Endocrine part of the pancreas

The pancreas consists of the exocrine and endocrine parts. The endocrine part of the pancreas (pars endocrina pancreatis) is represented by groups of epithelial cells forming a peculiar form of pancreatic islets (islets of Langerhans, insulae pancreaticae) separated from the exocrine part of the gland by thin connective tissue layers. Pancreatic islets are found in all parts of the pancreas, but most of all in the tail region. The size of the islands varies from 0.1 to 0.3 mm, and the total mass does not exceed 1 / wu of the pancreas mass. The total number of islands from 1 to 2 million islets consist of endocrine cells. There are five main types of these cells. The majority (60-80%) of cells are beta cells, located mainly in the inner parts of the islets and secreting insulin; alpha-cells - 10-30%. They produce glucagon. About 10% are D-cells that secrete somatostatin. A few PP-cells that occupy the periphery of the islets synthesize the pancreatic polypeptide.

Insulin promotes the conversion of glucose into glycogen, enhances the metabolism of carbohydrates in the muscles. Glucagon enhances the formation of triglycerides from fatty acids, stimulates their oxidation in hepatocytes. With an increase in the concentration of glucose in the blood flowing through the pancreas, the secretion of insulin increases and the blood glucose level decreases. Somatostatin depresses the production of the growth hormone by the pituitary gland, as well as the isolation of insulin and glucagon by A- and B-cells. Pancreatic polypeptides stimulate the secretion of gastric and pancreatic juice by pancreatic exocrine cells.

Pancreatic islets develop from the same epithelial rudiment of the primary intestine as the exocrine part of the pancreas. They are abundantly supplied with blood from the wide blood capillaries surrounding the islets and penetrating between the cells.