Pancreas is a mixed gland containing both exocrine and endocrine tissues. The exocrine portion secretes digestive juice into the pancreatic duct whereas the endocrine tissue secretes hormones into the blood.So the pancreas function means the functions of the pancreatic hormones.
Insulin and glucagon, the chief hormones of pancreas, regulate the metabolism of carbohydrate, fat and protein. These two hormones are functionally opposite to each other. Somatostatin on the other hand, regulates the secretion of other hormones and gastrointestinal functions. The functions of the three pancreatic hormones are discussed below.
Pancreas Function of Glucagon
It is a catabolic hormone i.e., it stimulates catabolism of carbohydrate, prqjein and fat, thereby depleting the reserve food stores of the body. It has the following actions.
The chief function of glucagon is to increase the blood sugar (glucose) level. Hence, it is also called hyperglycemic factor of pancreas. Glucagon raises blood sugar level by stimulating glycogenolysis (breakdown of glycogen to glucose) and neoglucogenesis (formation of glucose from non-carbohydrates like protein and fat) in liver. When blood sugar level is low the secretion of glucagon is stimulated and as a pancreas function this hormone helps to raise the blood sugar level to normal.
It increases the catabolism of amino acids in liver and urinary excretion of nitrogen, thereby causing a negetive nitrogen balance as the pancreas function.
Glucagon activates the enzyme lipase present in liver and adipose tissue as a result of which lipids are broken down and free fatty acid level of blood is increased.
Glucagon increases heat production (or BMR) in the body because of its catabolic effects.
Pancreas Functions of Insulin
Insulin is essentially an anabolic hormone because it helps to increase the storage of food in the body. It has the following actions in the body.
The chief function of insulin is to reduce the blood sugar (glucose) level. It is the only hormone that has a blood sugar lowering effect; hence insulin is also called hypoglycemic factor. The hypoglycemic effect of insulin is achieved in the following ways:—
i) It increases the permeability of different tissues to glucose so as to facilitate convey of glucose from blood to tissues.
ii) It helps in utilization of glucose in the cells by stimulating glycogenesis (formation of glycogen from glucose), lipogenesis (conversion glucose to fat) and oxidation of glucose for acquiescent energy.
iii) It inhibits formation of glucose through glycogenolysis and neoglucogenesis in liver and its entry into the blood as the pancreas function.
Insulin also increases the permeability of tissues to amino acids like that of glucose and helps in the entry of amino acids from blood to tissues. It stimulates synthesis of proteins from amino acids entering into the tissues. In addition, insulin prevents catabolism of tissue proteins.
It stimulates lipogenesis and reduces lipolysis in tissues.
Insulin helps in growth of the body by virtue of its protein anabolic effects because growth is not possible without protein synthesis. Insulin is required for the growth promoting action of STH.
Secretion of insulin from pancreas is stimulated when the blood sugar level is raised that is during absorption of food after meals. Thus, the absorbed glucose is well utilized and blood glucose level is brought back to normal; otherwise, glucose would escape through urine.
Pancreas Functions of Somatostatin
Somatostatin secreted from 8-cells of pancreas inhibits the secretion of insulin and glucagon from the pancreatic islets in a paracriun fashion i.e., it acts locally on the circulating blood. It may also directly inhibit the secretion of both bicarbonate and enzymes in pancreatic juice. The pancreatic Somatostatin is also released into the circulating blood which inhibits secretion of gastrin, secretin, CCK-PZ, VIP, GIF, motilin etc., from the gastrointestinal mucosa and thereby the secretion and motility of the gastrointestinal tract.