1. Chapter 3 DIGESTION, ABSORPTION, AND METABOLISM

2. Digestion and Absorption Biochemically, “you are what you eat” is true! Food and fluid taken into the body is broken down into smaller components so it can be used by the body. Copyright 2012, John Wiley & Sons Canada, Ltd.

3. Digestion and Absorption Copyright 2012, John Wiley & Sons Canada, Ltd.

4. Organ Systems of the Body Copyright 2012, John Wiley & Sons Canada, Ltd.

5. Overview of the Digestive System Digestion: process of breaking food into components small enough to be absorbed by the body Absorption: process of taking substances into the interior of the body Gastrointestinal tract: hollow tube consisting of the mouth, pharynx, esophagus, stomach, small intestine, large intestine and anus Transit time: amount of time it takes food to pass the length of the GI tract Feces: body waste, including unabsorbed food residue, bacteria and dead cells Copyright 2012, John Wiley & Sons Canada, Ltd.

6. Overview of the Digestive System Copyright 2012, John Wiley & Sons Canada, Ltd.

7. Structure of the Gut Wall Copyright 2012, John Wiley & Sons Canada, Ltd.

8. Digestive Secretions Digestion inside the GI tract is assisted by digestive secretions. Mucus: viscous material produced by goblet cells; mucus moistens, lubricates and protects the GI tract Enzymes: protein molecules that speed up chemical reactions; enzymes are not changed during reactions Copyright 2012, John Wiley & Sons Canada, Ltd.

9. Digestive Enzymes Copyright 2012, John Wiley & Sons Canada, Ltd.

10. Digestive Hormones Copyright 2012, John Wiley & Sons Canada, Ltd.

11. GI Tract’s Role in Immune Function The GI tract plays an important role in protecting the body from infection. The GI tract limits the absorption of toxins and disease-causing organisms. Some cells of the immune system are present in the GI tract: Phagocytes Lymphocytes Antibodies Copyright 2012, John Wiley & Sons Canada, Ltd.

12. Digestion and Absorption The mouth is the entry point for food into the digestive tract. Saliva in the mouth moistens food. Saliva contains salivary amylase, which helps to break down carbohydrates and lysozymes, which help to inhibit bacterial growth in the mouth. Chewing mechanically breaks food down, increasing the surface area in contact with digestive enzymes. Copyright 2012, John Wiley & Sons Canada, Ltd.

13. Digestion and Absorption Pharynx and Epiglottis Copyright 2012, John Wiley & Sons Canada, Ltd.

14. Digestion and Absorption Esophagus Copyright 2012, John Wiley & Sons Canada, Ltd.

15. Digestion and Absorption Stomach Copyright 2012, John Wiley & Sons Canada, Ltd.

16. Digestion and Absorption Copyright 2012, John Wiley & Sons Canada, Ltd.

17. Digestion and Absorption The brain is involved in digestion and absorption. Copyright 2012, John Wiley & Sons Canada, Ltd.

18. Digestion and Absorption The gallbladder, liver and pancreas are involved in digestion and absorption. Copyright 2012, John Wiley & Sons Canada, Ltd.

19. Digestion and Absorption The large intestine does not participate in digestion. The large intestine can absorb water and some vitamins and minerals. The large intestine contains the colon and the rectum. Water, nutrients and fecal material may spend up to 24 hours in the large intestine. Copyright 2012, John Wiley & Sons Canada, Ltd.

20. Absorption Copyright 2012, John Wiley & Sons Canada, Ltd.

21. Digestion and Absorption of a Deal Copyright 2012, John Wiley & Sons Canada, Ltd.

22. Common Digestive Problems Copyright 2012, John Wiley & Sons Canada, Ltd.

23. Common Digestive Problems Copyright 2012, John Wiley & Sons Canada, Ltd.

24. Alternate Feeding Methods If an individual cannot take adequate food or fluid by mouth:  Enteral or tube feeding  TPN: total parenteral nutrition Copyright 2012, John Wiley & Sons Canada, Ltd.

25. Transport of Nutrients Around the Body: The Cardiovascular System Copyright 2012, John Wiley & Sons Canada, Ltd.

26. Transport of Nutrients Around the Body: The Hepatic Portal Circulation Copyright 2012, John Wiley & Sons Canada, Ltd.

27. Metabolism of Nutrients Metabolic pathways are a series of reactions needed to transform food into a final product that can be used by the body. Catabolic pathways release energy trapped in chemical bonds. Energy from catabolic reactions is converted into ATP. ATP is the energy currency of the cell. Copyright 2012, John Wiley & Sons Canada, Ltd.

28. ATP Copyright 2012, John Wiley & Sons Canada, Ltd.

29. Metabolizing Nutrients: Cellular Respiration Copyright 2012, John Wiley & Sons Canada, Ltd.

30. Elimination of Metabolic Wastes: Body Organ System Copyright 2012, John Wiley & Sons Canada, Ltd.

31. Elimination of Metabolic Wastes: The Kidneys Copyright 2012, John Wiley & Sons Canada, Ltd.

32. Copyright Copyright © 2012 John Wiley & Sons Canada, Ltd. All rights reserved. Reproduction or translation of this work beyond that permitted by Access Copyright (The Canadian Copyright Licensing Agency) is unlawful. Requests for further information should be addressed to the Permissions Department, John Wiley & Sons Canada, Ltd. The purchaser may make back-up copies for his or her own use only and not for distribution or resale. The author and the publisher assume no responsibility for errors, omissions, or damages caused by the use of these programs or from the use of the information contained herein.. Copyright 2012, John Wiley & Sons Canada, Ltd.