Transcript The Digestive System

The Digestive
System
A guide to Chapter 16
Digestion of Food
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Food must be broken down into
nutrients in a process known as
digestion.
The breaking down of food into
simpler substances for use by the
body is the work of the digestive
system.
Types of Digestion
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Chemical Digestion: The digestion by
enzymes and other chemicals.
Enzymes: are chemicals that control
chemical reactions in the body.
Mechanical Digestion: The physical
action of breaking down food into smaller
parts (chewing).
Absorption: When nutrients and water are
absorbed through the villi and blood
vessels.
Steps of Digestion
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The Mouth:
Mechanical Digestion: chewing.
Chemical Digestion: Saliva contains
ptyalin an enzyme that breaks down
starch and changes it into sugar.
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Esophagus
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Means “to carry what is eaten”.
Lined with mucus.
Peristalsis: powerful waves of
muscle contractions that pushes the
food downward to the stomach.
Stomach
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Chemical Digestion: Gastric Juices
contains the enzyme pepsin,
hydrochloric acid and mucus.
Pepsin and HCl break down proteins.
Mechanical Digestion: Muscle
contractions and peristalsis.
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Secondary Organs
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These organs help in digestion. They
also have other roles in the body.
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Liver
Gallbladder
Pancreas
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Liver
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The body’s largest and heaviest
internal organ.
Produces bile
Bile breaks up large fat molecules.
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Gallbladder
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Small organ under the stomach.
Stores bile produced by the liver.
Releases bile through a duct or tube
as the food moves into the small
intestine.
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Pancreas
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Soft, triangular organ located
between the stomach and the small
intestine.
Produces pancreatic juices which is
a mixture of several enzymes.
Pancreatic juices break down
proteins, starches and fats.
Produces insulin, which controls the
body’s sugar levels.
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Small intestine
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2.5 centimeters in diameter, 6 meters
long.
Most chemical digestion takes place
in the beginning of the small
intestine.
Digested food is absorbed through
the villi into a network of blood
vessels.
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Large Intestine
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Water is absorbed here.
Helpful bacteria live in the large
intestine and make vitamin K and B
complex.
6.5 centimeters in diameter and 1.5
meters long.
Rectum stores waste products.
Anus is the opening that releases the
solid wastes.
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The End
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By Mrs. Scibelli
Prentice Hall,
Exploring Life Science
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