Transcript The Digestive System

The Digestive
System
Function: To
breakdown
food into
molecules
that can be
used by the
body for
growth,
repair, and
energy.
Form: Many
organs, and
digestive
enzymes.
The mouth
Teeth: Mechanical Digestion
Coated in enamal
Different teeth = different function
Incisors & Canines = bite, tear, rip
Molars & Premolars = chew
Tongue: Swallowing
Amylase: Digestive Enzyme
(chemical digestion)
Food is formed into a bolus (ball of
chewed food mixed with enzymes)
The Esophagus
Connects the mouth to
the stomach
Food moves by
peristalsis
Rhythmic contractions
of the smooth muscle
of the esophagus
The Stomach
Food enters through the cardiac
sphincter, a circular muscle at the top of
the stomach.
Mechanical digestion:
Churning and mixing
Chemical digestion: enzymes
Pepsin: Breaks down protein
HCl Hydrochloric-Acid: provides the
acidic environment that pepsin works
best in
Mucous membrane: protects stomach
from acid
Many folds of the stomach allow for
increased surface area and the ability to
stretch
Partially digested food leaves the
stomach through the pyloric sphincter
as chyme.
Small Intestine
Longest organ of digestion
Starts with the duodenum
Where digestion is
completed
Nutrients are absorbed by
Villi:
Digestive enzymes from
the pancreas, gall bladder,
and liver are added to the
small intestine
Food moves by peristalsis
Villi
Coat the
small
intestine
Increase
surface area
Increase
absorption
Liver, Gallbladder & Pancreas
Liver
makes bile
Gallbladder
store bile
Bile
Combination of salts
that emulsifies or
breaks down fat into
smaller droplets
Pancreas
adds enzymes and a
neutralizing solution
Produces hormones
that regulate blood
sugar levels (insulin)
The Large Intestine
Absorption of
water
Bacteria produce
important vitamins
(K)
Ends with the
rectum and anus
Mass peristalsis
pushes undigested
remains out of the
body.
How Do Bacteria Obtain Energy
Photosynthesis: Energy
obtained from the sun
Chemosynthesis:
Energy obtained by
digesting non living
substances (rock,
metals, sulfurs)
Heterotrophic: Energy
obtained by digesting
biotic substances by
creating secreting
powerful enzymes and
absorbing the nutrients
directly into the bacteria
cell.
Protozoan
Filter feed
Photosynthesis
Surrounding and
absorbing.
Many protozoan have
bacteria that aid in
digestion
Plants
Plants obtain their food by
photosynthesis
Energy from the sun
converts carbon dioxide
and water in to sugar and
oxygen
Water is drawn up by
roots and carbon dioxide
is absorbed by the leaves.
Chloroplast are the
organelles that
photosynthesize.
Fungus
Secrete a digestive
enzyme and then
absorb the digested
food into body
Digestion is external
Feed on dead, dying or
living organisms
Do not use
photosynthesis
Arthropods
Very simple plan
But similar to that of
mammals
Termites have protozoan
in there gut to help
digest wood.
Birds, Crocodiles, and
Earthworms
All have a gizzard like
organ to help grind
food.
Gizzards are filled
with stones
Dinosaurs also had
gizzards
Cows Stomach
Contains different
chambers to increase
effectiveness of
digestion
Bacteria very
important in digestion
of plant material.