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Transcript
Digestive
Organ
Mouth
Pharynx /
Esophagus
Stomach
Liver
Gall Bladder
Pancreas
Small Intestine
Large Intestine
Rectum
Anus
Function
Digest Food
Chemicals
Absorb Food
Produced
Present
Absorb Water (inc. enzymes)
The mouth is the beginning of the digestive
system, and, in fact, digestion starts here
before you even take the first bite of a
meal.
The smell of food triggers the salivary
glands in your mouth to secrete saliva
(contains the ENZYME AMYLASE), causing
your mouth to water. When you actually
taste the food, saliva increases.
Once you start chewing and breaking the
food down into pieces small enough to be
digested other mechanisms come into play.
More saliva is produced to begin the process
of chemically breaking down food.
Also called the throat, the pharynx is
the portion of the digestive tract that
receives the food from your mouth.
Branching off the pharynx is the
esophagus, which carries food to the
stomach.
The act of swallowing takes place in the
pharynx. The food then enters the
esophagus.
The esophagus is a muscular tube. Food
is pushed through the esophagus and
into the stomach by means of a series of
contractions called peristalsis.
The stomach is a hollow organ, or
"container," that holds food while it is
being mixed with enzymes that continue the
process of breaking down food into a usable
form.
Cells in the lining of the stomach secrete a
strong acid and protease enzymes that are
responsible for the breakdown process.
When the contents of the stomach are
sufficiently processed and have changed to
the consistency of liquid or paste, they are
released into the small intestine.
The liver has multiple functions, but its main
function within the digestive system is to
process the blood containing the nutrients
absorbed from the small intestine.
Bile made in the liver and secreted into the
small intestine also plays an important role
in digesting fat.
In addition, the liver is the body’s chemical
"factory." It takes the raw materials
absorbed by the intestine and makes all the
various chemicals the body needs to
function.
The liver also detoxifies potentially harmful
chemicals found in the blood.
The gallbladder is a storage sac for excess
bile. Bile made in the liver travels to the
small intestine via the bile ducts.
If the small intestine doesn't need it, the
bile travels into the gallbladder where it
awaits the signal from the intestines that
food is present.
Bile serves two main purposes:
• First, it helps absorb fats in the diet.
• Secondly, it carries waste from the
liver that cannot go through the
kidneys.
Among other functions, the pancreas is the
chief factory for digestive enzymes.
These are secreted into the first segment of
the small intestine.
These enzymes break down protein, fats, and
carbohydrates.
The pancreas also makes insulin, secreting it
directly into the bloodstream. Insulin is the
chief hormone for metabolizing sugar.
• Carbohydrate enzyme – carbohydrase
• Fat enzyme – lipase
• Protein enzyme - protease
The small intestine is a 22-foot long muscular tube
(split into 3 sections) that breaks down food using
enzymes released by the pancreas and bile from
the liver.
Peristalsis is also at work here, moving food
through and mixing it with digestive secretions
from the pancreas and liver. The first part is
largely responsible for the continuous breakingdown process, with second and third part mainly
responsible for the absorption of nutrients into
the bloodstream.
Contents of the small intestine start out semisolid, and end in a liquid form after passing
through the organ. Water, bile, enzymes, and
mucous contribute to the change in consistency.
Once the nutrients have been absorbed and the
leftover-food residue liquid has passed through
the small intestine, it then moves on to the large
intestine.
The large intestine is a 6-foot long muscular tube
that connects the small intestine to the rectum. The
large intestine is a highly specialised organ that is
responsible for processing waste so that emptying
the bowels is easy and convenient.
Stool, or waste left over from the digestive process,
is passed through the colon by means of peristalsis,
first in a liquid state and then ultimately in a solid
form.
As stool passes through the large intestine, water is
removed. It normally takes about 36 hours for stool
to get through the large intestine. The stool itself is
mostly food debris and bacteria. These bacteria
perform several useful functions, such as synthesizing
various vitamins, processing waste products and food
particles, and protecting against harmful bacteria.
When the last section of the large intestine becomes
full of stool, or faeces, it empties its contents into
the rectum to begin the process of elimination.
The rectum is an eight-inch chamber that
connects the colon to the anus.
The rectum:
• Receives stool from the large intestine.
• Lets the person know there is a stool to
be evacuated.
• Holds the stool until evacuation happens.
When anything (gas or stool) comes into the
rectum, sensors send a message to the brain.
The brain then decides if the rectal contents
can be released or not. If they can, the
sphincters relax and the rectum contracts,
expelling its contents. If the contents
cannot be expelled, the sphincters contract
and the rectum accommodates so that the
sensation temporarily goes away.
The anus is the last part of the digestive
tract.
It is a 2-inch long canal consisting of the
pelvic floor muscles and the two anal
sphincters (internal and external).
It consists of the muscles that line the
pelvis (pelvic floor muscles) and two other
muscles called anal sphincters (internal and
external).
Three different enzymes break down the three main food groups:
Amylase
Carbohydrates  Sugars
Produced in:
• Salivary Glands / Pancreas /Small Intestine
Protease
Proteins  Amino Acids
Produced in:
• Stomach / Pancreas / Small Intestine
Lipase
Fats  Fatty Acids + Glycerol
Produced in:
• Pancreas / Small Intestine