the glass.

What’s going on?

When you put the glass over the candle, you created a closed system. The candle only had the gas trapped inside the air beneath the glass to burn. As the candle burned, the gases in the glass burned as well. They were transformed from a state of gas to a very compact solid state that stuck to the wick of the candle (this is why the wick gets black when a candle burns).

An important thing to note is that as the air was removed, the pressure inside the glass was reduces. Lower air pressure inside your closed system created an imbalance with the regular air pressure on the outside of the glass. Since there was more pressure on the outside, the water was pushed inside the glass. The dime helped to make a gateway for the water to be more easily pushed into the glass.

This lab serves to illustrate that oxygen is consumable. It’s the same thing that happens inside your body, but at a much slower rate that what you witnessed with the candle. Your lungs contain about 1,490 miles (2,400 km) of air passages to help absorb oxygen. If they could be spread out flat, an average set of lungs have a surface area of approximately 650 square feet. The sheer size of this system gives you the chance to absorb all the oxygen that your body needs.

Exercises

What do we mean when we say that oxygen is consumable?
What is the difference between an open and a closed system?
Where is the higher pressure in this experiment?
Why does water rise inside the glass?

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How Lungs Work

Sunday October 16, 2011

Take a deep breath in, and slowly let it out. As you do, think about the breaths you take without thinking about it. The truth is, you probably only think about breathing when you are coughing and having a hard time breathing. Even though breathing is not something we think about regularly, it is absolutely required for the survival of the cells in your body. As you breathe, oxygen flows into the body and carbon dioxide flows out. This very important exchange of gases is the main function of your body’s respiratory system.

Sometimes, people will say “breathing” and “respiration” as though they were the same thing, but they are actually very different. Breathing is the process where air enters the body, goes into the lungs, and exchanges its oxygen for carbon dioxide. This is part of respiration, and is known as external respiration, but it only half of full respiration. Respiration also includes internal respiration, where the blood, full of oxygen, goes to the parts of the body that need it. This process can be learned about in a discussion of the circulatory system, another body system.

Measuring the Heart’s Health

Sunday October 16, 2011

The heart is the most important organ in the cardiovascular system. You may heard your heart beat when you were at the doctor’s office, but you may never have thought about what the heart was actually made of. The heart is made of four sections, or chambers. The two chambers at the top of the heart are called the left atrium and right atrium. The two chambers at the bottom of the heart are called the left ventricle and right ventricle.

The job of the atria (that’s the plural of atrium) is to get blood from the other parts of the body. The job of the ventricles is to pump the blood from the heart to other parts of the body. We’ll worry about exactly where the atria are getting the blood from and where the ventricles are sending it to a little later. For now, just make sure you understand that atria get blood in and ventricles pump blood out.

Along with the heart, another important part of the cardiovascular system are blood vessels. There are three main types of blood vessels; arteries, veins, and capillaries. Arteries are blood vessels that carry blood away from the heart. Arteries have thick walls. They need these thick walls because there is a lot of pressure on the blood in arteries. Every time the heart contracts, it creates a force on the walls of the arteries. This force creates pressure. You’ve probably heard of blood pressure, and had your blood pressure taken during a check-up.

Blood pressure is a measure of the pressure on the walls of the arteries caused by your beating heart.
The next types of blood vessels are veins. In many ways, veins are the opposite of arteries. While arteries move blood away from the heart, veins bring blood back to the heart. While arteries have thick walls to handle blood under high pressure, the walls of veins are much thinner, because the blood they carry is under a much smaller amount of pressure. Veins contain valves, which stop the blood they are carrying from moving backwards.

The last types of blood vessels are capillaries. Capillaries connect veins and arteries, and they are tiny. Their walls are only one cell thick, and they are so narrow, blood cells have to go through them single file. In spite of their small size, however, capillaries are the place where one of the most important things in our body happens. Networks of capillaries, called capillary beds, are the places where blood gives off oxygen to the parts of the body, and collects waste products like carbon dioxide. One of the major purposes of the cardiovascular system, oxygen transfer, is happening in these tiny vessels. The more active an organ is, the more capillaries it will need to get oxygen and other nutrients from the blood.

Seeing Your Pulse

Saturday October 15, 2011

Your blood travels through your body very quickly. You probably already know that you can place your finger on certain points – like the radial artery in your wrist – and count the beats of your heart as it pumps blood throughout your body.

In this experiment, we will explore other ways to amplify your blood’s movement so that you can actually see a visual representation of it.

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Here’s what you need

1 lump of modeling clay or plastic putty
1 stopwatch
1 coffee stirrer straw
1 partner

Here’s what you do

Your radial artery in the wrist carries your blood from your heart down to your hand. Use your index and middle fingers to find your pulse in the radial artery on the inside of your left wrist.
Put a small, flat circle of clay on the spot where you found your radial artery’s pulse.
Push one end of the straw carefully into the clay or putty so that it’s standing up, perpendicular to your arm.
Using the stopwatch, record how many beats you see per minute by observing how many times the straw bounces.

What’s going on?

Your blood is pushed out of a chamber by the muscles of your heart and into your arteries, creating a force which is measurable. This is called your blood pressure. Systolic pressure is the resistance to outward blood flow through the arteries. The diastolic pressure is a measure of the blood flowing back to the heart to be oxygenated. Average blood pressure would be recorded as 120/80. Healthy blood pressure is important, since high blood pressure is a risk factor for many illnesses such as heart disease and stroke.

A few more random blood facts for you: there are 4 main types and they are A, B, AB and O. Oxygen binds to hemoglobin in your red blood cells, making an iron-rich compound. This makes the bright red color.

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How to Avoid the Dentist

Saturday October 15, 2011

Digestion involves the breakdown of what we consume into nutrients. The first step is mechanical digestion—chewing. After we mechanically break down the food with our teeth, we begin chemical digestion.

Teeth are small structures found in the mouths of vertebrates. They are calcified, meaning that they contain the element calcium, and are very distinctive based on the type of animal they are found in. Carnivores, or animals that eat meat, have sharp, pointy teeth for ripping and tearing prey. Plant-eating animals, known as herbivores, have larger flat teeth which they use to grind up the tough plant material they eat. Other animals, referred to as omnivores or generalists, eat both plant and animal material. As you might expect, these animals have both types of teeth. Humans fall into this category.

Humans and all other mammals are diphyodont, meaning we will have two sets of teeth in our lifetimes. Not all animals are this way. In fact, rodents and sharks both will continue to grow set after set of new teeth as they gnaw or bite their food. Other animals only have one set of teeth throughout their entire life.

In humans, the front teeth are called incisors. Next to the incisors are the sharp canines. To see how these two types of teeth are used, try a mini-experiment. Take a bite out of a banana and then take a bite of a carrot. Chew them as you would normally, and pay careful attention to what tooth is being used to chew. You’ll notice that for the softer banana, the incisors take the first bites. With the harder carrot, the canines do this job. In both cases, the chewing is done by the pre-molars, which are the teeth next to the canines, and the molars, the large, flat teeth closest to the back of your mouth.

Taking care of your teeth is very important. Brushing your teeth after every meal and flossing every day can go a long way in making sure your teeth stay healthy. If you don’t brush and floss, bacteria can build up over time, leading tartar and plaque on your teeth. If this continues, a small hole, or cavity, can form. Dentists can fill cavities, but this is generally something to be avoided if possible. Your gums can also become infected with bacteria if they are not cleaned. Bleeding gums can be one sign of gum disease. Serious dental procedures, such as extraction (the removal of a tooth) or a root canal are sometimes needed when dental care has been ignored for too long. The best thing to do is to avoid the problem to begin with by brushing, flossing, and visiting a dentist regularly.

What Happens to Food after You Put it in Your Mouth?

Saturday October 15, 2011

What is happening when we feel hungry? Or when we feel thirsty?

What we are feeling are hormones signaling our brain that we need food or water.

Hormones play a large role in our digestion process. They help maintain homeostasis by stimulating appetite, thirst, as well as many, many other bodily functions.

Digestion is the process of food (and drink) being broken down and absorbed. The mouth begins the digestion by breaking down food mechanically and chemically. Protein is digested in the stomach. The small intestine finishes the chemical digestion and absorption of food. The large intestine absorbs excess water from the waste and finally passes it through the anus.

What happens to those meals when they enter our mouths? There are the main things that happen:

Digestion: Digestion involves the breakdown of what we consume into nutrients. The first step is mechanical digestion—chewing. After we mechanically break down the food with our teeth, we begin chemical digestion. Chemical digestion breaks down what we eat and drink chemically. Chemical digestion is mostly accomplished by proteins called enzymes.
Absorption: After we’ve broken down the nutrients we need, we absorb them into our body. This step is called absorption.
Elimination: Lastly, we excrete solid and liquid waste.

Digestion begins in the mouth. In the mouth, the teeth digest food mechanically, and the saliva digests starches chemically. Enzymes are catalysts that make chemical reactions go faster. They are found at every important step of digestion. Amylase is found in our saliva, and it helps breaks down bread-like things (starches) into smaller sugar molecules. Pepsin helps us digest protein in our stomachs. Pancreatic lipase breaks down fats.

After the mouth, the food travels to the stomach through a narrow tube called the esophagus. The esophagus moves the ball of chewed and partially digested food into the stomach. Food is moved through the tube via muscle contractions. The muscle contractions start in the esophagus and end in the anus, moving in a wave called peristalsis. Peristalsis is the name of the movement of the muscle contractions moving the food through the tube.

Once in the stomach, the food is further chemically digested. The protein is digested with the enzyme pepsin. Pepsin, along with other chemicals such as hydrochloric acid (HCl) chemically digest the food. Water, salts, and simple sugars are absorbed through the walls of the stomach. The rest of the nutrients are absorbed after exiting the stomach.

The small intestine, about 7 ft long, has three parts. The large intestine takes the liquid waste from the small intestine, absorbs the excess water, and excretes the solid was through the anus. The large intestine is home to trillions of helpful bacteria. Although we often think of bacteria as harmful, most bacteria is helpful. The bacteria in our small intestines helps us digest food, and we provide the bacteria a place to live. Among other functions, the bacteria in our large intestines produce vitamins B12 and K, as well as break down poisons.

The liver is essential to digestion, and life. The liver detoxifies the blood, maintains the glucose balance, synthesizes proteins, and produces many chemicals needed for digestion.

Getting the right nutrients and getting fiber in your diet is extremely important. The nutrients keep your system running well, while fiber helps to move waste through your digestive system. If you do not get enough fiber you may become constipated; unable to pass waste.

Maintaining a healthy digestive system means a.) maintaining a healthy diet, and b.) taking care of any illnesses, allergies, or intolerances which arise.

What Do I Eat?

Saturday October 15, 2011

Eating and drinking are essential parts of our life. Part of maintaining a healthy lifestyle is making sure to eat and drink the right quantities of the six essential nutrients. Those nutrients are: protein, carbohydrates, lipids, vitamins, minerals, and water.

Does it mean to eat all vegetables? Does it mean to eat only meat? No. A healthy diet is a balanced diet. This is what MyPlate demonstrates. A balanced diet means getting the right amounts of nutrients. MyPlate guidelines are recommendations from the United States Department of Agriculture (USDA). Since 1958 the USDA has recommended a balanced diet in the form of the food pyramid. However, the pyramid proved to be too complicated for most Americans to efficiently use to create diets. In response, the USDA simplified its recommendations in 2011 into the MyPlate format.

We already know what a diet is—the sum of food and drink consumed. Now, what does it mean to have a healthy diet?

The specific advice of the USDA is:

Balance calorie intake.
Enjoy your food, but eat less.
Avoid oversized portions.
Eat certain foods.
Make half your plate fruit and vegetables.
Make at least half your grains whole grains.
Switch to fat-free or low fat (1%) milk.
Eat certain foods in moderation.
Compare sodium in foods like sodium, bread, and frozen meals—and choose the foods with lower numbers.
Drink water instead of sugary drinks.

What’s THAT called?

Friday October 14, 2011

If you’re like me, you like to know about the cool instruments doctors use when they poke and prod you in the standard office visit. I was always curious about what optometrists use during their eye exams. I found an instructional video that teaches optometrists about their tool for examining the fundus here:

Today, some people with vision problems choose to have surgery called LASIK. In this surgery, a laser changes the shape of the cornea correcting the vision problem. As a result, the person usually no longer needs to wear glasses or contacts. However, some problems are not correctable, even with LASIK.

Here’s a video on what it’s like to be blind:

If the vision problems can’t be corrected (as with blind, or no vision), how do people read? The Braille system was developed many years ago. Here’s a video that shows you how it works:

Eye Problems

Friday October 14, 2011

Do you or someone you know where glasses or contact lenses. Glasses and contacts are used to correct vision problems. The two most common eye problems are myopia and hyperopia, and each is fixed a different way.

Myopia is sometimes called nearsightedness. About one third of people have this problem. Myopia happens when the eye is too long. With eye too long, images seen are focused a little bit in front of the retina, instead of on the retina as they would be in a normal eye. People with myopia can see nearby objects clearly. Objects that are far away, however, look blurry. This can be corrected with a concave lens on glasses or contacts. “Concave” means that the lens curves inward, like the inside of a bowl. The concave lens helps focus light on the retina instead of in front of it, correcting the problem.

Hyperopia, which is also called farsightedness, affects about one fourth of people, is pretty much the opposite of myopia. In this disorder, the eye is too short, so images become focused behind the retina. As a result, people with hyperopia can see things clearly when they are far away, but not when they are close up. To correct hyperopia, a convex lens, which is a lens that curves out, like the outside of a bowl, is used in glasses or contacts.

Here’s a video that shows some of the latest technology in eye exams and what optometrists diseases can detect early on:

Some people suffer from both myopia and hyperopia. How can this be? It doesn’t seem possible that the eye could be too long and too short. The answer lies in the lens of your eye. You can think of the lens like a trampoline. As you jump up and down on the trampoline, it moves closer or further from the ground. The lens does a similar thing when you look at things closer together or further away. This makes the overall shape of the eye change slightly. As your trampoline gets older, the springs may begin to wear down, and it may become harder for the trampoline to move. The same thing happens with the lens in your eyes. As a result, many older people develop hyperopia. If these people already had myopia, they will need a lens that has both a concave and convex part. Bifocals are glasses that have these two parts.

Donating Blood

Friday October 14, 2011

If you’ve ever had a blood test, you may have wondered, perhaps as that needle was getting closer and closer, what exactly is the point of this? As it turns out, quite a lot. The standard blood test measures many things. There are also specific blood tests a doctor might order based on a person’s health history or a particular medication he or she is taking. A common blood test is the CBC, which stands for complete blood count. In this test, doctors can obtain counts of red blood cells (RBC) and white blood cells (WBC).

Healthy blood has 4.2 – 6.9 million RBC’s per cubic millimeter of blood and 43,000 108,000 WBC’s per cubic millimeter. That’s a lot of cells!

If a person has anemia, part of the CBC called the mean corpuscle volume (MCV) can help determine the cause. A CBC can also determine the amount of platelets in the blood, a very important number since platelets are needed for blood clotting. A range of 150,000 – 350,000 platelets per milliliter of blood is considered normal. Blood tests also commonly test for cholesterol levels. Cholesterol can clog the blood vessels, making it harder for blood to get around the body. This can lead to heart disease and heart attack. Healthy people generally have less than 225 milligrams of cholesterol per deciliter of blood, although the acceptable amount can increase as people age.

It is important to realize that there are some healthy people who will have blood tests results outside the “normal” range, and some people who are not healthy at all in spite of being within normal limits. This is why blood tests should be interpreted by a doctor or other medical professional. The thing to remember, however, is that blood tests are checking for important medical conditions. So even if it hurts a little for a moment, the test can do an awful lot of good.

Diseases and Defenses Exercises

Wednesday September 7, 2011

Let’s see how much you’ve picked up with these experiments and the reading – answer as best as you can. (No peeking at the answers until you’re done!) Just relax and see what jumps to mind when you read the question. You can also print these out and jot down your answers in your science notebook.

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1.   What is the difference between an infectious and noninfectious disease?
2.   What are four types of pathogens?
3.   How are viruses different than other pathogens?
4.   Can a noninfectious disease be caused by a pathogen?
5.   How do vectors spread disease?
6.   What is the single best way to avoid getting an infectious disease?
7.   How can you avoid coming into contact with vectors when you are out in nature?
8.   What is the body’s first line of defense?
9.   How do body excretions keep you from getting sick?
10. How does mucus stop pathogens?
11.  What role does cilia play in the nose?
12.  What comes out of your body when you cough or clear your throat?
13.  When does your body send out signals for an inflammation?
14.  How are inflammations helpful?
15.  How are fevers helpful?
16.  What types of white blood cells are involved in inflammations?
17.  When would your body produce an immune response?
18.  Where are lymphocytes produced?
19.  What is the function of the thymus gland?
20.  What do killer t-cells do?

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Controlling the Body Exercises

Wednesday September 7, 2011

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How does the nervous system relate to the other organ systems?
What is a synapse?
What organs are in the central nervous system?
What are the three parts of the brain?
If the left side of the cerebrum is injured, will the right or left side of the body most likely be affected? Why?
What do the vertebrae do?
What is the function of myelin?
What is the difference between the somatic and autonomic nervous sytem?
When is the sympathetic nervous system used?
How is a reflex different from a typical message to the brain?
What is the purpose of cones in the eyes?
What is the path of light coming into the cornea?
What happens to images if a person has myopia?
What two things are ears responsible for?
If the hairs in the ears semicircular canals move, what message is sent to the brain?
What are some parts of the body that have many touch receptors?
Where are taste buds found?
What causes Reye’s Syndrome?
What occurs during a seizure?
What are some things you can do to “exercise” your brain?

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Respiratory & Excretory Systems Exercises

Wednesday September 7, 2011

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What is the job of the respiratory system?
What happens to air in the nasal cavity?
What does the diaphragm do when you inhale?
Why is it important for the epiglottis to cover the trachea when you are eating?
What happens in the alveoli?
When pressure is different, in what direction do fluids flow?
How does your body use differences in pressure when you exhale?
What is the difference between breathing and respiration?
What is internal respiration?
What disease results from an inflammation on the bronchi?
What types of things can cause an asthma attack?
What types of things cause pneumonia?
Why are the lungs part of both the respiratory and excretory system?
Besides the excretory system, what system are the kidneys a part of?
What do the kidneys do?
What is urine?
After traveling down the ureters, where does urine go?
How do kidney stones develop?
What is the purpose of a kidney dialysis machine?
What are the most common types of UTI?

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Cardiovascular System Exercises

Wednesday September 7, 2011

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1. What is the overall purpose of the cardiovascular system?
2. How could body temperature be affected if someone has poor circulation?
3. What are the four parts of blood?
4. Sickle-cell anemia is a disease in which RBC’s cannot carry hemoglobin properly. What could happen to a person who has sickle-cell anemia?
5. What protein give’s RBC’s their red color?
6. What would happen to a person with too few WBC’s?
7. Hemophilia is a disease in which platelets do not work properly. What could happen to someone who has hemophilia?
8. Why do arteries have thick walls?
9. Why do veins have valves?
10. Name the four chambers of the heart.
11. Where does the pulmonary artery start? Where does it lead?
12. What is the difference between oxygen-rich and oxygen poor blood?
13. What happens to blood in the lungs?
14. What is the name of the only vein that carries oxygen poor blood?
15. Which chamber of the heart does blood enter after leaving the pulmonary vein?
16. In which blood vessel does oxygen transfer happen?
17. Where do the superior and inferior vena cava lead?
18. Which organ gets blood from the coronary artery?
19. What is the difference between systolic and diastolic blood pressure?
20. How can hypertension be treated?
21. When can atherosclerosis cause a heart attack?
22. What happens if blood vessels leading to the brain are blocked?
23. What are three benefits of not smoking related to the cardiovascular system

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Digestive System Exercises

Wednesday September 7, 2011

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1. What is a diet?
2. Why does our body need nutrients?
3. What are the six essential nutrients? Describe them in your own words.
4. What model of a proper diet do we currently use; MyPlate or MyPyramid?
5. What are the three general pieces of advice the USDA gives in regards to maintaining a healthy diet?
6. Does the protein food group, according to the USDA, include only meat?
7. Is 30% lean meat the type of meat you should buy often? Why or why not?
8. What is the difference between “enriched” grains and “non- enriched” grains?
9. Do “enriched” refined grains contain fiber?
10. Who should avoid dairy products?
11. If you eat a healthy, balanced diet, is it necessary to get weekly exercise? If so, how much?
12. What is the difference between mechanical digestion and chemical digestion?
13. What are the two steps after digestion?
14. Name two key enzymes used for digestion.
15. What is peristalsis?
16. Is protein chemically digested in the mouth? If not there, where?
17. What are the three parts of the small intestine? What are their functions?
18. What is the main function of the large intestine?

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Skin, Bones & Muscles Exercises

Wednesday September 7, 2011

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1. What is homeostasis?
2. What is an example of the body maintaining homeostasis?
3. Cells make up tissues, at least how many tissues make up an organ?
4. What are the four main types of tissues?
5. Describe how a negative feedback works and give an example.
6. What is the biggest organ in the body?
7. The skin, hair, and nails make up which system?
8. What are three ways the integumentary system helps maintain homeostasis?
9. What are the two layers of skin? What is the fatty layer underneath the skin called?
10. What role does melanin play in the skin?
11. What causes acne?
12. What three components make up the skeletal system?
13. What are the main functions of bones?
14. What is the difference between red bone marrow and yellow bone marrow?
15. What are the three classes of joints?
16. What are the four types of movable joints?
17. What are two key nutrients bones need?
18. What’s the difference between skeletal muscle, smooth muscle, and cardiac muscle?
19. Muscles work in pairs, what do we call the one that bends the joint? What do we call the one that straightens the joint?
20. What is the difference between stretching exercises, aerobic exercises, and anaerobic exercises?

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Answers to Diseases and Defenses Exercises

Tuesday September 6, 2011

Let’s see how you did! If you didn’t get a few of these, don’t let it stress you out – it just means you need to play with more experiments in this area. We’re all works in progress, and we have our entire lifetime to puzzle together the mysteries of the universe!

Here’s printer-friendly versions of the exercises and answers for you to print out: Simply click here for printable questions and answers.

Answers:
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1. What is the difference between an infectious and noninfectious disease? Infectious disease can be spread, but noninfectious disease cannot

2. What are four types of pathogens? Bacteria, viruses, protozoa, and fungi

3. How are viruses different than other pathogens? They are not alive

4. Can a noninfectious disease be caused by a pathogen? Yes

5. How do vectors spread disease? They bite someone with the pathogen, keep the pathogen with them, then spread that pathogen to the next person they bite

6. What is the single best way to avoid getting an infectious disease? Washing your hands

7. How can you avoid coming into contact with vectors when you are out in nature? Wear long sleeves and long pants

8. What is the body’s first line of defense? The thick outer layer of the skin called the epidermis

9. How do body excretions keep you from getting sick? Many body excretions contain pathogen-killing chemicals

10. How does mucus stop pathogens? Pathogens get stuck in the sticky mucus

11. What role does cilia play in the nose? Cilia sweeps up pathogens and moves them out of the body

12. What comes out of your body when you cough or clear your throat? Mucus and pathogens

13. When does your body send out signals for an inflammation? When pathogens have entered the body through the skin

14. How are inflammations helpful? They bring white blood cells to the site of the infection

15. How are fevers helpful? They raise your body temperature, making it harder for many pathogens to reproduce quickly

16. What types of white blood cells are involved in inflammations? Phagocytes

17. When would your body produce an immune response? When both the first and second lines of defense have failed

18. Where are lymphocytes produced? In red bone marrow

19. What is the function of the thymus gland? To store lymphocytes until they are mature

20. What do killer t-cells do? Attack and destroy specific pathogens

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Answers to Controlling the Body Exercises

Tuesday September 6, 2011

Here’s printer-friendly versions of the exercises and answers for you to print out: Simply click here for printable questions and answers.

Answers:
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1. How does the nervous system relate to the other organ systems? The nervous system controls the other systems

2. What is a synapse? The place where the axon of one neuron meets the dendrite of another

3. What organs are in the central nervous system? The brain and spinal cord

4. What are the three parts of the brain? Cerebrum, cerebellum, and brain stem

5. If the left side of the cerebrum is injured, will the right or left side of the body most likely be affected? Why? The right, because each hemisphere of the cerebrum controls the opposite side of the body

6. What do the vertebrae do? Protect the spinal cord

7. What is the function of myelin? Allow messages to move quickly along nerve cells

8. What is the difference between the somatic and autonomic nervous sytem? The somatic system controls voluntary system, while the autonomic system controls involuntary motion

9. When is the sympathetic nervous system used? In emergencies

10. How is a reflex different from a typical message to the brain? Reflexes bypass the brain, and are controlled by the spinal cord

11. What is the purpose of cones in the eyes? To see in color

12. What is the path of light coming into the cornea? After passing the cornea, the light goes through the pupil, then the lens, and is focused on the retina

13. What happens to images if a person has myopia? The image focuses in front of the retina instead of on it

14. What two things are ears responsible for? Hearing and body position (balance)

15. If the hairs in the ears semicircular canals move, what message is sent to the brain? That the body is moving

16. What are some parts of the body that have many touch receptors? Palms, soles of feet, lips, tongue

17. Where are taste buds found? On the tongue

18. What causes Reye’s Syndrome? Giving aspirin to young children with viral infections

19. What occurs during a seizure? A person becomes unconscious and may have violent jerking motions

20. What are some things you can do to “exercise” your brain? Read, learn, and do activities like crossword puzzles

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Answers to Respiratory & Excretory Systems Exercises

Tuesday September 6, 2011

Here’s printer-friendly versions of the exercises and answers for you to print out: Simply click here for printable questions and answers.

Answers:
[am4show have=’p8;p9;p29;p56;’ guest_error=’Guest error message’ user_error=’User error message’ ]

1. What is the job of the respiratory system? to provide the body with oxygen and remove carbon dioxide

2. What happens to air in the nasal cavity? air is warmed and moistened

3. What does the diaphragm do when you inhale? contracts to make more room in the chest

4. Why is it important for the epiglottis to cover the trachea when you are eating? this prevents food from going down the trachea

5. What happens in the alveoli? oxygen travels from the alveoli to the blood and carbon dioxide travels from the blood to the alveoli

6. When pressure is different, in what direction do fluids flow? from high to low pressure

7. How does your body use differences in pressure when you exhale? the pressure inside the body increases, becoming greater than the pressure outside, causing air to flow out

8. What is the difference between breathing and respiration? breathing is the act of air coming in and out of the body; respiration includes all gas transfer

9. What is internal respiration? the transfer of oxygen from the blood to the various parts of the body

10. What disease results from an inflammation on the bronchi? bronchitis

11. What types of things can cause an asthma attack? change of temperature, physical activity, poor air quality

12. What types of things cause pneumonia? bacteria, viruses, fungi, and parasites

13. Why are the lungs part of both the respiratory and excretory system? they are involved gas exchange as well as removing a waste product (carbon dioxide)

14. Besides the excretory system, what system are the kidneys a part of? urinary

15. What do the kidneys do? filter urine

16. What is urine? a mixture of water and nitrogen-containing compounds, including urea

17. After traveling down the ureters, where does urine go? to the bladder

18. How do kidney stones develop? nitrogen-containing compounds crystallize in the urinary system

19. What is the purpose of a kidney dialysis machine? to act as the kidneys by filtering blood, if the kidneys have shut down

20. What are the most common types of UTI? bladder infections

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Answers to Cardiovascular System Exercises

Tuesday September 6, 2011

Here’s printer-friendly versions of the exercises and answers for you to print out: Simply click here for printable questions and answers.

Answers:
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1. What is the overall purpose of the cardiovascular system? to move blood to the various parts of the body

2. How could body temperature be affected if someone has poor circulation? the body would not be able to heat up or cool down to the ideal temperature

3. What are the four parts of blood? plasma, platelets, RBC’s, WBC’s

4. Sickle-cell anemia is a disease in which RBC’s cannot carry hemoglobin properly. What could happen to a person who has sickle-cell anemia? Oxygen would not get to the organs of the body.

5. What protein give’s RBC’s their red color? hemoglobin

6. What would happen to a person with too few WBC’s? they would have a weak immune system and could more easily get diseases

7. Hemophilia is a disease in which platelets do not work properly. What could happen to someone who has hemophilia? their blood would not clot when they got minor cuts and scrapes

8. Why do arteries have thick walls? because the blood in them is under high pressure

9. Why do veins have valves? to keep the blood from flowing backwards

10. Name the four chambers of the heart. right atrium, left atrium, right ventricle, left ventricle

11. Where does the pulmonary artery start? Where does it lead? it starts at the heart and leads to the lungs

12. What is the difference between oxygen-rich and oxygen poor blood? oxygen-rich blood has oxygen and oxygen-poor blood has very little

13. What happens to blood in the lungs? it gets oxygen

14. What is the name of the only vein that carries oxygen poor blood? pulmonary vein

15. Which chamber of the heart does blood enter after leaving the pulmonary vein? left atrium

16. In which blood vessel does oxygen transfer happen? capillaries

17. Where do the superior and inferior vena cava lead? the right atrium of the heart

18. Which organ gets blood from the coronary artery? heart

19. What is the difference between systolic and diastolic blood pressure? systolic is the highest blood pressure; diastolic is the lowest

20. How can hypertension be treated? improved diet, increased exercise, or medication

21. When can atherosclerosis cause a heart attack? when a coronary artery becomes completely blocked

22. What happens if blood vessels leading to the brain are blocked? a stroke

23. What are three benefits of not smoking related to the cardiovascular system decreased risk of hypertension, coronary heart disease, and stroke

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Answers to Digestive System Exercises

Tuesday September 6, 2011

Here’s printer-friendly versions of the exercises and answers for you to print out: Simply click here for printable questions and answers.

Answers:
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1. What is a diet? The sum of the food and drink consumed considered in terms of its effect on health

2. Why does our body need nutrients? Because it needs energy, it needs to grow/repair itself, and it needs to maintain the systems that maintain homeostasis.

3. What are the six essential nutrients? Describe them in your own words. Protein, carbohydrates, lipids, vitamins, minerals, water.

4. What model of a proper diet do we currently use; MyPlate or MyPyramid? MyPlate.

5. What are the three general pieces of advice the USDA gives in regards to maintaining a healthy diet? Balance calories intake, eat certain [nutrient rich] foods, eat fatty and sugary foods in moderation.

6. Does the protein food group, according to the USDA, include only meat? No it also includes vegetables, fish, eggs, and poultry.

7. Is 30% lean meat the type of meat you should buy often? Why or why not? No, because it has far too much fat. You should look for 94% lean meat.

8. What is the difference between “enriched” grains and “non- enriched” grains? Enriched grains contain vitamins and minerals we need that are lost in the refining process.

9. Do “enriched” refined grains contain fiber? No, fiber is not added back to enriched refined grains.

10. Who should avoid dairy products? People who cannot digest lactose—people who are lactose intolerant.

11. If you eat a healthy, balanced diet, is it necessary to get weekly exercise? If so, how much? Yes, exercise is always necessary. 60 minutes of exercise three days a week is a good level of activity.

12. What is the difference between mechanical digestion and chemical digestion? Mechanical digestion is accomplished with the teeth, which chemical digestion breaks food down into the nutrients via chemicals and enzymes (catalysts).

13. What are the two steps after digestion? Absorption and elimination.

14. Name two key enzymes used for digestion. Amylase, pepsin, or pancreatic lipase.

15. What is peristalsis? Peristalsis is the wave-like movement of the digestive system used to move food from the mouth to anus.

16. Is protein chemically digested in the mouth? If not there, where? No, protein is digested by pepsin in the stomach.

17. What are the three parts of the small intestine? What are their functions? The duodenum, the jejunum, and the ileum. The duodenum is the first part of the small intestine. In the duodenum the food from the stomach is further digested (chemically). Some of the chemicals are secreted from the duodenum itself, others are secreted from the liver and pancreas.The jejunum; Most nutrients are absorbed into the body at this second part of the small intestine. The nutrients are absorbed through tiny blood vessels. The ileum Here nutrients are also absorbed into the blood stream. What is not absorbed in the ileum is passed as waste through the large intestine.

18. What is the main function of the large intestine? Eliminate solid waste from the body.

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Answers to Skin, Bones & Muscles Exercises

Tuesday September 6, 2011

Here’s printer-friendly versions of the exercises and answers for you to print out: Simply click here for printable questions and answers.

Answers:
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1. What is homeostasis? The ability of the body to maintain a stable internal environment in the response to external changes.

2. What is an example of the body maintaining homeostasis? Many examples to choose from. One might be when we sweat to keep our body temperature down, or when we shiver to keep the temperature up. Another example is how we regulate the amount of sugar in our blood. All of the examples should show how the body uses a negative feedback loop to maintain homeostasis. We sweat just until we are cooled down, we shiver until we are warmed up, and we put sugar in our system just until we have enough.

3. Cells make up tissues, at least how many tissues make up an organ? Two or more tissues working together to serve the same function constitute an organ.

4. What are the four main types of tissues? Epithelial tissue, muscular tissue, nervous tissue, and connective tissue.

5. Describe how a negative feedback works and give an example. A mechanism of control in the body in which the result of a bodily function acts as a signal to stop. Plus one example (like the control of blood sugar, or blood temperature).

6. What is the biggest organ in the body? The skin.

7. The skin, hair, and nails make up which system? The integumentary system.

8. What are three ways the integumentary system helps maintain homeostasis? 1.) Helping regulate temperature, 2.) Sending sensory information about the environment outside the body to the brain 3.) Keeping water and germs out of the body 4.) Acts as a barrier to sunlight.

9. What are the two layers of skin? What is the fatty layer underneath the skin called? The two layers are the epidermis and the dermis. The fatty layer beneath is the hypodermis or subcutaneous tissue.

10. What role does melanin play in the skin? It pigments the skin, and helps protect the lower layers from harmful UV rays.

11. What causes acne? Clogging of the oil glands.

12. What three components make up the skeletal system? Bones, ligaments, and cartilage.

13. What are the main functions of bones? Support: Bones give the body its structure—its shape. It holds up the tissue against the pressure of gravity. protection: The bones protect certain tissues. For example, the skull protects the brain, and the ribs protect the heart and lungs. Movement: The bones work in concert with the muscles to give us the ability to move. Making Blood Cells: Certain parts of certain types of bones make blood cells. Storage: Bones store calcium and phosphorus (mostly calcium).

14. What is the difference between red bone marrow and yellow bone marrow? Red bone marrow makes red blood cells while yellow bone marrow makes white blood cells.

15. What are the three classes of joints? Fixed, partly-movable, and movable.

16. What are the four types of movable joints? Ball and socket joints, hinge joints, pivot joints, and gliding joints.

17. What are two key nutrients bones need? Calcium and vitamin D.

18. What’s the difference between skeletal muscle, smooth muscle, and cardiac muscle? Skeletal muscle is attached to our bones and allow us to move. We do not control smooth muscle. Cardiac muscle is only found in the heart.

19. Muscles work in pairs, what do we call the one that bends the joint? What do we call the one that straightens the joint? The muscle that bends the joint is called the flexor, and the one that straightens the joint is called the extensor.

20. What is the difference between stretching exercises, aerobic exercises, and anaerobic exercises? Stretching exercises warm-up our muscles and make them more flexible, anaerobic exercise build our muscles by making them work against resistance, and aerobic exercises increase our endurance.

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Can Bacteria Get Sick?

Monday August 22, 2011

When you hear the word “bacteria” what do you think of? If you’re like most people, you probably think of things that can make you sick. Although some bacteria do make us sick, this is not true for all of them. In fact, as we’ll see a little later, some bacteria are very helpful.

Did you know that bacteria can have a virus? It’s true! But first, you might be wondering: what’s the difference between viruses and bacteria?

Bacteria grows and reproduces on its own, while viruses cannot exist or reproduce without being in a living cell of a plant, animal, or even bacteria. Size-wise, bacteria are enormous.

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The T4 bacteriophage is a virus that looks like a spaceship from an alien planet. It attaches to the surface of the Escherichia coli (E. coli) bacteria using its six legs and injects DNA into the bacteria. The DNA then tells the bacteria to multiply and essentially fill the bacterial cell to bursting. This is how the T4 kills E. coli.

In this video below, you’ll first see large E. coli bacteria floating around, one of which is attacked by a T4 bacteriophage. Notice how the T4 injects the DNA strand into the bacterium. (What’s not shown is how it bursts, but we’ll leave that to your imagination!)

Some bacteria are responsible for diseases in humans and other organisms. Strep throat, tuberculosis, and pneumonia are all the result of bacteria.

Bacteria can also be responsible for food poisoning. Raw eggs and undercooked meats can contain bacteria that can cause digestive problems. One simple step everyone can take to reduce these kinds problems is washing your hands before cooking or eating. Cleaning cooking surfaces and fully cooking food can also help.

In 2007 the United States Food and Drug Administration (FDA) approved using bacteriophages on all food products. Other places you’ll find bacteriophages are in hospitals, uniforms, sutures and surgery surfaces where it’s important to keep surfaces very clean.

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