Transcript Nutrition and Digestion - Jamestown School District

Nutrition and Digestion
Chapter 38
Nutrition
The process by which organisms get food and
break it down for metabolism
6 Essential Nutrients
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Proteins (organic)
Carbohydrates (organic)
Fats (organic)
Vitamins (organic)
Minerals (inorganic)
Water (inorganic)
Remember…
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Autotrophsorganisms capable of
making their own food
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Heterotrophsorganisms that must obtain
food from their
environment
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The Human Digestive System
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Also called the alimentary canal or the
gastrointestinal tract
Diagram of Human Digestive
System
1.
2.
4.
5.
3.
6.
8.
7.
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10.
11.
Digestive system organs
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The alimentary canal (digestive tract) of the human is
made up of the following ordered sequence. Food passes
through these structures:
-oral cavity or mouth
-pharynx
-esophagus
-stomach
-small intestine
-large intestine
Accessory organs
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Other organs/glands are important for
disgestion. Food does not pass through these
structures:
-gall bladder
-liver
-pancreas
-appendix
Functions of all organs and structures in
the human digestive system
I. Oral cavity or mouth
2.
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Lining of the mouth is
epithelial tissue:
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3.
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2.
3.
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Salty
Sweet
Sour
Bitter
Stimulation of taste buds
results in secretion of saliva
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4.
Secretes mucous
(protection)
This starts chemical
digestion
Carbohydrate digestion
begins in the mouth
(amylase)
 Teeth begun mechanical
digestion
II. Pharynx
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Food passes through this narrow region and
goes into the esophagus.
III. Esophagus
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Tube that connects the pharynx to stomach.
Food enters by “wavelike” motion of smooth
muscle contractions called peristalsis.
IV. Stomach
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sac like
contains gastric juice
 This is water, hydrochloric acid, mucus, and the
enzyme pepsin.
Protein digestion begins here.
Bacteria are destroyed by acid environment
Peristalsis is occurring here.
Ulcers may develop here.
V. Small intestine
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About 20-25 feet long
Contains folds or villi
that increase the surface
area
Villi___________
Small intestine con’t
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Most absorption of nutrients into the blood
stream occurs here.
Most chemical digestion is occurring here.
Lipid digestion occurs here.
Peristalsis is continuing.
The small intestine receives secretions from
the liver and pancreas.
VI. Large intestine (colon)
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Water absorption
Feces formation
Appendix located at end of large intestine
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This is a vestigial organ-it no longer has a useful
function.
VII. Liver
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Largest organ
Functions:
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Secretes bile
Produces urea
Breakdown of worn out
red blood cells
Breakdown of proteins
into amino acids
Removes sugar from
blood
Stores sugar as glycogen
Liver con’t
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Excessive use of alcohol and some drugs can
cause damage to the liver
Bile produced by liver is stored in gallbladder.
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Function is to break up lipids
Therefore people without a gallbladder must watch
their fat intake.
VIII. Pancreas
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Functions
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Hormone secretion. (hormone-chemical in blood
for regulation)
Secretes enzymes into small intestine for digestion.
Regulates blood sugar levels.
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Cells inside pancreas called the Islets of Langerhans…
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Secretes glucagon when blood sugar is too low
Secretes insulin when blood sugar levels are too high
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Malfunctions of the Digestive Tract
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Ulcers-erosion of the lining in the stomach
Constipation-large intestine emptied with difficulty.
Caused by too much water absorption in large
intestine
Diarrhea-disturbance characterized by decreased water
absorption and watery feces. May result in severe
dehydration.
Appendicitis-inflammation of appendix
Gall stones-accumulation of cholesterol in gall bladder