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The Stomach.

Background

Put your hand on your stomach. Did you place your hand on your navel? Most people do, but that is actually where your intestines are located. Your stomach is much higher than that -- it is located behind the bottom rib on your left side.

Your stomach is just a small part of a long "food tube" that turns the foods you eat and drink into the energy you need to live and work. Food also provides the raw materials necessary for building tissue, fluids, and the other components of your skin, muscles, brain, and other organs. The old adage, "You are what you eat," really is true!

Before your body can use the food you eat, it must be broken down into tiny molecules. Many different kinds of chemicals help in this process. The molecules then pass through the walls of your intestines and are carried by blood cells to every corner of your body. The simple term for this complicated process is digestion.

Digestion Begins

The process of digestion starts in your mouth. Your teeth and tongue crush and mix your food with saliva from your salivary glands. Saliva helps moisten and dissolve certain kinds of foods, but it also contains chemicals which change starch molecules into sugar, nature's simplest form of energy. Your tongue also helps form the food in your mouth into a ball called a bolus (BOH les) when you swallow. ("Bolus" means "ball" in Latin.)

As the food moves to the back of your throat, a special flap of skin called the epiglottis (ep i GLOT is) covers the opening of your airway so that food doesn't "go down the wrong pipe." Food is actively pushed down to the stomach by the muscles that ring the esophagus (i SOF eh gehs), the tube connecting the mouth and stomach. This pushing action, called peristalsis (pair eh STOL sis), is similar in a way to pushing squirts of toothpaste out of a toothpaste tube. The muscles in the esophagus enable you to swallow even if you are standing on your head! A swallow of water takes about 2 seconds to reach your stomach, while a bite of solid food may take 5 to 10 seconds. At the bottom of the esophagus, a ring-shaped "door" called the esophageal sphincter opens to allow the food to enter your stomach. It quickly closes again so that food and stomach acid don't escape up the esophagus and cause the burning pain we call "heartburn."

Into the Stomach

The stomach is a tough, muscular, J-shaped sack. Empty, it holds about 2 cups of liquid, but it can easily stretch to hold 1 to 2 quarts of food. Thanksgiving-sized meals may cause your stomach to stretch to hold twice that amount! Your stomach is lined with millions of tiny glands that produce a digestive liquid called gastric juice (mostly hydrochloric acid). This acid is strong enough to strip the paint off a car! To keep this acid from digesting the stomach itself, special glands make mucus to protect your stomach lining.

Even with this mucus, your stomach needs its lining replaced every 3 days! The acid helps break down tough food as your stomach's muscles grind and squeeze it. Stomach acid also helps kill germs in the foods you eat and protects you from infection. After 3 to 5 hours, this soupy food - now called chyme (kiem) is ready to pass through your pyloric sphincter, the "exit door," and into the first part of the small intestine or duodenum (doo OD en em).

Intestines

The small intestine is very long - from 13 to 24 feet in adults. It is coiled and looped in the center of your abdomen. New digestive juices flow into the duodenum to continue the digestive process. Bile, made in the liver and stored in the gall bladder, helps break up globs of fat and oil in the chyme. Your pancreas adds the hormone, insulin (IN seh len), which regulates the amount of sugar that enters the bloodstream. The pancreas also makes other digestive juices that help break down carbohydrates and digest fats and oils. In people who have the disease diabetes, the pancreas makes too little insulin.

As the digested food passes farther into the small intestine, tiny pouch-like fingers of intestinal lining called villi absorb the nutrients and pass them into the bloodstream. At the end of the small intestine the remaining undigested food passes into the large intestine, also known as the colon. As the waste material flows through this 5 to 6 foot long organ, water and mineral salts are removed and recycled into the body. The dried, compacted waste then passes into the rectum and is expelled out of the body through another muscular sphincter, the anus. The dried waste, called feces, is made up of one-third old food, one-third dead bacteria, and one-third minerals, bile, mucus, and bits of intestinal lining.

Digestive Problems

Since digestion is such a complicated process and requires so many different organs, it is not surprising that there are a number of things that can go wrong. Food poisoning brought on by contaminated food may cause vomiting. When you vomit, the muscles in your abdomen force food out of the stomach and up through the esophagus. Sometimes your stomach makes too much stomach acid or produces it when the stomach is empty. This can cause painful sores called ulcers to develop in the stomach lining. Recently doctors have discovered a bacterium, Helicobacter pylori, that may also cause ulcers. Many people with ulcers can be successfully treated with antibiotics and antacid medicine. The appendix, a small pocket at the entrance of the large intestine, is another site where problems occasionally occur. If the opening of this tiny pouch becomes blocked, the material inside may begin to decay. When this happens, you may develop appendicitis, as the appendix becomes swollen with infection. Usually, doctors will do emergency surgery to remove the appendix before it bursts and spreads the infection into the abdomen.

If you haven't eaten in a while, your stomach may begin to "growl." This is just your stomach muscles churning, getting ready for new food to arrive. They are squeezing the air you swallowed with your last meal. The scientific word for this growling noise is borborygmus (bor ba RIG mas). Sometimes the air escapes up the esophagus, which will produce a burp! Other times, air may move along with your food and make gurgling noises as it travels farther along your digestive tract.

DID YOU KNOW??

Your body makes about 3 gallons of digestive juices every day.

DID YOU KNOW??

A swallow of water takes 2 seconds to reach your stomach. A bite of hamburger takes about 10 seconds.

DID YOU KNOW??

It takes anywhere from 12 to 36 hours for food to pass all the way through your digestive system.

National Science Education Standards

Unifying Concepts and Processes (K-8)

* Systems, order, and organization

* Evidence, models, and explanation

* Constancy, change, and measurement

* Form and function

Standard A: Science as Inquiry (K-8)

* Abilities necessary to do scientific inquiry

* Understanding about scientific inquiry

Standard C: Life Science

(K-4)

* The characteristics of organisms

* Organisms and environments

(5-8)

* Structure and function in living systems

* Regulation and behavior

* Diversity and adaptations of organisms

Standard F: Science in Personal and Social Perspectives

(K-8)

* Personal health

Level Pre-A

Main Concepts: Your stomach helps to break down the food you eat and turn it into energy.

Picture Activity

Ask your students, "What is WHY-FLY looking at? Do you know what that is in the middle of the girl?" It's her stomach. Explain that the food we eat turns into the fuel that helps our bodies to run. How does this happen? Digestion starts in our mouths, where we chew our food. From there, food travels to our stomachs where it is ground up even more. Ask them to put their hands on their stomachs. Now have them look at WHY-FLY's other hand. Are their hands in the same place? The stomach is not below our waists. It is actually behind and just above the bottom rib on the left side. Most people place their hands much too low. Our intestines are behind our navel - where most people think their stomach is located.

Vocabulary

Answers: star, stairs (steps), stamp, stapler. Have them draw lines from the picture of the stomach to the other pictures that start with "st." (They will not draw lines to the lamp, the cat, or the nose.)

Weekly Lab

You need (for each student): a zip-top bag, a sugar cube, a saltine cracker, and 1/4 cup of water. Have each student place a cracker, a sugar cube, and water into a bag and carefully press the top closed. (Be sure the bags are properly sealed before the next step!) Explain that the strong muscles in your stomach grind and mash up the food you eat. Have your students use their hands to squeeze the contents of the bag until they are completely mixed. This soupy food is called chyme and the contents of their bags will be similar to what digested food looks like in our stomachs.

Weekly Problem

Answer: The yellow tray holds 5 glasses. We all need water to digest our food. Our digestive system makes about 3 gallons of digestive juices each day. Children should drink at least 5 8-ounce glasses of water or other liquid each day to stay hydrated. (Adults need 8 8-ounce glasses of fluids.)

Storytelling

Have your students look at the picture and then describe what they think is happening. The children in the picture are remembering other times they felt "butterflies" in their stomachs - on a roller coaster, while waiting in the doctor's office, etc. How do WHY-FLY and the other actors feel? Ask them to tell a story about a time they felt the same way.

Challenge

You need (for each student): a saltine cracker. Give each student a cracker and tell them to just keep it in their mouths, BUT not to chew it. Saliva will quickly flood their mouths and begin to "melt" the crackers. For foods like crackers, there is little need to chew. (Can they think of any others?)

Home Base

Do this activity in class first. Then have your students challenge their families tonight to "put their hands on their stomachs." They can then show their families its true location.

DID YOU KNOW??

Your Body is 2/3 water!

DID YOU KNOW??

A big meal may stay in your stomach for as long as 5 hours.

Level A

Main Concepts: Your stomach helps to digest the food you eat and turn it into energy.

Picture Activity

Ask your students, "What is WHY-FLY looking at? Do you know what that is in the middle of the girl?" It's her stomach. Explain that the food we eat turns into the fuel that helps our bodies to run. How does this happen? Digestion starts in our mouths, where we chew our food. From there, food travels to our stomachs where it is ground up even more. Ask them to put their hands on their stomachs. Now have them look at WHY-FLY's other hand. Are their hands in the same place? The stomach is not below our waists. It is actually behind and just above the bottom rib on the left side. Most people place their hands much too low. Our intestines are behind our navel -- where most people think their stomach is located.

Vocabulary

Answers: star, stairs (steps), stamp, stapler, stove. Have them draw lines from the picture of the stomach to the other pictures that start with "st." (They will not draw lines to the spoon, the saw, or the cat.)

Weekly Lab

You need (for each student): a zip-top bag, a sugar cube, a saltine cracker, and 1/4 cup of water. Have each student place a cracker, a sugar cube, and water into a bag and carefully press the top closed. (Be sure the bags are properly sealed before the next step!) Explain that the strong muscles in your stomach grind and mash up the food you eat. Have your students use their hands to squeeze the contents of the bag until they are completely mixed. This soupy food is called chyme and the contents of their bags will be similar to what digested food looks like in our stomachs.

Weekly Problem

Answers: 3, 4, 1, 2. This activity will show your students the different combinations of 5. We need water to digest food. Our digestive system makes about 3 gallons of digestive juices each day. Children should drink at least 5 8-ounce glasses of water or other liquid each day to stay hydrated. (Adults need 8 8-ounce glasses of fluids.) Have them complete the number sentences.

Writing for Science

Have your students look at the picture and then describe what they think is happening. The children in the picture are remembering other times they felt "butterflies" in their stomachs - on a roller coaster, while waiting in the doctor's office, etc. How do WHY-FLY and the other actors feel? Ask them to write a story about a time they felt the same way.

Challenge

You need (for each student): a saltine cracker. Give each student a cracker and tell them to just keep it in their mouths, BUT not to chew it. Saliva will quickly flood their mouths and begin to "melt" the crackers. For foods like crackers, there is little need to chew. (Can they think of any others?) Ask them if the flavor of the cracker changed. It will taste sweeter, because saliva breaks down starchy food into sugar as part of digestion.

Home Base

Do this activity in class first. Then have your students challenge their families tonight to "put their hands on their stomachs." They can then show their families its true location.

DID YOU KNOW??

Your mouth makes about 1 1/2 quarts of saliva each day

Level B

Main Concepts: Your stomach is just a small part of a long "food tube" that digests food and turns it into energy. Digestion starts in your mouth. Your stomach grinds up the food even more. The food later passes into your blood to be carried to all the different parts of your body.

Vocabulary

Answers: stapler, stairs (steps), stamp, stove. Have your students draw lines from the picture of the stomach to the other pictures that start with "st." (They will not draw lines to the spoon, the saw, the ship, or the sled.)

Weekly Lab

Be sure that your students have properly sealed their zip top bags before kneading them. Explain that the strong muscles in your stomach grind and mash up the food you eat. This soupy food is called chyme. To extend this activity, give each student a saltine cracker. Tell them to hold the crackers in their mouths without chewing. Saliva will quickly flood their mouths and begin to "melt" the crackers. For foods like crackers, there is little need to chew. (Can your students think of others?) Ask your students if the flavor of the crackers changed while they were in their mouths. They will taste sweeter, because saliva breaks down starchy food into sugar as part of digestion.

Weekly Problem

Answers: 1) 15 glasses 2) 35 glasses 3) depending on the month -- 150 glasses in November, 155 glasses in December.

Writing for Science

Have your students study the picture and then describe what they think is happening. The children in the picture are remembering other times they felt "butterflies" in their stomachs - on a roller coaster, while waiting in the doctor's office, etc. How do WHY-FLY and the other actors feel? Answers may range from excited to nervous to terrified. Ask them to write and illustrate a story about a time they felt the same way.

Challenge

The total length of the digestive tract is 5 to 6 times one's height. A child's "food tube" is between 20 to 24 feet, and an adult's is between 26 and 30 feet. Use yarn or string to measure a length of yarn 6 times the height of each child. See the box on the next page for the length of each section of the digestive tract.

Home Base

"You are what you eat" is actually true. Explain that they will be keeping a daily list at home to see how well they are meeting the guidelines for good nutrition. Food contains nutrients. Some provide the raw materials for building body parts. Others supply energy so the body can work. Ask your students to list everything they have eaten in one day. Then have them study the food pyramid. How many of the foods they ate are from each food group?
mouth 4 inches
esophagus 10 inches
stomach 4 inches
small intestine 18 inches
large intestine 5 inches
colon 4 inches
rectum 5 inches
anus the end


Level C

Main Concepts: Your stomach is just a small part of a long "food tube" that digests food and turns it into energy. Digestion starts in your mouth. Your strong stomach muscles grind the food you eat. Then, food passes through your intestines and into your blood to be carried to all the parts of your body.

Vocabulary

ACROSS: 2) energy 4) digestion 6) stomach 7) teeth

DOWN: 1) food 3) esophagus 5) mouth.

Weekly Lab

Adult supervision required. (Note: This lab uses tincture of iodine to test for the presence of starch in food. Iodine is a skin antiseptic for external use only. It is poisonous and can stain skin and clothing if not used carefully. Remind your students to use care when handling iodine solutions. Small bottles of iodine antiseptic can be purchased at drugstores. Do not purchase de-colorized iodine. Betadine[R] solution will also work.) In this lab, your students will see how saliva reduces the amount of starch in a saltine cracker using iodine as a chemical indicator. If you add iodine to foods that contain starch (bread, pasta, potatoes, rice, or crackers, for instance), the iodine will turn from its orangy-brown color to a dark blue-black. Have your students crush a cracker in a cup (a zip-top bag will work well, too) and add 2 Tbls. water. When 10 drops of iodine are added, the mixture will appear dark blue to black. Have your students chew a second saltine long enough to mix it thoroughly with saliva (about 1 minute) and then spit it into a second container. Again add 2 Tbls. water. Now when the iodine is added to the cracker, it will be a much lighter shade of blue-gray. The lighter color indicates that there is less starch in the cracker. Their saliva has changed some of the starch into sugar.

Weekly Problem

Answers: Left table -- 1350 calories Right table -- 775 calories.

Writing for Science

Challenge your students to use their imaginations as they visualize being swallowed and traveling down the digestive tract. Remind them that the esophagus actually pushes the food down to the stomach and that the stomach squeezes and churns it. Ask them what they will see, hear, and feel as they move along WHY-FLY's digestive system. After they have finished their reports, you may wish to extend the experience by showing them The Magic School Bus[R] For Lunch or the old classic movie Fantastic Voyage.

Challenge

See TN Level B -- CHALLENGE. As an extension, have them measure the distance down the yarn to each organ and mark it with masking tape. (See box above.)

Puzzle

Answer: eleven hundred pounds.

Level D

Main Concepts: The stomach is just a small part of a long "food tube" that digests food and turns it into energy. The muscular walls of your stomach grind the food you eat. Digestive chemicals help break down the food in your digestive tract even more. The digested food eventually passes into your blood to be carried to all the parts of your body.

Vocabulary

ACROSS: 2) energy 4) digestion 6) stomach 7) teeth DOWN: 1) food 3) esophagus 5) mouth.

Weekly Lab

Adult supervision required. See TN Level C -- WEEKLY LAB. In addition, have your students chew the third cracker for 2 minutes before adding the water and iodine. The iodine indicator will now appear very light gray or not at all.

Weekly Problem

Answers: Left table -- 1380 calories Right table -- 795 calories.

Writing for Science

Challenge your students to use their imaginations as they visualize being swallowed and traveling down the digestive tract. Remind them that the esophagus actually pushes the food down to the stomach and that the stomach squeezes and churns it. Ask them what they will see, hear, and feel as they move along WHY-FLY's digestive system.

Challenge

The total length of the digestive tract is 5 to 6 times one's height. A child's "food tube" is between 20 and 24 feet, and an adult's is between 26 and 30 feet. Use yarn or string to measure a length of yarn 6 times the height of each child. Your students should mark the yarn with masking tape at the location of each organ as they measure along the length of their yarn.

Puzzle

Answer: eleven hundred pounds.

Level E

Main Concepts: The stomach is just a small part of a long "food tube" that digests food and turns it into energy. Food travels from your mouth, through your esophagus, to your stomach. The food then passes through the intestines where it is absorbed into the blood. Digestive chemicals are made in every part of your digestive tract.

Vocabulary

ACROSS: 1) teeth 4) saliva 5) stomach 7) small intestine 8) burp DOWN: 2) esophagus 3) digestion 6) fuel.

Weekly Lab

In this lab, your students will simulate the action of the stomach and see the effect that adding specific chemicals can have on the breakdown of fats and oils. Have them knead their bags until the water has dissolved the cracker and sugar. After 5 minutes, have them note what has happened to the cooking oil in Bag 2. (It will separate out from the other dissolved food and float to the top. This is what happens in the stomach to fatty, greasy foods you eat.) Tell your students that this food is not "passing into the small intestine." Have them add a few drops of liquid dishwashing detergent (representing digestive chemicals like bile from the liver) and mix it into the oily food. This time the oil will stay mixed - and their food would now be able to pass into the small intestine.

Weekly Problem

Answers will vary according to the individual foods chosen. Your students should choose at least 1 food from each part of the menu to create a meal. Remind them that this would be just I of their 3 daily meals. If their food choices add up to more than 1000 calories (more than half the recommended daily calorie intake), they should consider at which other meal or snack they could cut back on calories. Ask them if they think it is a good idea to eat fast food regularly. As an extension, ask them: What is the highest calorie meal they can make, if they choose one food from each category? (taco salad (905) + broccoli and cheese potato (400) + milkshake (320) + Frosty (340) = 1965 calories, almost a full day's worth of calories.) What is the lowest calorie meal? (cheese pizza (398) + mashed potatoes and gravy (71) + diet soft drink (2) + frozen yogurt (110) = 581 calories (... though they may wish to skip the potatoes in this combination!)

DID YOU KNOW??

Your stomach is not where you think it is. It's up high -- right behind the bottom rib on your left side.

Writing for Science

Challenge your students to use their imaginations as they visualize being swallowed and traveling down the digestive tract. Remind them that the esophagus actually pushes the food down to the stomach and that the stomach squeezes and churns it. Ask them what they will see, hear, and feel as they move along WHY-FLY's digestive system. After they have finished their reports, you may wish to extend the experience by showing them the old classic movie Fantastic Voyage.

Challenge

The total length of the digestive tract is 5 to 6 times one's height. A child's "food tube" is between 20 and 24 feet, and an adult's is between 26 and 30 feet. Use yarn or string to measure a length of yarn 6 times their height. Your students should mark the yarn with masking tape at the location of each organ as they measure along the length of their yarn.

Puzzle

Answers: eleven hundred pounds, twelve to thirty-six hours.

Level F

Main Concepts: The stomach is just a small part of a long "food tube" that turns food into energy. Digestive chemicals are produced in every part of your digestive tract. Food travels from your mouth through your esophagus to your stomach and into your intestines, where it is absorbed into the blood. Your blood then carries it throughout your body.

Weekly Lab

Lab A: See TN Level E - WEEKLY LAB. After observing the bags for 3 minutes, pour the contents_of both bags into a glass or jar through a coffee filter in a funnel (one can be made by cutting a soft drink bottle in half and using the neck-end for the funnel and the base for the cup.) This demonstrates how the tiny liquefied food passes through the intestines and into the blood, while undigested food is dried out and passed through the large intestine to exit the body. Lab B: Adult supervision required. (Note: This lab uses tincture of iodine to test for the presence of starch in food. Iodine is a skin antiseptic for external use only. It is poisonous and can stain skin and clothing if not used carefully. Remind your students to use care when handling iodine solutions. Small bottles of iodine antiseptic can be purchased at drugstores. Do not purchase de-colorized iodine. Betadine[R] solution will also work.) In this lab, your students will see how saliva reduces the amount of starch in a saltine cracker using iodine as a chemical indicator. If you add iodine to foods that contain starch (bread, pasta, potatoes, rice, or crackers, for instance), the iodine will turn from its orangy-brown color to a dark blue-black. Have your students crush a cracker in a cup (a zip-top bag will work well, too) and add 2 Tbls. water. When 10 drops of iodine are added, the mixture will appear dark blue to black. Have your students chew a second saltine long enough to mix it thoroughly with saliva (about I minute) and then spit it into a second container. Again add 2 Tbls. water. Now when the iodine is added to the cracker, it will be a much lighter shade of blue-gray. The lighter color indicates that there is less starch in the cracker. Their saliva has changed some of the starch into sugar. Have your students chew the third cracker for 2 minutes before adding the water and iodine. The iodine indicator will appear very light gray or not at all.

DID YOU KNOW??

Your liver makes over 500 different chemicals.

Weekly Problem

Answers will vary according to individual foods chosen. Your students should choose at least I food from each part of the menu to create a meal. Remind them that this would be just i of their 3 daily meals. If their food choices represent more than 50% of the recommended daily calorie intake, they should consider at which other meal or snack they could cut back on calories. Ask your students if they think it is a good idea to eat fast food regularly. As an extension, ask them: What is the highest calorie meal they can make, if they pick one food from each category? (taco salad (905) + broccoli and cheese potato (400) + milkshake (320) + Frosty (340) = 1965 calories, 98.25% of their day's calories.) What is the lowest calorie meal? (cheese pizza (398) + mashed potatoes and gravy (71) + diet soft drink (2) + frozen yogurt (110) = 581 calories, 29.05% of their day's calories (... though they may wish to skip the potatoes in this combination!)

Writing for Science

Challenge your students to use their imaginations as they visualize being swallowed and traveling down the digestive tract. Remind them that the esophagus actually pushes the food down to the stomach and that the stomach squeezes and churns it. Ask them what they will see, hear, and feel as they move along WHYFLY's digestive system. After they have finished their reports, you may wish to extend the experience by showing them the old classic movie Fantastic Voyage.

Challenge

ACROSS: 1) teeth 4) saliva $) stomach 7) small intestine 8) burp DOWN: 2) esophagus 3) digestion 6) fuel.

Puzzle

Answers: twelve to thirty-six hours, eleven hundred pounds.

DID YOU KNOW??

To eat a clam, a starfish pokes its stomach out its mouth and into the clamshell. when it is finished eating, it swallows its stomach again!

DID YOU KNOW??

Your empty stomach is about as big as a large sausage. A full stomach can hold almost half a gallon of food and drink.

WEEKLY RESOURCES

Helpful Sources for Planning Your Science Weekly Classroom Activities

Recommended Resources

* Parker, Steve. Food and Digestion. New York: Franklin Watts, 1990

* Parker, Steve. How the Body Works. Pleasantville, NY: Reader's Digest, 1994

* Rockwell, Lizzy. Good Enough to Eat: A Kid's Guide to Food and Nutrition. New York: Harper Collins Publishers, 1999

* VanCleave, Janice. Food and Nutrition for Every Kid. New York: John Wiley & Sons, Inc., 1999

Internet Resources

Your Gross & Cool Body -- http://yucky.kids.discovery.com/noflash/body/pgOOO126.html

Ask Dr. Universe (search for "stomach') -- http://druniverse.wsu.edu/search.asp

Animated movie, quiz, and facts (click on "digestion'*) --http://www. brainpop.com/health/seeall.html

Stomach Pictures and Facts (click on the digestive system picture) -- http://www.innerbody.com/htm/body.html

Mad Scientist Network (search for stomach) -- http://www, madsci.org

Voyage Through the Digestive Tract -- (for older students) -- http: / / arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion/

One Meal in the Life Of A Stomach -- (for older students) --

http://arbl.cvmbs.colostate.edu/hbooks/pathphys /digestion/stomach/onemeal.html

DID YOU KNOW?? While You read this, your stomach will replace half a million stomach lining cells

Materials Needed for Issue 6 - Crystals

Pre-A - dark plastic plates (with 3 sections), magnifying glasses, water, Epsom salt, a large container,

spoons, measuring cups, small cups, (optional- glitter)

A - same as above, plus scissors, glue, powdered sugar

B - dark plastic plates (with 3 sections), magnifying glasses, water, Epsom salt, powdered sugar,

spoons, measuring cups, small cups, (optional - hangers, yarn, glitter, scissors)

C, D - dark plastic plates (with 3 sections), magnifying glasses, water, Epsom salt, powdered sugar,

spoons, measuring cups, small cups, tape, scissors, small mirrors

E - dark plastic plates (with 3 sections), magnifying glasses, water, Epsom salt, table salt, powdered

sugar, spoons, measuring cups, small cups, toothpicks, mini-marshmallows

F- same as above, plus graph paper and colored pencils

Level E

Rumble, gurgle, growl! Your stomach is telling you you're hungry! Everyone needs to eat. Do you know why? Food provides your body with the fuel it needs to think, move, play, work, and live. Your stomach is just a small part of a long "food tube" that turns the foods you eat and drink into energy. This process is called digestion.

Making Energy

To get energy from food, your body has to grind your food into tiny bits. So digestion really starts in your mouth. Your teeth and tongue break up your food when you chew and mix it with watery saliva. When you swallow, the food is pushed down your esophagus and into your stomach. Your stomach is a sack made of strong muscles with muscular doors at each end. It churns and squeezes your chewed-up food. Your stomach also makes chemicals that help break down the food even more.

Stomach Noises

If you haven't eaten in a while and you think about food, your stomach may "growl." This is just your stomach muscles beginning to churn, getting ready for new food to arrive. They are squeezing the air you swallowed with your last meal. The scientific word for the growling noise your stomach makes is borborygmus (bor ba RIG mas). Sometimes the air escapes up your esophagus. Then out comes a burp! Other times, it may move along with your food and make gurgling noises farther along your digestive tract. Excuse you!!

Beyond the Stomach

From your stomach, the food moves into your small intestine where more digestive chemicals are added by your liver and pancreas. These chemicals help break down proteins, fats, and oils from foods like meat, eggs, and nuts. As the soupy food slowly travels along, the spongy walls of your small intestine absorb the food and pass it into your bloodstream. Your blood cells carry this fuel to every part of your body. Any undigested food travels through your large intestine and exits your body at the other end of your "food tube."

DID YOU KNOW??

When you are nervous, you may feel "butterflies" in your stomach. Blood has left your stomach and gone to your brain and muscles to help you handle the situation.

DID YOU KNOW??

Stomach acid is so strong your stomach needs a new lining every 3 days!

DID YOU KNOW??

While you read this, 1 your stomach will replace half a million lining cells!

DID YOU KNOW??

Your stomach is not where you think it is. It's up high -- right behind the bottom rib on your left side.

DID YOU KNOW??

A bite of swallowed food is called a bolus. It means "ball" in Latin.

DID YOU KNOW??

A swallow of water takes 2 seconds to reach your stomach. A bite of hamburger takes about 10 seconds.

Vocabulary

Solve this puzzle.

ACROSS

1. Your -- chop up food when you chew.

4. When you chew, your food mixes with --.

5. Your -- is a sack made of muscles.

7. Food goes from your stomach into your --.

8. If air escapes up your esophagus, you --.

DOWN

2. The tube from your mouth to your stomach.

3. The process of how your body turns food into energy is called --.

6. Food provides -- for your body.

[ILLUSTRATION OMITTED]

DID YOU KNOW??

Your empty stomach is about as big as a large sausage.

DID YOU KNOW??

A full stomach can hold almost half a gallon of food and drink. At holiday dinners, it can stretch to hold almost twice as much!

DID YOU KNOW??

Small birds can digest their food in less than 30 minutes! Bigger birds take about 10 hours and people can take a few days.

Weekly Lab

What happens in your stomach and intestines?

You need: 2 zip-top bags, 2 sugar cubes, 2 saltine crackers, water, cooking oil, dish detergent

Step 1: Put a sugar cube, a cracker, and 1/4 cup water into a bag. Press it closed. Make sure you squeeze most of the air out of the bag as you close it!

Step 2: Knead the bag with your hands for 2 minutes. What happens to the food?

Step 3: Repeat Steps 1 and 2, but this time add 1/4 cup of cooking oil. Let the bags sit for 5 minutes.

* What happens to the oil?

Step 4: Add a few drops of dish detergent to the second bag and shake.

* Now what happens to the oil?

* How is this like your digestive system?

DID YOU KNOW??

The Soupy food in your stomach is called Chyme.

Weekly Problem

If you're an average 10 to 14 year old, you should eat about 2000 calories a day. (Calories are how we measure the amount of energy in foods.) Put together a fast food meal you'd like and find out how many calories it has.

Be sure to choose at least 1 food from each category.
Main Dishes
 calories

McDonald's[R] Big Mac[R] 500
Burger King[R] Fish Fillet 495
Taco Bell[R] taco salad 905
KFC[R] chicken sandwich 482
Pizza Hut[R] thin cheese
 pizza (2 slices) 398

Drinks

Soft drink (12oz.) 190
Diet soft drink 2
Orange juice (12 oz.) 160
McDonald's[R] chocolate
 milkshake (10.4 oz.) 320
1% lowfat milk (8 oz.) 102
Whole milk (8 oz.) 150

Side Orders

McDonald's[R] medium fries 320
Wendy's[R] broccoli and
 cheese potato 400
Burger King[R] onion rings 339
KFC[R] mashed potatoes and
 gravy 71

Desserts

McDonald's[R] apple pie 260
Wendy's[R] small Frosty 340
Baskin-Robbins'[R]
 strawberry frozen yogurt 110
Dairy Queen[R] chocolate
 sundae 300


My Meal:

Number of Calories:

Writing For Science

Dr. Frank Furter has invented a new kind of technology to investigate stomach trouble. His machine can shrink you down to the size of a pea! Get ready to see what is making WHY-FLY feel so funny inside. He is about to swallow you and your equipment. Write a descriptive report about each part of WHY-FLY'S "food tube."

What do you think Dr. Furter should call his new Invention?

DID YOU KNOW??

Birds have no teeth. instead they have an extra stomach that has tiny rocks in it to help grind up their food.

Challenge

Your stomach is just a small part of your digestive system. How long is your whole digestive tract?

You need:

a large ball of yarn or string masking tape a pen

Measure out some yarn so it is as long as you are tall. Now make it 6 times as long. This is the length of your digestive tract.

Use tape to mark these lengths on your string.
mouth 4 inches
esophagus 10 inches
stomach 4 inches
small intestine 18 feet
large intestine 5 feet
colon 4 inches
rectum 5 inches
anus the end


DID YOU KNOW??

Your liver makes over 500 different chemicals.

Puzzle

Use the code to answer these questions.

[ILLUSTRATION OMITTED]

How much food does a grown-up eat in 1 year?.

[ILLUSTRATION OMITTED]

How long does it take to completely digest a meal?

[ILLUSTRATION OMITTED]

DID YOU KNOW??

Cows eat foods that need a lot of digesting. They have 4-part stomachs!

DID YOU KNOW??

Your mouth makes about 1 1/2 quarts of saliva each day.

DID YOU KNOW??

When you eat a big meal, blood goes to your stomach to help digest it. Your body warms up with all that blood deep inside, making you feel sleepy.

DID YOU KNOW??

A big meal stay in your stomach for as long as 5 hours.
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Title Annotation:exercises and experiments that help students learn about the stomach and digestion
Publication:Science Weekly
Date:Oct 27, 2000
Words:6433
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