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.
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3. Copyright 2010, John Wiley & Sons, Inc.
The digestive tract begins at the _________ and ends at the _______.
 a.
esophagus; small intestine
 b.
mouth; pancreas
 c.
esophageal sphincter; stomach
 d.
mouth; anus
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4. Overview of the Digestive System
Most of you is dedicated to breaking down food to nourish yourselves
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5. Digestion and Absorption
The brain is involved in digestion and absorption.
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6. Digestion and Absorption
Pharynx and Epiglottis
First place for food breakdown
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7. Digestion and Absorption
The mouth is the entry point for food into the digestive tract.
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.
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8. Copyright 2010, John Wiley & Sons, Inc.
Chewing is an important digestive function because it improves the functionality of
 a.
enzymes.
 b.
hormones.
 c.
mucus.
 d.
peristalsis.
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9. Digestion and Absorption
Esophagus
peristalsis
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10. 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
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11. Digestion and Absorption
Stomach
Viscous Mucosal layer protects the stomach
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12. Copyright 2010, John Wiley & Sons, Inc.
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
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13. Copyright 2010, John Wiley & Sons, Inc.
Digestive Enzymes
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14. Copyright 2010, John Wiley & Sons, Inc.
Digestive Hormones
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15. Copyright 2010, John Wiley & Sons, Inc.
Food moves through the digestive tract by wavelike contractions called a)
quickening. b)
the Heimlich maneuver. c)
peristalsis. d)
segmentation.
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16. Digestion and Absorption
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17. Digestion and Absorption
The gallbladder, liver and pancreas are involved in digestion and absorption.
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18. Copyright 2010, John Wiley & Sons, Inc.
Which of the following accessory organs releases its secretions into the GI tract?
Gallbladder
Pancreas
Salivary glands
All answer choices are correct
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19. Structure of the Gut Wall
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20. 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
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21. 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.
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22. Copyright 2010, John Wiley & Sons, Inc.
The primary site of nutrient absorption is the a)
liver. b)
large intestine. c)
stomach. d)
small intestine.
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23. Copyright 2010, John Wiley & Sons, Inc.
Absorption
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24. Digestion and Absorption of a Meal
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25. Transport of Nutrients Around the Body: The Cardiovascular System
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26. Transport of Nutrients Around the Body: The Hepatic Portal Circulation
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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.
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28. Copyright 2010, John Wiley & Sons, Inc.
ATP
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29. Metabolizing Nutrients: Cellular Respiration
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30. Elimination of Metabolic Wastes: Body Organ System
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31. Elimination of Metabolic Wastes: The Kidneys
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32. Copyright 2010, John Wiley & Sons, Inc.
The two major functions associated with the digestive system include digestion and
metabolism.
absorption.
circulation of nutrients in the blood.
excretion of metabolic waste products.
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