Chapter 3 DIGESTION, ABSORPTION, AND METABOLISM. Digestion and Absorption Biochemically, “you are...

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.

Copyright 2012, John Wiley & Sons Canada, Ltd.

Digestion and Absorption


Organ Systems of the Body


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


Overview of the Digestive System


Structure of the Gut Wall


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


Digestive Enzymes


Digestive Hormones


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


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.


Digestion and Absorption Pharynx and Epiglottis


Digestion and Absorption Esophagus


Digestion and Absorption Stomach



The brain is involved in digestion and absorption.


Digestion and Absorption The

gallbladder, liver and pancreas are involved in digestion and absorption.


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.


Absorption


Digestion and Absorption of a Deal


Common Digestive Problems


Alternate Feeding Methods If an individual cannot take adequate food or

fluid by mouth: Enteral or tube feeding TPN: total parenteral nutrition


Transport of Nutrients Around the Body: The Cardiovascular System


Transport of Nutrients Around the Body: The Hepatic Portal Circulation


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.


ATP


Metabolizing Nutrients: Cellular Respiration


Elimination of Metabolic Wastes: Body Organ System


Elimination of Metabolic Wastes: The Kidneys


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.

.


Chapter 3 DIGESTION, ABSORPTION, AND METABOLISM. Digestion and Absorption Biochemically, “you are...

Documents

Transcript of Chapter 3 DIGESTION, ABSORPTION, AND METABOLISM. Digestion and Absorption Biochemically, “you are...