Principles of Biochemistry

9.1.4.3 Hormones Secreted by Pancreas

The hormones secreted by the islets of langerhans of pancreas are polypeptides function to maintain energy homeostasis. Thay are glucagon, made by the α cells; insulin, made by the β  cells; and somatostatin made by the δ cells. All these hormones have pronounced effects on metabolism, particularly on that of carbohydrates.

Insulin, which is secreted in response to high blood glucose levels, functions to stimulate muscle, liver, and adipose cells to store glucose for later use by the synthesizing glycogen, protein, and fat.

Glucagon, which is secreted in response to low blood glucose, has the opposite effect. It stimulates liver to release glucose through the breakdown of glycogen and the synthesis of glucose from noncarbohydrate precursors. It also stimulates adipose tissue to release fatty acids through lipolysis.

Somatostatin inhibits the release of insulin and gucagon from their islet cells.