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DIGESTIONDIGESTIONDIGESTIONDIGESTIONDIGESTION

The Inside StoryThe Inside StoryThe Inside StoryThe Inside StoryThe Inside Story

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SCENE 1 It�s All �Vores 1:20The world of mammals is all �vores�herbivores, carnivores, or omnivores.This musical introduction shows thatherbivores, carnivores, and omnivoreseat different types of food.

SCENE 2 Sink Your Teeth Into It! :30Cast member Stephanie demonstratesthat the process of digestion starts withthe teeth. How? By beginning to digestright before your eyes!

SCENE 3 Name That Tooth 2:15Cast member David examines the skullsand teeth of some animals to show howdifferent types of teeth are used to breakdown different types of food.

SCENE 4 The Big Breakdown 1:30Stephanie uses a large glass to repre-sent the stomach as she demonstratesthat sugars, starches, and proteins needdifferent kinds of chemicals to dissolvethem.

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� Digestion is a complex pro-cess involving a system ofmany organs of the bodyworking together.

� Digestion requires bothchemical and mechanicalprocesses.

In order for living things to getenergy from food, it must be bro-ken down into simple compoundsthat can be absorbed. This happensin a process called digestion, and itusually involves both chemical andmechanical processes. In mostmammals, digestion begins with theteeth. They rip and grind food intosmaller pieces. Then�in the stom-ach�water, acids, and enzymeschemically react with the food andbreak it down even further. As thefood passes through the small in-testine, most of the nutrients areabsorbed, and in the large intestine,water and salts are absorbed. Anyundigested solids are excreted.

In mammals, the layout of thedigestive tract may be somewhatsimilar, but the structure and func-tion of the teeth may be different.Herbivores, such as horses andcows, have flat teeth for grindingplant materials; carnivores, such astigers and bears, have sharp teethfor ripping meat; and omnivores,such as people, can eat both typesof food because they have sharpcanines for ripping and flat molarsfor grinding.

SCENE 5 Through the System 7:00Did you know your digestive system isvery much like a pig�s? David found outit�s true. While visiting biologist RonRochan and some students examining apig�s digestive system, David learnedthe role of each organ in the digestivesystem and how similar each is to thosein humans.

SCENE 6 Work Zone :30As Stephanie eats one of her favoritefoods, she�s not working hard but herdigestive system is. It�s breaking thefood down so her body can absorb thenutrients.

vocabulary: digestion, enzyme, protein, starch, acid, dissolve,carnivore, herbivore, omnivore, absorb

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TUNING INTUNING INTUNING INTUNING INTUNING INAsk students how long they think it takes food to be completely digested after they take a biteof it. (The time varies for different people, but food generally moves through the digestivesystem in about 20 hours.) Discuss suggestions, then have students watch the video to find outmore about what happens to the food they eat. Pause after Scene 3 and discuss how thedifferent kinds of teeth help break down different kinds of foods. Then resume viewing.

Ask students if they can explainwhat digestion is. Why is it important?(breaks food down so the body canabsorb essential nutrients) Where doesthe process of digestion begin? (Manystudents may think it�s in the stomach.Once they watch the video, they�ll un-derstand that digestion begins with theteeth and the saliva in the mouth.)

Can students think of any wayspeople help the digestive process evenbefore they eat food? (by cooking andcutting food)

Reinforce the concept that di-gestion is a complex process thatuses many organs working togetherin a system. On the chalkboard, listthe following organs: small intestine,liver, gall bladder, stomach, large in-testine, teeth, esophagus, pancreas,anus, rectum.

Ask students to createdigestive-system flow charts simi-lar to the one shown (right). You maywish to do this as a class or havekids work independently. If time per-mits, have students review the func-tion of each organ.

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WHAWHAWHAWHAWHAT TO DOT TO DOT TO DOT TO DOT TO DO:::::

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MATERIALS:(per class-for demonstration)� 2 clear glass 16-oz. jars� 10 sugarcubes� 5 tsps. granulated sugar� 2 spoons� 16 oz. water

(per 4 students)� five 6-oz. plastic cups� 20 oz. cool tap water� measuring cup� 1 miniature marshmallow� 1 shelled peanut� 1 chocolate drop or small chunk

of chocolate bar� 1 sugar cube� 1 plain cracker� 1 plastic straw� 1 watch with second hand

To let students discover thatdifferent foods dissolve in waterat different rates.

1. Place the sugar cubes in one jar and the granulated sugar in the other.Ask students to predict which will dissolve first if you pour 8 oz. ofwater in each jar and stir 10 seconds. (granulated sugar)

2. Divide the class into groups of 4, distribute materials and copies of theactivity sheet, �Breakin� Up is Hard to Do.�

3. Explain that the object of the activity is to see how water dissolvesdifferent foods. Then have groups place 1 food item in the bottom ofeach cup. Ask kids to rank each item in the order in which they think itwill dissolve. Number the items from 1 to 5, from fastest to slowest, andrecord these predictions on the activity sheet.

4. Ask groups to add 4 oz. of water to each of their cups. Have one memberwatch the time while another stirs each cup�s contents with a straw onceevery minute for 20 minutes.

5. Have students describe in Part 2 of the activity sheet how each fooditem looks after soaking for 20 minutes. Finally, have students rank thefoodsin the order in which they dissolved and record this on the activ-ity sheet. Are there any foods that didn�t dissolve at all? Why? (Usu-ally, sugars will dissolve first followed by the cracker [Carbohydrate.]The chocolate [fat] and the peanut [protein] show little change becausethey require acid and enzymes to help them dissolve.) How did the finalranking results compare with kids�predictions?

After completing the activity, re-view, with students water�s contribu-tion to digestion. (It can soften somethings and make them easier to digest.)What things other than water areneeded for digestion? (teeth, enzymes,acids, etc.) Why do people add soap towater when cleaning greasy dishes?(Water alone has a hard time dissolv-ing fats.) Why should people take timeto chew high-protein foods, such aspeanuts? (Without mechanical break-down first, they usually pass rightthrough the digestive system withoutdissolving.)

Remind students that technology puts science towork for people. For example, antacids help people get ridof indigestion. How? Encourage kids to find out. Havekids pour 6 oz. of vinegar in a plastic cup and dip in litmuspaper�it turns orange/pink, indicating acid. Drop 2 ant-acid tablets in the cup and allow them to completely dis-solve. Then dip in litmus paper�it doesn�t change colorbecause the antacid neutralized the acid (vinegar) thatcaused the indigestion.

Ask students to put themselves in the place of acarnivore, such as a tiger or bear, that lost its teeth todecay or in a fight. How would kids�as the carnivore�survive in the wild? Taking into account what they know

about digestion, have studentswrite humorous stories about howthey would hunt for food and howthey would eat their meals.

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