Download The Digestive System

The Digestive System (Do Not Copy)
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a system of organs that:
- takes in and breaks down food
- absorbs nutrients
- removes solid waste from the body
There are more similarities than differences
among animal digestive systems
The Human Digestive System
There are 4 stages of digestion in
humans:
1) Ingestion: taking in food (eating)
2) Digestion: physical and chemical
breakdown of food
a) physical: chewing action of
teeth and churning
action of stomach
2) Digestion (continued)
b) chemical: enzymes in saliva, stomach and small
intestine chemically break down food
into small molecules (nutrients)
 liver, gall bladder & pancreas release
substances (including enzymes) into
small intestine
The Human Digestive System
3)
Absorption:
nutrients, water, vitamins and minerals from the small
and large intestine are absorbed into the bloodstream
 then can travel to other cells in the body
4)
Egestion:
removal of solid waste products through the colon,
rectum and anus
The Human Digestive System
The Human Digestive System
esophagus
stomach
liver
gall bladder
pancreas
small
intestine
large
intestine
appendix
rectum
anus
Cool Facts
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(Do Not Copy)
Small intestine is lined with millions of villi
(folds of the membrane) to maximize
surface area for absorption
If all villi were unfolded, they would take up
the area of a tennis court
Large intestine is full of “good” bacteria that
help produce vitamins from nutrients
Our salivary glands produce
2 litres of saliva/day
Bacteria in our digestive system
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Herbivores have much
longer digestive systems
than carnivores of the
same size.
Why?
 Plant products are
more difficult to digest
 More time and
surface area needed
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Most fish are carnivores
Use teeth to grasp and swallow prey
(no physical digestion)
Long straight stomach allows fish to
swallow animals almost the same
size
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Pyloric caeca (where stomach and intestine meet)
carries out most digestion and absorption
Remaining nutrients absorbed in intestine with
egestion through anus
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Birds collect food in beak,
but little physical digestion
occurs there
Crop: special storage pouch
Food travels into first
stomach segment – digestive
juices added
Then into the gizzard that
contains small stones to
grind food
Absorption in intestine and
egestion through cloaca (allpurpose “hole”)
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Mouth is adapted to capture
prey
Long tongue is sticky and
moves very quickly to catch
prey
Two types of teeth in upper
jaw to hold prey as it is
swallowed (no physical
digestion)
Food can be held in gullet
(wide, elastic esophagus)
Rest is similar to human,
but egestion occurs through
cloaca
The Frog Digestive System
Esophagus
Liver
Gall bladder
Lungs
Pancreas
Stomach
Small Intestine
Spleen
Large Intestine
Cloacal vent
Cloaca
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Digestive System Comparison Worksheet