chapter 3 digestion, absorption, and metabolism. digestion and absorption biochemically, “you are...
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Chapter 3DIGESTION, ABSORPTION, AND METABOLISM
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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Digestion and Absorption
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Organ Systems of the Body
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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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Overview of the Digestive System
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Structure of the Gut Wall
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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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Digestive Enzymes
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Digestive Hormones
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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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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.
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Digestion and Absorption Pharynx and Epiglottis
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Digestion and Absorption Esophagus
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Digestion and Absorption Stomach
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Digestion and Absorption
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Digestion and Absorption
The brain is involved in digestion and absorption.
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Digestion and Absorption The
gallbladder, liver and pancreas are involved in digestion and absorption.
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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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Absorption
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Digestion and Absorption of a Deal
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Common Digestive Problems
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Common Digestive Problems
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Alternate Feeding Methods If an individual cannot take adequate food or
fluid by mouth: Enteral or tube feeding TPN: total parenteral nutrition
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Transport of Nutrients Around the Body: The Cardiovascular System
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Transport of Nutrients Around the Body: The Hepatic Portal Circulation
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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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ATP
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Metabolizing Nutrients: Cellular Respiration
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Elimination of Metabolic Wastes: Body Organ System
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Elimination of Metabolic Wastes: The Kidneys
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Copyright
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