Islet of Langerhans pancreas. Islets of Langerhans: Cell Types, Features and Structure
The pancreas is considered one of the vital organs. She is not only actively involved in the process of digesting food, but also has endocrine functions. Internal secretion is carried out thanks to special cells located in the tail of this anatomical formation. The place where pancreatic hormones are produced is called the islet of Langerhans. This anatomical formation has a great functional value. Thanks to him, provides carbohydrate metabolism.
What is the island of Langerhans: destination
Endocrine cells are located throughout the body. One of the places of their accumulation is the pancreas. The islets of Langerhans are localized in the tail part of the organ. They are cell clusters that produce biologically active substances - hormones.The importance of the islets of Langerhans is enormous. It consists in the production of the normal amount of hormones necessary for metabolic processes. The islets of Langerhans of the pancreas have the following functions:
- Glycemia control.
- Regulation of enzyme activity.
- Participation in fat metabolism.
Due to the normal operation of the insular apparatus, conditions such as diabetes and hypoglycemia do not develop. Cell damage occurs in acute and chronic inflammation - pancreatitis.
Histological structure of the islets
The islet of Langerhans was discovered in the 19th century. It represents the concentration of endocrine elements. In children, these educations occupy about 6% of the total area of the organ. By adulthood, the endocrine portion is reduced and is only 2%. The tail parenchyma contains about a million islets of Langerhans. They have their own abundant blood supply and innervation. Each islet consists of lobules that covers connective tissue. In addition, it is located outside the endocrine formations. Cells inside the islands are arranged in a mosaic.The activity of endocrine clusters provide the wandering and sympathetic nerves. In the center of the lobule are insular cells. They reduce blood glucose levels. In the peripheral part of the lobules are alpha and delta cells. The first produce a contra-insulin hormone - glucagon. The latter are necessary for the regulation of endocrine and exocrine activity.
What are the cells of the islets of Langerhans?
In the islets of Langerhans produced several types of cells. All of them are involved in the release of biologically active substances - peptides and hormones. Most of the islets of Langerhans are represented by beta cells. They are located in the center of each lobule. These cells are very important because they produce insulin.
Second in importance are the alpha cells of the pancreas. They occupy a quarter of the area of the island. Alpha cells are required for the production of glucagon. This hormone is an insulin antagonist.
In the peripheral part of the islets of Langerhans, PP and delta cells are produced. The number of the first is about 1/20 part. The function of these formations is pancreatic polypeptide production.Delta cells are needed to produce somatostatin. This substance is involved in the regulation of carbohydrate metabolism.
Islet cells are difficult to regenerate. Therefore, if these structures are damaged, it is often impossible to restore their function.
Hormonal activity of the islets of Langerhans
Despite the fact that the islet of Langerhans is small and occupies only a small part of the pancreas, the value of this fragment is great. In it occurs the formation of the most important hormones involved in metabolic processes. The islets of Langerhans produce insulin, glucagon, somatostatin and pancreatic polypeptide.
The first 2 hormones are essential for vital activity. Insulin triggers the breakdown of glucose into smaller molecular compounds. As a result, the blood sugar level decreases. In addition, insulin is involved in the metabolism of fats. Thanks to the actions of this hormone, glycogen accumulates in the liver and muscle tissue. Insulin has an anabolic effect on the general metabolism, that is, it accelerates all processes.
Glucagon has the opposite effect.This hormone is produced in smaller amounts compared to insulin. He is involved in gluconeogenesis. Sugar is needed in the body, as it is a source of energy.
Somatostatin regulates the production of digestive enzymes and hormones. Under the influence of this substance decreases the production of glucagon and insulin. There are very few PP cells in the islets of Langerhans, however, a pancreatic polypeptide is necessary for the organism. It is involved in the regulation of the secretion of digestive glands (liver, stomach). With a lack of hormonal activity develop serious illness.
The defeat of the endocrine pancreas
Disruption of islet cell activity can occur for a variety of reasons. Often, the failure of these structures refers to congenital anomalies (genetic pathologies). Acquired damage to the islets of Langerhans develops due to viral and bacterial infections, chronic alcohol intoxication, and neurological diseases.
Insulin deficiency leads to type 1 diabetes. This disease occurs in children and young.An increase in blood glucose leads to vascular and nerve damage. With a deficit of other islet cells, a hypoglycemic state develops, an increased production of digestive juices. Enhanced hormone production occurs with benign tumors of the tail of the pancreas.
Langerhans Island Transplant
A method of treating diabetes is insulin replacement therapy. In recent years, alternative methods have been developed. These include the introduction of an artificial pancreas and islet cell transplantation. In practice, it turned out that hormone-producing structures take root in the new organism. At the same time, carbohydrate metabolism can fully recover. Transplantation of the islets of Langerhans has not yet been widely used in practice.