Download The Digestive System

The Digestive System
Function of the Digestive
System
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Breaks up food physically and
chemically.
Stores food for a short period of time.
Absorbs the digested foods and passes
them into the circulatory system.
Stores and eliminates undigested food
from the body.
Types of Digestion
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Mechanical: The physical breakdown of
food by non-enzyme means.
Chemical: The use of enzymes to
breakdown food.
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Changes food into a NEW and smaller
substance that can travel into the cells. It is
chemically different.
Enzymes
Enzymes work best
at a certain pH and
body temperature.
If the body gets too
hot or too cold, the
enzymes will not work
and we get sick or die
Enzymes have a specific
shape and can only do
one special job.
This is called the LOCK
AND KEY THEORY
because they only FIT
into one job
Regents Question
Experiments revealed the following information
about a certain molecule:
— It can be broken down into amino acids.
— It can break down proteins into amino
acids.
— It is found in high concentrations in the
small intestine of humans.
This molecule is most likely
(1) an enzyme
(2) an inorganic compound
(3) a hormone
(4) an antigen
Regents Answer
(1) an enzyme
Parts of the Digestive System
Human Digestion
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The Mouth
Esophagus
Stomach
Liver and Pancreas
Small Intestine
Large Intestine
Rectum
Anus
Mouth
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Both chemical and
mechanical digestion occurs
here.
The teeth and tongue will
chop and mix the food.
The salivary glands will add
enzymes to begin the
chemical process.
The tongue will direct the
moisten food into the gullet.
Esophagus
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The gullet is the opening
to the esophagus.
It is 12 inches long and
connects the mouth with
the stomach.
Contains smooth
muscles which contract,
pulling the food
downward (peristalsis).
Stomach
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Stores and digests food.
pH of 1-2
Enzyme: pepsin which acts on
proteins, rennin on dairy
HCl is needed to activate
pepsin.
Mucus covers the inner lining
to prevent the acid from
eating the tissue.
The pylorus connects the
stomach to the small intestine.
Regents Question
The diagram below represents two molecules
that can interact with each other to cause a
biochemical process to occur in a cell.
Molecule A╞ ╢Molecule B
Molecules A and B most likely represent
(1) a protein and a chromosome
(2) a receptor and a hormone
(3) a carbohydrate and an amino acid
(4) an antibody and a hormone
Regents Answer
(2) a receptor and a hormone
Small Intestine
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It is divided into 3 parts: duodenum,
jejunum, and ileum.
Most digestion takes place here
It is here that all the organic
material are broken down into their
monomers.
They are absorbed by structures
called villi and sent into the blood.
The undigested food is passed on
to the large intestine.
Liver, Pancreas, and Gall
Bladder
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These are accessory organs.
The liver produces bile which is needed
to help digest fat.
The gall bladder stores the bile.
The pancreas produces enzymes need
to finish digesting the main organic
foods. It also produces insulin.
Large Intestine
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Also known as the colon
Absorbs excess water
from the unused food.
E. coli will produce
vitamin K.
Stores solid waste in the
area called the rectum.
Absorption
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The small intestine is longer
but thinner in diameter than
the large intestine
The small intestine is
lined with villi which
increase the surface
area
Nutrients are
absorbed into the
blood through the villi
and travel the body to
be used by the cells
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