Structure of the Pancreas
The pancreas is an elongated organ that lies behind and below the stomach. This mixed gland contains both exocrine and endocrine tissues. The predominant exocrine part consists of grape-like clusters of secretory cells that form sacs known as acini, which connect to ducts that eventually empty into the the first portion of the intestine called duodenum. The smaller part of the gland consists of isolated islands of endocrine tissue known as islets of Langerhans which are dispersed throughout the pancreas. Hormones Secreted by the Pancreas
The most important hormones secreted by the pancreas are insulin and glucagon. Both play a role in proper metabolism of sugars and starches in the body. Insulin promotes the movement of glucose and other nutrients out of the blood and into cells. When blood glucose rises, insulin, released from the beta cells causes glucose to enter body cells to be used for energy. Also, it sometimes stimulates conversion of glucose to glycogen in the liver. Another pancreatic hormone, glucagon, promotes the movement of glucose into the blood when glucose levels are below normal. It causes the breakdown of stored liver glycogen to glucose, so that the sugar content of blood leaving the liver rises.
Insulin is a hormone central to regulating carbohydrate and fat metabolism in the body. Insulin causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, storing it as glycogen in the liver and muscle. Insulin stops the use of fat as an energy source by inhibiting the release of glucagon. With the exception of the metabolic disorder diabetes mellitus and Metabolic syndrome, insulin is provided within the body in a constant proportion to remove excess glucose from the blood, which otherwise would be toxic. When blood glucose levels fall below a certain level, the body begins to use fat as an energy source through glycogenolysis, for example, by transfer of lipids from...