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What are Digestive Glands and explain its role in Digestion? NIRMALA AGARWAL The essential functions of Digestive Glands are:Salivary Glands: In man there are three pairs of salivary glands (sub maxillary, sublingual, and parotid) which secrete saliva. Saliva contains an enzyme called salivary amylase which breaks down starch (complex substance) of the food into maltose (a simpler sugar). Thus, in the mouth cavity saliva moistens the masticated food and starts digestion of carbohydrate. Gastric Gland: The gastric glands secrete hydrochloric acid and gastric juice which help in digestion of food. The enzyme pepsin present in the gastric juice acts on the proteins of the food and breaks them into smaller units called peptones and proteoses. The food then passes into the small intestine. Liver: It is the largest gland of the body. It weighs 1.5 kg in man. Liver performs many functions. As far as digestion is concerned, it secretes a fluid called bile. Bile juice produced by the liver is stored in the gall bladder. Gall stones which are found in the gall bladder of about 8% of the people are chiefly the concretions (depositions) of cholesterol, bile pigments and calcium salts. Bile is yellowish greenish, alkaline fluid. Bile emulsifies fats which help in breaking them into small globules. In this way, fat globules are easily exposed to the action of fat-hydrolyzing, enzymes. The acidic food coming from the stomach becomes alkaline, when it is mixed with the bile. It is an extremely important step which ensures further digestion of the food. The digestive enzymes that are brought in the duodenum and ileum can catalyse the breakdown of food only in alkaline medium. Pancreas: It is the second largest gland of the body. It lies in the fold of duodenum. It is yellowish. It secretes pancreatic juice. Pancreatic duct pours pancreatic juice into the duodenum. Pancreatic juice contains a number of digestive enzymes. These include trypsin and chymotrypsin for the breakdown of proteins; amylase for the splitting of polysaccharides; lipase for the breakdown of fats and nuclease for the breakdown of nucleic acids. These enzymes catalyse the breakdown of different constituents of food but not sufficiently enough to break all of them into their units. Intestinal Glands: The final step of digestion takes place in the ileum. There are numerous smaller glands occupying the walls of the small intestinal tract. These glands secrete what is termed intestinal juice or succus entericus. The intestinal glands are in the form of sunken pits or crypts which are interspersed among the finger-like villi. The digestive enzymes in the intestinal juice include carboxypeptidase and aminopeptidase which break small peptides into amino acids; sucrose, maltase and lactase which brak disaccharides into respective monosaccharides; lipase which breaks lipids into fatty acid and glycerol; and nuclease which breaks nucleic acids into nucleotides.