Thursday, 24 April 2014
Thursday, 17 April 2014
Introduction to GIT System
Where the food will go after eating?
Digestion is the breakdown of food into smaller components that can be
more easily absorbed and assimilated by the body. In the human digestive system, food enters the mouth and mechanical
digestion of the food starts by the action of mastication, and the wetting
contact of saliva. After undergoing
mastication and starch digestion, the food called a bolus will then travel down
the esophagus and into the stomach by the action of peristalsis. Gastric juice
in the stomach starts protein digestion.
After some time, the resulting thick liquid is called chyme and enters
the duodenum where it mixes with digestive enzymes from the pancreas, and then
passes through the small intestine, in which digestion continues. When the chyme
is fully digested, it is absorbed into the blood. Water and minerals are
reabsorbed back into the blood in the colon (large intestine) where the pH is
slightly acidic. Some vitamins, such as biotin and vitamin K produced by
bacteria in the colon are also absorbed into the blood in the colon. Waste
material is eliminated from the rectum during defecation.
Peristalsis
What
is Peristalsis?
A wave-like
muscular contractions of the alimentary canal or other tubular structures by
which contents are forced onward toward the opening.
Where
can Peristalsis occur?
-
Oesophagus
-
Small Intestine
-
Large Intestine
How
Peristalsis occur in Esophagus?
After food is
chewed into a bolus, it is swallowed and moved
through the esophagus. Smooth muscles contract behind the bolus to prevent it
from being squeezed back into the mouth. Then rhythmic, unidirectional waves of
contractions will work to rapidly force the food into the stomach. This process
works in one direction only and its sole purpose is to move food from the mouth
into the stomach.
Types of Peristalsis occur in Esophagus?
-
Primary
Peristaltic wave
-
Secondary
Peristaltic wave
What is the Primary peristaltic wave?
It occurs when the
bolus enters the esophagus during swallowing. The primary peristaltic wave forces the
bolus down the esophagus and into the stomach in a wave lasting about 8–9
seconds. The wave travels down to the stomach even if the bolus of food
descends at a greater rate than the wave itself, and will continue even if for
some reason the bolus gets stuck further up the esophagus.
What is the Secondary peristaltic wave?
In the event that the bolus gets stuck
or moves slower than the primary peristaltic wave (as can happen when it is
poorly lubricated), stretch receptors in the esophageal lining are stimulated
and a local reflex response causes a secondary peristaltic wave around
the bolus, forcing it further down the esophagus, and these secondary waves
will continue indefinitely until the bolus enters the stomach. The process of
peristalsis is controlled by medulla oblongata.
WHAT THE LIVER DOES?
●
It regulates the composition of blood, including the amounts of sugar
(glucose), protein, and fat that enter the bloodstream.
●
It removes bilirubin, ammonia, and other toxins from the blood.
●
It processes most of the nutrients absorbed by the intestines during
digestion and converts those nutrients into forms that can be used by the body.
●
The liver also stores some nutrients, such as vitamin A, iron, and other
minerals.
●
It produces cholesterol and certain important proteins, such as albumin.
●
It produces clotting factors, chemicals needed to help blood clot.
●
It breaks down (metabolizes) alcohol and many drugs.
WHAT THE GALL BLADDER DOES?
❖ Store
bile and release the bile to the duodenum for digestion of fats.
WHAT THE PANCREAS DOES?
I keep thinking, where was the food I just ate had gone
missing in my stomach (except the stool)?
Our foods participate in a process called
absorption. The thinnest product of digestion will be absorbed by villi
(structure in small intestine) into either blood vessel or lymph duct depend on
the type of product.
There is also a process called reabsorption.
This process only applied on water, electrolyte and bile acid.
#did
you know, normally, we do not feel the intestine's movements, but, if we eat too
much, we can experience a painful sensation and, if we get a food poisoning, we
will suffer of violent spasms and pain.
Why do we still need to defecate if the food is important
to our body? Was that not a waste?
#
actually, it’s
important to educate ourselves about defecation so that we can acquired some
knowledge on what’s weird, what’s normal, what’s healthy,
what’s not. That’s because your bathroom behavior can be an important clue to
your overall health. You can reveal signs of infections, digestive problems,
and even early signs of cancer.
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