6.1 Digestion and Absorption

Essential Idea

• The structure of the wall of the small intestine allows it to move, digest and absorb food.

Understandings

1. The contraction of circular and longitudinal muscle of the small intestine mixes the food with enzymes and moves it along the gut.

2. The pancreas secretes enzymes into the lumen of the small intestine.

3. Enzymes digest most macromolecules in food into monomers in the small intestine.

4. Villi increase the surface area of epithelium over which absorption is carried out.

5. Villi absorb monomers formed by digestion as well as mineral ions and vitamins.

6. Different methods of membrane transport are required to absorb different nutrients.

Applications

1. Processes occurring in the small intestine that result in the digestion of starch and transport of the products of digestion to the liver.

2. Use of dialysis tubing to model absorption of digested food in the intestine.

Skills

1. Production of an annotated diagram of the digestive system (VIDEO).

2. Identification of tissue layers in transverse sections of the small intestine viewed with a microscope or in a micrograph.

Guidance

• Students should know that amylase, lipase and an endopeptidase are secreted by the pancreas. The name trypsin and the method used to activate it are NOT required.

• Students should know that starch, glycogen, lipids and nucleic acids are digested into monomers and that cellulose remains undigested.

• Tissue layers should include longitudinal and circular muscles, mucosa and epithelium.

Key Vocabulary

• • Peristalsis

    • Circular muscles (around the girth)

    • Longitudinal muscles (along the length)

  • Small intestine

    • Lumen (space within the tube)

  • Villi (small projections)

    • • Increase surface area for absorption

    • Dialysis tubing

    • Transverse section as seen in a micrograph

      • Muscles listed above

      • Mucosa

      • Epithelium

  • Pancreas

    • Pancreatic juice (released into small intestine)

      • Lipase (digests lipids)

      • Amylase (digests carbohydrates)

        • Unable to digest cellulose

      • Endopeptidase (digest proteins)

  • Liver

Textbook Reading and/or Activities

Click HERE for a pdf of chapter 6.

• Pages 285-291

  • Figure 6.1 (p.287)

  • Figure 6.2 (p.288)

  • TOK (p.290)

  • Exercises (p.291)

Notes

i-Biology Notes

A detailed set of notes, prepared by Stephen Taylor, examining U1-U6, A1 and S1.

i-Biology Study Questions (Not available)

A series of questions, prepared by Stephen Taylor, to help check your understanding of the IB learning expectations. This is VERY GOOD practice.

Bioknowledgy Notes

A detailed set of notes, prepared by Chris Paine, examining all of the IB learning expectations.

Bioknowledgy Study Questions (Not available)

A series of questions, prepared by Chris Paine, to help check your understanding of the IB learning expectations. This is VERY GOOD practice.

Learning Activities

Digestive System: Your Body's Fuel Factory

This interactive tutorial, prepared by National Geographic, will help you learn the digestive system's anatomy as well as better understand the processes of digestion and absorption.

Draw, Label and Annotate the Digestive System

This activity will challenge your ability to prepare a drawing as outlined in Skills 1 to the left.

Build a Body: Digestive System

This activity challenges you to identify the location of the different digestive structures within the human body.

Digestive System

A variety of "games", prepared by Anatomy Arcade, to help you better understand the structures and functions of the human digestive system.

Supplemental Reading

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