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The Process Of Food Digestion - A Fascinating
Story
How food gets converted into nutrients
When food is solid we chew it. We swallow it if it is liquid.
Then it goes down our throats. It is interesting to learn what happens to food in entire digestive track and how
our food habits influence our health, fitness and wellness.
Mouth
process:
When we chew our food in
mouth it gets broken into small pieces and gets mixed with saliva.
Saliva is a colorless watery liquid which is always present in our
mouth. It contains enzymes which digest food. These enzymes in saliva convert insoluble starches
into water-soluble substances.
Actually this is the process of digestion. Enzymes convert many complex food
substances into simpler substances which then can be absorbed by the body and used for its needs. These
enzymes are made by different organs / glands. What finally remains after processing of the food in the digestive
track is not useful for the body & is thrown out as stools or faeces.
When we smell food, our mouth waters. Saliva starts flowing down from the three pairs
of salivary glands -- one pair below & in front of each ear, another pair at the back of the lower jaw &
the third pair underneath the tongue.
We normally produce about 8 to 10 cups
of saliva in a day, in our mouth.
The enzyme in this saliva breaks down carbohydrate into simpler soluble forms of
sugar.
The more we break our food by munching, the better. Saliva
can then act faster on the food. Thorough chewing helps digestion process. ( It is said, every mouthful of food
should be chewed 32 times, once for each tooth
).
Food then passes down our throat through food
pipe. The small flexible lid in our food pipe, called epiglottis, closes automatically when we gulp down
our food. It prevents food from going down the wrong passage which is wind pipe, lying alongside.
Stomach Process:
Stomach is an important bag shaped organ. It constantly contracts and relaxes and churns the food
inside. Inside lining of stomach secretes many enzymes.
These enzymes help to breakdown proteins in order to allow
body to absorb nutrients. These nutrients are then used up by body for body repair or body growth or as a fuel
(energy).
Large number of glands are present inside lining of the
stomach. One of the enzymes, called Renin, converts protein from milk, into soft curd. Another enzyme, called
Pepsin, breaks down the long protein chains into smaller units called Peptones which are soluble in
water.
Stomach also makes a large amount of hydrochloric acid. This is the same acid which
we see in the chemical laboratory. This acid does many jobs as follows:
1) It weakens the proteins by loosening some of
their links.
2) It dissolves minerals from various foods we
eat
3) It kills bacteria which enter our stomach
with the food we eat.
Food stays in the mouth for a few minutes but stays in the stomach for hours. maximum
secretion of Renin, Pepsin & hydrochloric acid takes place about two hours after eating a meal. Food digestion
at this time goes on very actively.
Digestion in the stomach is basically
breaking down of proteins into simpler peptone units with the help of two
enzymes and hydrochloric acid.
Outflow valve of stomach which remains closed most of the time during the day, opens
up occasionally & allows very small amount of semi-digested / digested food to proceed further into small
intestine. This valve opens and closes automatically. It allows partly digested semi-fluid, pasty food to pass
through to small intestine.
Small intestine
process:
Small intestine is a long tube which
further processes the semi-digested food which comes from stomach.
Top part of small intestine is called duodenum and is about 25 cms long. There are main three juices which digest food in
the small intestines. Bile juice, a bitter substance comes from
liver.
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