Transcript File - Mr. Coach Risinger 7Y Science

Digestion breaks food into
very small pieces, most of
which are energy rich
molecules. These energy rich
molecules are small enough
to pass through the wall of
the digestive tube into the
rest of the body. .
Adapted from Amherst Regional Public Schools & ADAM Images
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Digestion begins the moment food
enters the mouth. Here the teeth
break the food and grind it into
small bits. This is called mechanical
digestion.
As the teeth chew the food, saliva
pours into the mouth from
the salivary glands and is mixed with
the food by the motion of the
tongue, cheeks, and lips.
Enzymes in the saliva begin to
digest some of the carbohydrates by
chemically breaking them into small
sugars. This is called chemical
digestion.
Saliva also moistens the food, thus
making it easier to swallow.
Adapted from Amherst Regional Public Schools & ADAM Images
are like factories that
produce the saliva used
to moisten your mouth,
begin digestion, and
help protect your teeth
from decay.
 Saliva has enzymes that
begin to break
carbohydrates into
sugars and it moistens
food so it slips down
the esophagus easier.
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Adapted from Amherst Regional Public Schools & ADAM Images
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When swallowed, food
passes into the part of the
digestive tube called the
esophagus.
Food passes quickly through
the esophagus aided by
slippery mucus on the inside
of the tube.
From this point on, small
wavelike movements, or
contractions, by the walls
of the digestive tube move
food along from one organ
to another. These wavelike contractions are
called peristalsis.
Adapted from Amherst Regional Public Schools & ADAM Images
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The stomach is an elastic muscular
bag which mechanically churns
(peristalsis) the food into a thick
liquid, called chyme (sounds like
Kime).
In addition, stomach glands
secrete acid and enzymes into the
stomach which chemically breaks
the large food molecules into tiny
molecules.
Mucus is also secreted to help
protect the stomach wall from
being digested by the acid and
enzymes.
From here, food gradually is passed
into the small intestine.
Adapted from Amherst Regional Public Schools & ADAM Images
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The impressive length of the
small intestine (about 6-7
meters) helps it complete the
important jobs of digestion
and absorption.
The first job of the small
intestine is to finish breaking food
into energy rich molecules. The
small intestine gets assisted by the
secondary organs:
the liver, gallbladder, and
the pancreas
The second job of the intestine is
to absorb the energy rich molecules
before the chyme gets to
the large intestine. These
molecules are small enough to
move out of the digestive tube and
be absorbed into the body.
Adapted from Amherst Regional Public Schools & ADAM Images
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To aid absorption the inside of
the small intestine is folded
up. On the surface of all these
folds are villi making the
surface area of the inside of
the small intestine about 600
times greater than the
outside.
Each of the folds is covered
with small villi. They look like
countless balloons attached to
the inside of the small
intestine. Inside each villi is a
capillary bed that carries away
all the nutrients that are
absorbed by the villi.
Adapted from Amherst Regional Public Schools & ADAM Images
The job of the large
intestine is to
gradually absorb water.
 The undigested foods
are now wastes and are
turned into solids which
are passed from the
body by excretion.
 The large intestine is
1.5-2 meters long,
waste material can
take about 10 hours to
pass through it.
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This is what
the inside of
your large
intestine
looks like..
Adapted from Amherst Regional Public Schools & ADAM Images
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The Liver is the largest organ
and has many, many important
functions in the body:
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It helps digestion by making bile
Removing Toxins
stores nutrients
Makes cholesterol for cell
membranes
The Gall Bladder is a small
pear-shaped organ just below
the liver that stores bile from
the liver. When food is
digested, the gallbladder
releases bile into the small
intestine where it is able to
help dissolve fats.
Adapted from Amherst Regional Public Schools & ADAM Images
The Pancreas
produces enzymes and
bases which it releases
into the beginning of
the small intestine.
 The enzymes finish
breaking down
carbohydrates and
proteins
 The bases neutralize
stomach acid so it
doesn't hurt the
intestines.
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Adapted from Amherst Regional Public Schools & ADAM Images
MECHANICAL
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Mechanical
Digestion: physically
breaking food into smaller
and smaller pieces by
chewing, churning and
squeezing.
A Physical Change
CHEMICAL
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Chemical Digestion: when
special chemicals called
enzymes and acids, break
food and molecules into
smaller and smaller pieces.
Bonds are broken
A Chemical Change
Adapted from Amherst Regional Public Schools & ADAM Images
 Images
by A.D.A.M. Images taken from
Medline Plus
<http://www.nlm.nih.gov/medlineplus/>
 A.D.A.M. Images
http://www.adamimages.com/Home
 Content from: Amherst Regional Public
Schools, 170 Chestnut Street Amherst, MA
01002, 2012.
<http://www.arps.org/USERS/ms/kellye/7th
%20grade/Human%20Body/Digestion/index.h
tm>
Adapted from Amherst Regional Public Schools & ADAM Images