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The Digestive System

pharynx

digestion

saliva

esophagus

stomach

small intestine

large

intestine

colon

Start with the CALIFORNIA STANDARDS

5 LS 2.c. Students know the sequential steps of digestion and the roles of teeth and the mouth, esophagus, stomach, small intestine, large intestine, and

colon in the function of the digestive system.

5 IE 6.i. Write a report of an investigation that includes conducting tests, collecting data or examining evidence, and drawing conclusions.

Look and Wonder

Continue your conversation about the digestive system with the Look and Wonder question. Ask:

How does your small intestine help you digest food?

Possible answer: Chemicals break down food into parts small enough to be absorbed.

Why do you think your intestines are so long?

Possible answer: to allow more surface area for all the nutrients to be absorbed

Tell students they will learn more about absorption during the Explore Activity.

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What is digestion?

digestion

digestion (di jes´chәn) The process by which food is broken down into usable substances.

Start with the CALIFORNIA STANDARDS

5 LS 2.c. Students know the sequential steps of digestion and the roles of teeth and the mouth, esophagus, stomach, small intestine, large intestine, and

colon in the function of the digestive system.

5 IE 6.i. Write a report of an investigation that includes conducting tests, collecting data or examining evidence, and drawing conclusions.

Discuss the Main Idea

Have students talk about digestion. Ask:

What are the first two steps in digestion, and where do these steps take place?

Possible answer: Food is broken down physically and chemically in the mouth.

Develop Vocabulary

digestion (di jesº ch әn) The process by which food is broken down into usable substances. (p. 122)

Digestion begins the moment you start to chew something.

- Scientific vs. Common Use Ask students to note unfamiliar scientific words they find in the dictionary definition of digestion.

Possible answers: substance, assimilate, alimentary canal, enzyme, chemical compounds

Discuss these new terms with students until they more fully understand the definition of digestion.

Critical Thinking

Are solids or liquids easier to digest?

Answer: Liquids are easier to digest because they don’t require physical digestion.

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What is digestion, pg. 122

Life Science: The Human Body

Name

Homeroom #

Date

Universal #

Science

Ch. 3, Lesson 2

pgs.122-128

Digestion:

Nutrients:

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What is digestion, pg. 122

Life Science: The Human Body

Name

Homeroom #

Date

Universal #

Science

Ch. 3, Lesson 2

pgs.122-128

What are the first two steps in digestion, and where do these steps take place?

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Life Science: The Human Body

Name

Homeroom #

Date

Universal #

Science

Ch. 3, Lesson 2

pgs.122-128

Organs of the Digestive System:

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Where does digestion begin?

esophagus

pharynx

teeth

tongue

salivary glands

saliva

pharynx

esophagus

saliva (sә´lī´vә) A watery fluid that moistens and softens food.

pharynx (fa´ringks) The part of the throat that connects the mouth to the digestive tube.

esophagus (i sä´fә gәs) A long muscular tube leading to the stomach.

Start with the CALIFORNIA STANDARDS

5 LS 2.c. Students know the sequential steps of digestion and the roles of teeth and the mouth, esophagus, stomach, small intestine, large intestine, and

colon in the function of the digestive system.

5 IE 6.i. Write a report of an investigation that includes conducting tests, collecting data or examining evidence, and drawing conclusions.

Discuss the Main Idea

Have students discuss how digestion starts. Ask:

What are two roles the tongue plays?

Possible answer: Taste buds detect flavors; moves food back toward the pharynx.

Develop Vocabulary

saliva (sәªlīºvә) A watery fluid that moistens and softens food. (p. 124)

Saliva helps digestion by chemically breaking down food.

- Word Origin Ask students to find the origin of saliva. (Answer: Latin saliva.) Have students use saliva in a sentence.

pharynx (faºringks) The part of the throat that connects the mouth to the digestive tube. (p. 125)

The pharynx is located just above the esophagus.

- Write pharynx, mouth, stomach, larynx, and esophagus on the board. Ask students to put them in the order in which they occur in the digestive system. mouth, pharynx, larynx, esophagus, stomach

esophagus (i säºfә gәs) A long muscular tube leading to the stomach. (p. 125)

Your esophagus is lined with mucus that helps food slide along.

- Word Origin Ask students to find the origin and meaning of the word part phago-. (Answer: Greek, phagein, to eat.) Have them relate it to the meaning of esophagus.

Reading Photos

What will most likely happen the baby teeth that are shown this X ray?

Clue: Observe the teeth below baby teeth in the photo.

Answer: The child will start losing his or her baby teeth and the adult teeth will start growing in.

Critical Thinking

What would happen if your salivary glands did not secrete saliva?

Answer: It would be harder to swallow food because the saliva softens and moistens the food. It also starts to break the food down chemically.

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Life Science: The Human Body

Name

Homeroom #

Date

Universal #

Science

Ch. 3, Lesson 2

pgs.122-128

Types of Teeth:

Where does digestion begin,

pg. 124

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Life Science: The Human Body

Name

Homeroom #

Date

Universal #

Science

Ch. 3, Lesson 2

pgs.122-128

Where does digestion begin,

pg. 124

What are two roles the tongue play?

Roles of the Tongue:

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Life Science: The Human Body

Name

Homeroom #

Date

Universal #

Science

Ch. 3, Lesson 2

pgs.122-128

Saliva:

Tongue:

Salivary Glands:

Pharynx:

Esophagus:

Where does digestion begin,

pg. 124-125

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Life Science: The Human Body

Name

Homeroom #

Date

Universal #

Science

Ch. 3, Lesson 2

pgs.122-128

Where does digestion begin,

pg. 124-125

Explain what happens when you put food in your mouth. Use the vocabulary words on page 124.

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Life Science: The Human Body

Name

Homeroom #

Date

Universal #

Science

Ch. 3, Lesson 2

pgs.122-128

What would happen if your salivary glands did not secrete saliva?

What happens after the bolus is swallowed?

Where does digestion begin, pg. 124-125

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How is food broken down further?

Bolus enters stomach

Stomach contracts to mix bolus

stomach

stomach (stә´mәk) The main digestive organ in most animals.

Start with the CALIFORNIA STANDARDS

5 LS 2.c. Students know the sequential steps of digestion and the roles of teeth and the mouth, esophagus, stomach, small intestine, large intestine, and

colon in the function of the digestive system.

5 IE 6.i. Write a report of an investigation that includes conducting tests, collecting data or examining evidence, and drawing conclusions.

Discuss the Main Idea

Have students talk about the functions of the digestive organs. Ask:

What happens after the bolus is swallowed?

Possible answer: After the esophagus moves the bolus down to the stomach, the food is broken down by chemicals to a thick, liquid. It is further broken down in the small intestine

Develop Vocabulary

stomach (stәºmәk) The main digestive organ in most animals. (p. 126)

The human stomach has three layers of muscles and glands that produce chemicals for breaking down food.

- Scientific vs. Common Use Introduce the idiom: I couldn’t stomach her unfriendly attitude. Ask students to make sense of this phrase based on what

they know about the stomach.

Possible answer: It means I can’t digest, process, or assimilate it; I can’t make it part of me.

small intestine (smôl inªtesºtәn) A coiled, tubelike digestive organ connected to the stomach. (p. 127)

Partially digested food is broken down into nutrients inside the small intestine.

- Word Origin Ask students to find the origin of intestine. (Answer: Latin, intus, within) Have students explain how this ancient meaning helps us understand the word.

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Life Science: The Human Body

Name

Homeroom #

Date

Universal #

Science

Ch. 3, Lesson 2

pgs.122-128

How is food broken down further, pg.126-127

Stomach:

Why does the stomach contract?

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How is food broken down further?

Small Intestine

villi

small intestine

small intestine (smôl in´tes´tәn) A coiled, tube like digestive organ connected to the stomach.

Start with the CALIFORNIA STANDARDS

5 LS 2.c. Students know the sequential steps of digestion and the roles of teeth and the mouth, esophagus, stomach, small intestine, large intestine, and

colon in the function of the digestive system.

5 IE 6.i. Write a report of an investigation that includes conducting tests, collecting data or examining evidence, and drawing conclusions.

Reading Photos

How are the inside of the small intestine and towel similar?

Clue: Compare the photos and read the captions to answer the question.

Answer: Both the loops in the fabric of the towel and the small intestine folds and villi increase the area for absorption.

Critical Thinking

Explain the steps of digestion with a diagram. Start with the stomach and end with the small intestine.

Answer: The drawing should show the stomach mixing the food, the liver adding bile to break down fat, the gall bladder storing extra bile, the pancreas adding digestive juices, and food being absorbed in the small intestine.

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Life Science: The Human Body

Name

Homeroom #

Date

Universal #

Science

Ch. 3, Lesson 2

pgs.122-128

How is food broken down further, pg. 126-127

Small intestine:

How are the inside of the small intestine and the folds of fabric in a towel similar?

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Life Science: The Human Body

Name

Homeroom #

Date

Universal #

Science

Ch. 3, Lesson 2

pgs.122-128

How is food broken down further, pg. 126-127

What happens to the nutrients right before they leave the small intestine?

Liver:

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Life Science: The Human Body

Name

Homeroom #

Date

Universal #

Science

Ch. 3, Lesson 2

pgs.122-128

How is food broken down further, pg. 126-127

Bile:

Gall bladder:

Pancreas:

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Life Science: The Human Body

Name

Homeroom #

Date

Universal #

Science

Ch. 3, Lesson 2

pgs.122-128

Explain the steps of digestion and what happens with a diagram. Start with the esophagus and end with the small intestine.

How is food broken down further, pg. 126-127

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What are the parts of the large intestine?

cecum

rectum

colon

large intestine

colon

large intestine (lärj in tes´tәn) A thick, tubelike organ that removes waste from the body.

colon (kō´lәn) The widest and longest part of the large intestine.

Start with the CALIFORNIA STANDARDS

5 LS 2.c. Students know the sequential steps of digestion and the roles of teeth and the mouth, esophagus, stomach, small intestine, large intestine, and

colon in the function of the digestive system.

5 IE 6.i. Write a report of an investigation that includes conducting tests, collecting data or examining evidence, and drawing conclusions.

Discuss the Main Idea

Have students talk about the last steps in the digestive process. Ask:

What happens after nutrients are absorbed into the bloodstream?

Possible answer: undigested particles are released into the large intestine and finally eliminated.

Are undigested particles bad for you?

Possible answer: Some are actually good for you. They clean out your small intestine as they are pushed through.

Develop Vocabulary

large intestine (lärj in tesºtәn) A thick, tubelike organ that removes waste from the body. (p. 128)

The large instestine is shorter and thicker than the small intestine.

- Word Origin Remind students that intestine comes from the Latin intus, meaning “within.”

colon (kōºlәn) The widest and longest part of the large intestine. (p. 128)

Some absorption of water and minerals takes place in the colon.

- Scientific vs. Common Use Ask students for the common definition of colon. (Answer: A punctuation mark [:]) Have students write sentences using the scientific definition of colon.

Critical Thinking

Do you think the large intestine has villi? Why or why not?

Answer: No, the large intestine only absorbs a small amount of water and minerals.

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Life Science: The Human Body

Name

Homeroom #

Date

Universal #

Science

Ch. 3, Lesson 2

pgs.122-128

What are the parts of the large intestine, pg. 128

Large intestine:

Cecum:

Colon:

Rectum:

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