HOW DIGESTION TAKES PLACE INSIDE THE BODY?
When the food enters into the body, It becomes wet by the contact of water and saliva. Saliva contain an enzyme called salivary amylase which breaks down the complex starch into simple sugar. Then it moves into the food pipe or Oesophagus. Rhythmic contraction and relaxation apply force to move food forward. These rhythmic contraction and relaxation of foodpipe is called peristaltic Movement. Opposite movement of this, known as Anti-peristaltic Movement occurs sometimes inside our body during vomiting. Anyway, Then the food moves into the stomach. Gastric glands are present in the walls of the stomach which release hydrochloric acid, protein digesting enzyme called pepsin and mucus. The hydrochloric acid creates an acidic medium of food which facilitates the action of enzyme pepsin. The mucus protects the inner lining of the stomach from the hydrochloric acid. Then the food moved into the small intestine. The exit of food is regulated by the sphincter which allows small amount of food to move into the small intestine. Small intestine is a site where complete digestion takes place. It receives the juices secreted by liver and pancreas. The food is acidic which should be turned into alkaline for better action of pancreatic juice. Bile salts break down large globules of fats into small globules, increasing the efficiency of enzyme action. Pancreatic juice contain an enzyme called trypsin for digesting proteins and lipase for breaking down emulsified fats. Then the small intestine secretes intestinal juices which finally converts the protein into amino acid and complex carbohydrates into glucose and fats into fatty acid and glycerol. The digested food is absorbed in the walls of small intestine which is comprised of numerous finger-like projections called villi. It increases the surface area for absorbtion. It is then supplied with blood vessels which take the absorbed food to every cells of the body. The undigested food is taken up by the large intestine which absorb more water from the waste materials. Then the waste by-products are removed from the body via Anus. The exit of waste materials is regulated by the Anal Sphincter.
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