The small intestine is the longest part (about 5 to 6 m) of the alimentary canal fitted into a compact space in the belly by extensive coiling. The length of the small intestine differs in various animals depending on the food they eat. Carbohydrates, fats and proteins are fully digested in the small intestine. Since this action takes place only in alkaline conditions, the acidic food received from the stomach has to be first made alkaline. Liver, the largest gland in the body secretes bile juice which is stored in the gall bladder. Whenever food enters the small intestine the gall bladder releases bile into it through a duct. Bile makes the food alkaline and breaks the large fat globules into smaller ones, this increases the enzyme action.
Pancreas secretes pancreatic juice. It has digestive enzymes like trypsin (to digest proteins), lipase (to break down fats) and pancreatic amylase (to digest carbohydrates). The bile and the pancreatic juice enter the small intestine through a common duct. Various intestinal juices are also secreted by the walls of the small intestine to complete the digestion process of converting proteins to amino acids, complex carbohydrates to glucose, and fats into fatty acids. The digested food is absorbed by the walls of the small intestine having numerous finger like projections called villi which are richly supplied by blood capillaries. The absorbed food is taken to each and every cell of the body where it is utilized for obtaining energy. Unused glucose is stored in the liver in the form of glycogen. The unabsorbed food is sent to the large intestine.
Pancreas secretes pancreatic juice. It has digestive enzymes like trypsin (to digest proteins), lipase (to break down fats) and pancreatic amylase (to digest carbohydrates). The bile and the pancreatic juice enter the small intestine through a common duct. Various intestinal juices are also secreted by the walls of the small intestine to complete the digestion process of converting proteins to amino acids, complex carbohydrates to glucose, and fats into fatty acids. The digested food is absorbed by the walls of the small intestine having numerous finger like projections called villi which are richly supplied by blood capillaries. The absorbed food is taken to each and every cell of the body where it is utilized for obtaining energy. Unused glucose is stored in the liver in the form of glycogen. The unabsorbed food is sent to the large intestine.
