11/4/2011
Animal Digestion
Prepared by: Steve Guzman
Animals ingest their food in a variety of ways
Figure 1: Suspension
feeder; tube worm
filtering food through
its tentacle
Figure 2: Substrate feeder;
caterpillar
Figure 3: Fluid feeder; mosquito
Figure 4: Bulk feeder; grey heron
Chemical digestion:
digestion the
breakdown of large
organic molecules to
their components
Figure 5: Chemical digestion:
the breakdown of large
organic molecules of their
components
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Overview: Food processing occurs in four stages
Diagram 1: The four main stages of food
processing
Digestion occurs in specialized compartments
Diagram 2: Digestion in the gastrovascular
cavity of a hydra
Digestion occurs in specialized compartments (cont.)
Figure 6: Three
examples of
alimentary canals
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The human digestive system consists of an
alimentary canal and accessory glands
Diagram 3: The human
digestive system
Digestion begins in the oral cavity
Figure 7: The human
oral activity
After swallowing, peristalsis moves food through
the esophagus to the stomach
Diagram 4: The human swallowing reflex
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After swallowing, peristalsis moves food through
the esophagus to the stomach (cont.)
Figure 8: Peristalsis
moving a food bolus
down the esophagus
The Stomach
Diagram 5: The stomach
and its production of
gastric juice
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Digestive ailments include acid reflux and
gastric ulcers
Figure 9: Ulcer-causing
bacteria, Helicobacter pylori
Sources of Digestive Enzymes and Bile
Figure 10: The small intestine and
related digestive organs
Digestion in the Small Intestine
Table 1
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Absorption in the Small Intestine
Diagram 6: Structure of the small intestine
One of the liver’s many functions is processing nutrientladen blood from the intestines
Figure 11: The hepatic
portal system
The large intestine reclaims water and compacts
the feces
Figure 12: The relationship
of the small and large
intestine
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Evolutionary adaptation of vertebrate digestive
systems often relate to diet
Figure 13: The alimentary canal
in a carnivore (coyote) and an
herbivore (koala)
Chemical energy powers the body
Table 2
An animal’s diet must supply essential
nutrients
Figure 15: Obesity; a form of
malnourishment
Figure 14: Anorexia;
a form of
undernourishment
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Vegetarians must be sure to obtain all eight
essential amino acids
Figure 16: Essential
amino acids from a
vegetarian diet
A healthy diet includes 13 vitamins and many
essential minerals
Figure 17: Vitamin B12: a
coenzyme in nucleic acid
metabolism; maturation of red
blood cells
Figure 18: Calcium: Functions in
bone and tooth formation, blood
clotting, nerve and muscle function
What do food labels
tell us?
Figure 19: Whole wheat bread labels
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The human health problem of obesity
may reflect our evolutionary past
Figure 21: A mouse with a defect in a gene for leptin, an
appetite-suppressing hormone (left); a normal mouse
right (right)
Figure 20: Fat cells
from the abdomen
of a human
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