Islets of pancreatic Langergans
islets of Langerhans of the pancreas - a cluster of endocrine cells that produce hormones.
Groups of such cells were discovered as early as 1869 by the scientist Paul Langerhans, after whom they were named. Cells of islets are concentrated mainly in the tail of the pancreas and make up 2% of the body weight. In total there are about 1 million islets in the parenchyma.
It was revealed that in newborns the islets occupy 6% of the total body weight. As the body grows, the proportion of structures with endocrine activity decreases. By the age of 50, only 1-2% of them remain. During the day, the islets of Langerhans secrete 2 mg of insulin. From what cells are islands?
The islets of Langerhans have different, morphologically and functionally, cells.
Endocrine pancreatic segment includes :
- alpha cells - produce glucagon, which is an antagonist of insulin enhances glucose level in blood plasma. Occupy 20% of the weight of the remaining cells.
- Beta cells - synthesize insulin and amelin. They constitute 80% of the mass of the islet.
- Delta cells - provide the production of somatostatin, which can inhibit the secretion of other glands. These cells are from 3 to 10% of the total mass.
- PP cells - produce a pancreatic polypeptide. He is responsible for increasing gastric secretion and suppressing the function of the pancreas.
- Epsilon cells - isolate ghrelin, which is responsible for the occurrence of a feeling of hunger.
Why do we need islands and how are they arranged?
The islets of Langerhans are responsible for maintaining the balance of carbohydrates in the body and the work of other endocrine organs. They have abundant blood supply, are innervated by wandering and sympathetic nerves. Among the islets are neuro-insular complexes. Ontogenetically, the islet cells are formed from epithelial tissue.
Island has a complex structure and each of them is a full functionally active form. Its structure facilitates the exchange of biologically active substances between other glands for the simultaneous secretion of insulin. The cells of the islets are arranged in the form of a mosaic, that is, they are intermixed. The exocrine structure of the pancreas can be represented by clusters of several cells and large islets.
It is known that a mature islet in the parenchyma has an orderly organization. It is surrounded by a connective tissue, has lobules, and inside it there are blood capillaries. The center of the lobule is filled with beta cells, and on the periphery the alpha and delta cells are located. We can say that the structure of an island is directly related to its size.
What is the endocrine function of the islets and why are antibodies formed against them?
The interaction of islet cells forms a feedback mechanism. Cells influence located near:
- Insulin has an activating effect on beta cells and alpha inhibits cells.
- Glucagon activates alpha cells, which in turn affect delta cells.
- Somatostatin suppresses the work of alpha and beta cells.
case of violation of the immune mechanisms of antibody formation against beta-cells that destroy them and lead to the development of diabetes. What is the purpose of the islet transplantation? Why
?
Islet transplantation is a worthy alternative to a pancreas transplant or an artificial organ installation. Such intervention gives a chance for patients with diabetes to restore the structure of beta-cells. Clinical studies have been conducted in which island patients with type 1 diabetes were transplanted with islet cells from donors. As a result of the tests, it was revealed that such intervention leads to the restoration of regulation of the level of carbohydrates. Patients with diabetes mellitus undergoes powerful immunosuppressive therapy to prevent rejection of donor tissues.
An alternative source of material for the recovery of islets are stem cells. They can be relevant, as the reserves of donor cells are limited. Regenerative medicine is developing rapidly, offering new methods of treatment in many areas. It is important to restore the tolerance of the immune system, since the new transplanted cells will also be destroyed after a certain period of time.
Has the prospect of xenotransplantation - a pancreas transplant from a pig. Before the discovery of insulin, extracts from pork pancreas were used to treat diabetes mellitus. It is known that human insulin and pork differ only in one amino acid.
The study of the structure and function of the islets of Langerhans has great prospects, as diabetes develops due to the damage to their structure.
