Transcript Introduction to the Digestive System

The Digestive System
Grade 11 Biology
Table of Contents
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Introduction to the Digestive System
What is Digestion?
2 Phases of Digestion
4 Components of Digestion
The Organs of Digestion
Introduction to the
Digestive System

The digestive system
is an organ system that
ingests food, breaks it
down into smaller
chemical units, and
absorbs the nutrient
molecules.
What is Digestion?
 Digestion
is the mechanical and
chemical breakdown of food into
molecules small enough for the body to
absorb.
2 Phases of Digestion
1.
2.
Physical Digestion – begins in the mouth
where the food is chewed
Chemical Digestion – occurs in the mouth
and the stomach
4 Components of Digestion
1.
2.
3.
4.
Ingestion – the intake of nutrients
Digestion – the breakdown of organic
molecules
Absorption – the transport of digested
nutrients to body tissues
Egestion – the removal of materials from
food that the body cannot digest
The Organs of
Digestion
Mouth
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Physical digestion begins
Food is chewed into a bolus and mixed with
saliva
Initial carbohydrate digestion
Esophagus
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Peristaltic
contractions move
the food from the
mouth to the
stomach through
the esophagus.
Stomach
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Food storage
Initial protein
digestion
Small Intestine
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Site of the majority of
digestion and
absorption
 Digestion of proteins,
carbohydrates, and
lipids
 Villi increase surface
area of small intestine
for absorption
Pancreas
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Releases enzymes
into the small
intestine to aid in
digestion
Liver
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Produces bile salts
which emulsify fats
 Storehouse for
glycogen and vitamins
 Detoxifies many
substances in the body
Gall Bladder
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Stores bile salts
Large Intestine
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Stores food wastes
long enough to
reabsorb water
 Houses bacteria which
use waste materials to
synthesize vitamins
Credits
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Nelson Biology, Bob Ritter, Nelson Canada, 1993.
http://www.bayerpharmana.com/children/RON/digest/chrd0106.asp
http://central.vislab.usyd.edu.au/gallery/vrml/tour/ingal/cy
ber_anatomy/HTML/gallBladder.html
http://health.upenn.edu/~surgery/clin/gi/gallblad.html
http://www.digestivedisorders.org.uk/leaflets/pancreax.htm
http://www.mts-stl.org/kw.organ.smintestine.phtml
http://www.amaassn.org/insight/gen_hlth/atlas/newatlas/digest.html