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The Digestive System
You are what you eat!
What is the function of the digestive
system?
• The digestive system has three main
functions:
1. It breaks down food into molecules the body
can use.
2. The digested molecules are absorbed into the
blood.
3. Wastes are eliminated from the body.
Important definitions
• Digestion: the process by which your
body breaks down food into small nutrient
molecules (protein, fat, carbohydrates,
vitamins, and minerals).
• Absorption: the process by which the
nutrient molecules pass through the walls
of your digestive system into your blood.
What are the major parts of the
digestive system and their function?
• Mouth: Digestion begins in the mouth.
Two types of digestion take place in the
mouth:
1. Mechanical: this is done with
your teeth, breaking the food
apart.
2. Chemical: the saliva in your
mouth starts to breakdown
starches (complex sugars).
Major parts and their function
• Esophagus: a muscular tube that
connects the mouth and the stomach.
Contraction of smooth muscles
(peristalsis) pushes the food toward the
stomach.
• Epiglottis: a small flap of tissue that seals
off the windpipe to prevent food from
entering the lungs.
Major parts and their function
• Stomach: mechanical and chemical
digestion occurs here. The stomach
squeezes (churns) the food, mixing it with
fluids. It also releases enzymes to
breakdown protein.
• Once the food is turned into liquid form, it
is ready for final digestion and absorption.
Major parts and their function
• Small intestine: this is where most of
chemical digestion takes place. It mixes
with enzymes and secretions produced in
three different organs.
• Liver: has many functions, but in
digestion the liver produces bile, a
substance that breaks down fat.
Major parts and their function
• Gallbladder: an organ that stores bile.
After eating, bile passes from here
through a tube to the small intestine.
• Pancreas: has many functions, but in
digestion produces enzymes that
breakdown fats, proteins, and starches.
These enzymes pass through a tube to
the small intestine.
Major parts and their function
• Large intestine: the last section of the
digestive system. The material entering
here has water and undigested food
(fiber). Water is absorbed and the
remaining material passes through the
rectum to the anus and out of the body.
http://videos.howstuffworks.com/discovery/28649assignment-discovery-breaking-down-digestionvideo.htm
What organs, in order, does the food pass
through during the digestive process?
•
•
•
•
•
Mouth
Esophagus
Stomach
Small intestine
Large intestine
http://videos.howstuffworks.com/hsw/17328-the-digestive-systemunderstanding-digestion-video.htm
http://kidshealth.org/kid/htbw/_bfs_DSmoviesource.html
What other systems work with the
digestive system?
• Circulatory: nutrient molecules are
absorbed by the blood and carried
throughout the body.
• Excretory: collects waste from digestion
and eliminates it from the body.
• Endocrine: the pancreas releases
enzymes during digestion.
The Digestive System
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odybasics/digestive_system.html