Transcript Digestive System - ESC-2

Digestive
System
Nutrients
• Substances in food that provide raw
materials and energy the body needs to
live
• Our digestive system turns the
chemical energy in these nutrients into
energy we can use
Functions of the Digestive
System
• Digests food into molecules the body
can use (physical or chemical change)
• Absorbs nutrient molecules and carries
them around the body (physical
change)
• Eliminates waste material from unused
nutrients
Digestion
• body breaks down food into small
nutrient molecules
– mechanical
– chemical
Mechanical Digestion
• Food is physically broken down into
smaller pieces
• Begins in the mouth
– Teeth chewing/tearing
– Movement of
smooth muscles
Chemical Digestion
• Chemicals produced by the body break
foods into their smaller nutrients
– mouth
– stomach
Absorption
• Process by which nutrient molecules
pass through the wall of your digestive
system into your blood
– The lining of the small intestine is covered
in villi that aid in absorption
Elimination
• Materials that are not absorbed leave
the body as waste
• The waste material left over after food
is digested must leave the body to
prevent illness
Which is not a function of the
digestive system?
a)
b)
c)
d)
Breaking down food into
molecules the body can
use
Absorbing food
molecules into the blood
to deliver to the body
Changing waste into
molecules the body can
use
Eliminating undigested
waste from the body
Organs of the Digestive System
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•
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Mouth
Esophagus
Stomach
Small intestine
Large intestine
Rectum
Anus
Pancreas
Gall Bladder
Liver
Mouth
• Digestion begins in the mouth
– Mechanical – teeth
– Chemical - saliva
Esophagus
• Muscular tube that connects your
mouth to your stomach
– moves food down into your stomach
using involuntary muscle
contractions (peristalsis)
– Lined with mucus that
allows food to slide down
The Stomach
• J-shaped muscular pouch
• Most mechanical digestion takes place
in the stomach
• Chemical digestions also takes place
– Stomach secretes digestive juice
(enzymes) that break down food
• Average adult stomach holds 2 liters
• Mucus keeps the acids from burning a
hole in your stomach
Stomach
Modeling
• Place the marble in the end of the tube
and squeeze it down into the balloon.
Modeling
• What do you think this could be a model
of?
– What is the tube? esophagus
– What is the balloon? stomach
– What is the marble? food
– What is the soap? saliva and mucus
Which is not an example of
mechanical digestion?
a) Teeth chewing food
b) Tongue breaking up
food
c) Smooth muscles in
stomach churning
food
d) Hydrochloric acid
breaking down
proteins
Small Intestine
• Where most of the chemical digestion
takes place
• Where most of the absorption takes
place
• Covered in villi which
enlarge the surface area
Small Intestine
a) Most digestion happens here.
b) Intestinal juice (full of enzymes)
breaks down food.
c) Digestive Helpers
• Liver, Gall bladder, Pancreas
d) Digested food is absorbed
through the villi into a network of
blood vessels that carry the
nutrients to all parts of the body.
e) By the time food leaves the small intestine, it is
empty of all nutrients except water.
Small Intestine
The villi increase the
surface area that can
absorb nutrients
Where does most digestion take
place?
a)
b)
c)
d)
Mouth
Stomach
Small intestine
Liver
Liver
• Breaks down medicines and other
chemicals
• Produces bile that breaks up fat
particles
• The gall bladder
stores bile
Pancreas
• Produces enzymes that flow into the
small intestine
• Secretes insulin
• Causes diabetes when it does not make
insulin
Large Intestine
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•
•
•
Last section of the digestive tract
Food spends 18-24 hours here
Where water is absorbed
Vitamins B & K are made by bacteria in
the large intestine
Rectum and Anus
• Rectum – end of the large intestine,
forms the solid waste
– elimination
• Anus – muscular opening at the end of
the rectum
– elimination
Which cell parts are like the
digestive system?
Which one makes energy?
mitochondria
Which one allows materials to pass in and out?
cell membrane
Which one helps get rid of waste?
lysosomes
The Digestive System Interacts
with:
• muscular system (smooth
muscle) to move and digest food
• respiratory system to provide
oxygen
• circulatory system to move
nutrients