explain the mechanism of digestion in humans
Answers
Human Digestive System :-
The nutrition of human beings [ or man] takes place through human digestive system.The human digestive system consists of the alimentary canal and its associated glands.The various organs of the human digestive system are : Mouth , oesophagus , stomach , small intestine , large intestine .The glands associated with the human digestive system are : salivary glands, liver and pancreas.
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Process :-
The mouth cavity [ buccal cavity ] contains teeth , tongue and salivary glands.The teeth cuts the food into small pieces , chew and grind it .The salivary glands in our mouth produce saliva , which makes the food soft , so that it can be swallowed easily.Human saliva contains an enzyme called salivary amylase , that digests the starch present in the food into sugar.
The partially digested food in the mouth is swallowed by the tongue and goes down the food pope called oesophagus. The oesophagus carries food to the stomach.
The peristaltic [ contraction and expansion ] movement of food pipe allows the food to pass into the stomach.
The stomach is a J shaped organ.The stomach contains glands , which produce gastric juices,This gastric juice contains Hydrochloric acid, pepsin[enzyme] and mucus.
HCl makes the medium acidic , for the pepsin enzyme to act on the food and break down protein present in the food.HCl also kills microbes that my enter along with the food.Mucus protects the inner lining of stomach from the action of HCl.
From the stomach the partially digested food enters small intestine . Small intestine is the place where complete digestion of food takes place.
The small intestine receives secretions from two glands: liver and pancreas
Liver secretes bile juice, stored in gall bladder.Bile is alkaline in nature , and contains bile salts which helps to emulsify or break the fats present in the food.Bile juice makes the acidic food alkaline so that the pancreatic enzymes can act on it , and also the bile salts breaks the large globules of fat into small globules .
Pancreas secretes pancreatic juice , which contains enzymes like trypsin [ protein digestion] , lipase [ fat digestion ] and pancreatic amylase [breaks down starch]
The walls of small intestine secretes intestinal juice.This juice contains enzymes which complete the digestion of complex carbohydrates into glucose, proteins into amino acids, and fats into fatty acids and glycerol.
The inner surface of small intestine contains small finger like projections called villi , which increases surface area for absorption , and is richly supplied with blood vessels.
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