How do we digest food?
The human body requires a constant supply of food in
order to carry out its numerous activities. The food we consume performs two
main functions in our body. First, it supplies proteins for the growth of the
body and second, it supplies energy to the tissues for the day to day work.
The Human Digestive System
The process of digestion is very complex and elaborate.
Digestion begins at the mouth. When we chew food, the saliva produced in the
mouth moistens it. The saliva contains a substance called ptyalin, which
converts the starch of the food into simple sugar. This is the first stage of
digestion. Therefore we should swallow the food only after chewing it properly.
After that, the food material passes through the esophagus
to the stomach where the gastric juices get mixed with it. The walls of the
stomach secret juices containing an enzyme called pepsin and hydrochloric acid.
Pepsin breaks down the molecules of proteins into peptones.
From stomach, the food then enters the small intestine,
where it mixes with three other digestive juices- bile, pancreatic juice and
intestinal juice. The liver produces bile. Its main function is to digest the
fats. The pancreatic juice is basic in nature and neutralizes the acids. It
also digests the proteins. The intestinal juice converts sugar into glucose.
Here, many enzymes also mix with the food. The digestion of food mainly takes
place here. The digested food is them absorbed by the blood vessels present in
the wall of small intestine. The remaining waste of the food now goes to the
large intestine and is finally excreted out of the body as faeces through the
anus.
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