The Facts on File Illustrated Guide to the Human Body: Digestive System

113 Pages·2005·7.18 MB·english

by  Diagram Group

THE FACTS ON FILE
ILLUSTRATED GUIDE TO
THE HUMAN BODY
DIGESTIVE
SYSTEM
THE DIAGRAM GROUP
The Facts On File Illustrated Guide to the Human Body:
Digestive System
Copyright © 2005 The Diagram Group
Editorial: Lionel Bender, David Harding, Denis Kennedy,
GordonLee, Jamie Stokes, Barbara Taylor
Scientific consultant: Stephen Rudd
Design: Anthony Atherton, Richard Hummerstone,
Lee Lawrence, Kim Richardson, Ben White
Illustration: Pavel Kostal, Kathleen McDougall
Picture research: Neil McKenna
Indexer: Jane Parker
All rights reserved. No part of this book may be reproduced or
utilized in any form or by any means, electronic or mechanical,
including photocopying, recording, or by any information storage or
retrieval systems, without permission in writing from the publisher.
For information contact:
Facts On File, Inc.
132 West 31st Street
New York NY 10001
Library of Congress Cataloging-in-Publication Data
The Facts On File illustrated guide to the human body. Digestive Note to the reader
system / The Diagram Group.
This book is not intended
p. cm.
to serve as a medical
Includes index.
ISBN 0-8160-5984-5 (hc : alk. paper) textbook for either
1. Gastrointestinal system—Juvenile literature. I. Title: Digestive physicians or patients.
system. II. Diagram Group. The information and
QP145.F23 2005
advice it contains should
612.3—dc22
not be used or relied upon
2004022926
Set ISBN: 0-8160-5979-9 without consulting the
advice of a qualified
Facts On File books are available at special discounts when physician. The publishers
purchased in bulk quantities for businesses, associations,
disclaim any responsibility
institutions, or sales promotions. Please call our Special Sales
for the accuracy of the
Department in New York at 212/967-8800 or 800/322-8755.
information or advice
You can find Facts On File on the World Wide Web at that this book contains
http://www.factsonfile.com and any responsibility for
any consequences that
Printed in the United States of America
may result from any use or
EB Diagram 10 9 8 7 6 5 4 3 2 1 reliance thereon by
the reader.
This book is printed on acid-free paper.
Contents
Introduction:About this book 4 Small intestine structure 58
Small intestine function 60
SECTION1 Small intestine absorption 62
DIGESTIVE SYSTEM Appendix and membranes 64
Introduction 6 Large intestine 66
Digestive organs 8 Rectum and anus 68
Digestion key words and facts 10 Lower digestive tract disorders 1 70
Food’s journey 12 Lower digestive tract disorders 2 72
How digestion works 14
Movement of food 16 SECTION5
Alimentary canal wall 18 LIVER & PANCREAS
Waste removal 20 Introduction 74
Liver structure 76
SECTION2 Liver function 78
NUTRIENTS & DIET Gallbladder and bile 80
Introduction 22 Pancreas 82
Calories and diets 24 Pancreatic juices 84
Eating problems 26 Liver disorders 86
Reducing weight 28 Pancreas and gallbladder disorders 88
Malnutrition and special diets 30
Digestive disorders 32 SECTION6
URINARYSYSTEM
SECTION3 Introduction 90
MOUTH &GULLET Kidney structure 92
Introduction 34 Nephrons 94
The tongue 36 Urine and urine flow 96
The teeth 38 Bladder and urethra 98
Dental hygiene 40 Urinary disorders 100
Salivary glands 42
Pharynx and esophagus 44
Swallowing 46 Glossary of the human body 102
Upper digestive tract disorders 48 Web sites to visit 108
Index 109
SECTION4
STOMACH &GUT
Introduction 50
Stomach structure 52
How the stomach works 54
Stomach juices 56
Introduction
4
This book is a concise, illustrated guide to the There are six sections within the book. The
anatomy, physiology, well-being, and first section surveys the digestive system and
disorders of the human digestive system. It outlines the process of digestion. The second
has been written and illustrated specially for section looks at food and the body’s needs for
students and laypeople interested in medicine, nutrients. Sections 3 and 4 focus on the
health, fitness, and first aid. The subject is components of the digestive tract, and section
dealt with in clear steps, so that the reader can 5 deals with organs linked with digestion. The
steadily acquire a good overall understanding. last section describes the urinary system,
Explanatory texts, diagrams, illustrations, which works in conjunction with the
captions, and fact boxes are combined to help digestive system. Within each section,
readers grasp important information at a discussion and illustration of the structure and
glance. A glossary of scientific and jargon function of the anatomical parts are followed
words defines medical terms in everyday by principles of healthcare, fitness, and
language. A list of Web sites provides links to exercise. These are followed by a survey of the
other relevant sources of information, and the main disorders and diseases affecting the
index enables quick access to articles. region. Information is presented as double-
page topics arranged in subsections.
Human body systems
This book is one of eight
titles in THE FACTS ON
FILE ILLUSTRATED
GUIDE TO THE HUMAN
BODY series, which looks
at each of the major body
systems in turn. Some
of the titles in the series
include more than one
system. The skeletal and
muscular systems, and
the blood and lymphatic
systems, for example,
work in conjunction and
so are treated together.
There is a separate title
for human cells and
genetics, which are the
building blocks and
underlying chemistry of Skeletal and Brain and Heart and
all body systems. Muscular Systems Nervous System Circulatory System
ABOUT THIS BOOK
5
Section 1: DIGESTIVE SYSTEM follows the Section 6: URINARYSYSTEM examines how
passage of food from the mouth to the anus, the waste products of chemical processes in
and shows how foodstuffs are broken down. the body are filtered from the blood, collected,
Section 2: NUTRIENTS & DIET analyzes the then eliminated.
calorific and nutrient content of foods and
gives guidelines on a balanced diet. This book has been written by anatomy,
Section 3: MOUTH & GULLET focuses on the physiology, and health experts for non-
mechanical and early chemical breakdown of specialists. It can be used:
foods. • as a general guide to the way the human
Section 4: STOMACH &GUT features the body functions
major chemical processes of digestion and the • as a reference resource of images and text for
absorption of essential nutrients. use in schools, libraries, or in the home
Section 5: LIVER&PANCREAS looks at how • as a basis for examination preparation for
organs linked to the digestive tract aid students of human biology, medicine,
digestion and how the products of digestion nursing, physiotherapy, and general
are processed and utilized. healthcare.
Digestive The Senses Respiratory Reproductive Cells and M
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Introduction
6
The digestive system is basically a long
tube that breaks down food so it can Position of
be absorbed into the body. Its main digestive system
feature is the alimentary canal, which in the body
measures about 30 feet (9 m) from
Esophagus
mouth to anus and includes the
●
esophagus, stomach, small and
Stomach
large intestines, and rectum. Also ●
contributing to the digestive process
Intestines
are various accessory digestive organs: ●
the teeth, tongue, salivary glands,
liver, gallbladder, and pancreas.
Digestive system parts The digestive
Mouth cavity Here the teeth, tongue, and system forms the
salivary glands process food for swallowing. major part of the
Esophagus This is the alimentary canal abdominal region,
between the lower pharynx (throat) and the below the head
stomach. Swallowed food is moved through and thorax.
it by rhythmic muscular contractions known
as peristalsis.
Stomach This enlarged section of the
alimentary canal churns, disinfects, and starts
digesting food, producing chyme, a semifluid extending from the ileum to the rectum. It is
mixture. subdivided into the cecum (from which the
Sphincters These are rings of smooth muscle appendix projects), and the ascending,
that contract to close an orifice. They include transverse, descending, and sigmoid colons.
the pyloric sphincter (between the stomach Rectum This tube extends from the sigmoid
and duodenum) and two anal sphincters. colon, and ends at a narrow orifice, the anus.
Digestive juices Saliva and juices secreted in Liver The body’s largest solid organ, the liver
the stomach, small intestine, and pancreas lies in the upper right part of the abdomen. Its
contain enzymes for digesting specific food complex chemical activities include secreting
substances. the emulsifying substance bile,
Small intestine This convoluted tube, about and storing vitamins and glycogen
21 feet (6.5 m) long, connects the stomach (a carbohydrate produced from glucose).
and the large intestine. It is subdivided into Gallbladder This sac stores bile, releasing
the duodenum, jejunum, and ileum. The it via the cystic duct and common bile duct
small intestine is the part of the alimentary into the duodenum.
canal where most digestion occurs. Pancreas This endocrine gland secretes
Large intestine Also called the colon, this is a insulin and pancreatic juice into
broad tube about 5 feet (1.5 m) long, the duodenum.
SECTION 1: DIGESTIVE SYSTEM
7
Digestive system
Salivary glands
●
●
Teeth
Stomach
●
Liver
●
Gallbladder
●
Pancreas
Small intestine ●
Duodenum ●
Jejunum
●
Ileum
Colon
●
●
●
Cecum
●
Appendix Rectum
●
Anus M
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Digestive organs
8
The digestive system
The digestive system consists of the or lymph vessels). The digested
group of organs involved in the and absorbed substances are then
processes by which food is digested transported around the body to be
(broken down into simpler substances) used for energy and for rebuilding
and absorbed (taken up by the blood and repairing cells and tissues.
Alimentary canal organs
The alimentary canal—or
gastrointestinal (GI) tract—consists
of several organs.
Mouth Esophagus
Mouth
●
Here, food is chewed into smaller Pharynx Stomach
pieces, mixed with saliva, and formed ●
into a rounded ball, or “bolus.”
Pharynx (throat)
Propels the bolus of food from
the mouth to the esophagus. ●
Esophagus (gullet)
Pushes food down to the stomach
by means of waves of muscular
●
contraction.
Stomach Small
Churns food into even smaller pieces, intestine
●
mixes the food with gastric juices to
●
digest food (especially protein), and
Large ●
regulates an even flow of food into the
intestine
small intestine. Acid in the stomach ●
kills bacteria.
Small intestine Anus
Made up of the duodenum, jejunum, ●
and ileum. Part of the system where
most digestion takes place and water remaining waste into a soft solid
and nutrients are absorbed into the (feces), which is a mixture of
blood and lymph systems. indigestible remnants, unabsorbed
Large intestine water, and millions of bacteria.
Removes salt and water from Anus
undigested food and turns the Opening for feces to exit the body.
SECTION 1: DIGESTIVE SYSTEM
9
Accessory organs
The teeth and the tongue physically the pancreas, and the gallbladder also
break the food up into smaller pieces. produce digestive juices that chemically
As food is chewed, it is mixed with break down food. The liver
saliva from the salivary glands. These is the largest gland in the body, and
make the digestive juice saliva. The liver, weighs 3–4 pounds (1.4–1.8 kg).
Accessory digestive organs
The accessory digestive organs aid
Tongue
digestion in various ways.
Teeth
These chop up food, making it easier Teeth ● ● ●
to digest by exposing more surface ●● ●
Salivary
area of the food for digestive enzymes
glands
to act on.
Tongue
Helps the teeth to chew food and
shape it into the bolus, ready to be
Liver
swallowed.
Salivary glands
Produce saliva, which lubricates food, ●
making it easier to swallow. Saliva
Gallbladder
begins converting starch to sugar. ● Pancreas
●
Liver
Converts nutrients from food into
usable substances and stores them
until they are needed.
Gallbladder
Stores and concentrates bile from the
liver and releases it when needed to
help with fat digestion.
Pancreas
Secretes many digestive enzymes into
the small intestine and neutralizes
stomach acid. Insulin, which helps the
Digestion fact
body to utilize sugar, is passed directly
• The salivary glands produce up to
into the bloodstream from
3 pints (1,600 ml) of saliva every day.
the pancreas. M
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