Diabetes complications

What are the islets of Langerhans and what are they for?

In the 19th century, a young scientist from Germany discovered heterogeneity of pancreatic tissue. Cells that differed from the main mass were located in small clusters, islets. Groups of cells were later called the pathologist's name - the islets of Langerhans (OL).

Their share in the total tissue volume is no more than 1-2%; however, this small part of the gland performs its function, which is different from the digestive one.

Destination Islets of Langerhans

The main part of the cells of the pancreas (pancreas) produces enzymes that promote digestion. The function of island clusters is different - they synthesize hormones, so they are referred to the endocrine system.

Thus, the pancreas is part of the two main systems of the body - the digestive and endocrine. The islands are microorganisms that produce 5 types of hormones.

Most of the pancreatic groups are located in the caudal portion of the pancreas, although chaotic, mosaic inclusions capture the entire exocrine tissue.

OLs are responsible for regulating carbohydrate metabolism and support the work of other endocrine organs.

Histological structure

Each island is an independently functioning element. Together they make up a complex archipelago, which is composed of individual cells and larger formations. Their sizes vary considerably - from one endocrine cell to a mature, large island (> 100 microns).

In pancreatic groups, a hierarchy of cell locations is built, there are 5 types of them, all of them fulfill their role. Each islet is surrounded by connective tissue, has lobules where the capillaries are located.

In the center there are groups of beta cells, along the edges of the formations - alpha and delta cells. The larger islet size, the more peripheral cells in it.

The islands do not have ducts, the hormones produced are excreted by the capillary system.

Cell types

Different groups of cells produce their own type of hormone, regulating digestion, lipid and carbohydrate metabolism.

  1. Alpha cells. This group of OL is located on the edge of the islets, their volume is 15-20% of the total size. They are the synthesis of glucagon - a hormone that regulates the amount of glucose in the blood.
  2. Beta cells. They are grouped in the center of the islets and make up most of their volume, 60–80%. They synthesize insulin, about 2 mg per day.
  3. Delta cells. They are responsible for the production of somatostatin, from 3 to 10%.
  4. Epsilon cells. The amount of the total mass of not more than 1%. Their product is ghrelin.
  5. PP cells. The hormone pancreatic polypeptide is produced by this part of OL. Make up to 5% of the islets.
With the passage of life, the proportion of the endocrine component of the pancreas decreases - from 6% in the first months of life to 1-2% by the age of 50.

Hormonal activity

The hormonal role of the pancreas is large.

Synthesized in small islands, the active substances are delivered to the organs by the bloodstream and regulate the metabolism of carbohydrates:

  1. The main objective of insulin is to minimize blood sugar levels. It increases the absorption of glucose by the cell membranes, accelerates its oxidation, and helps preserve it in the form of glycogen. Impaired hormone synthesis leads to the development of type 1 diabetes. At the same time, blood tests show the presence of antibodies to veta cells. Type 2 diabetes develops if insulin sensitivity to tissues decreases.
  2. Glucagon performs the opposite function - it increases the level of sugar, regulates the production of glucose in the liver, accelerates the breakdown of lipids. Two hormones, complementing each other's actions, harmonize the content of glucose - a substance that provides the body with vital activity at the cellular level.
  3. Somatostatin slows down the action of many hormones. When this happens, there is a decrease in the rate of absorption of sugar from food, a decrease in the synthesis of digestive enzymes, a decrease in the amount of glucagon.
  4. Pancreatic polypeptide reduces the amount of enzymes, slows the release of bile and bilirubin. It is believed that it stops the consumption of digestive enzymes, saving them until the next meal.
  5. Ghrelin is considered a hormone of hunger or satiety. Its production gives a signal to the body about the feeling of hunger.

The amount of hormones produced depends on the glucose received from food and the rate of its oxidation. As its amount increases, insulin production increases. The synthesis is started at a concentration of 5.5 mmol / l in plasma.

Not only food can provoke insulin production. In a healthy person, the maximum concentration is noted in the period of strong physical stress, stress.

The endocrine part of the pancreas produces hormones that have a decisive effect on the entire body. Pathological changes of the OL can disrupt the work of all organs.

Video about insulin tasks in the human body:

The defeat of the endocrine pancreas and its treatment

The cause of NL damage can be genetic predisposition, infections and poisoning, inflammatory diseases, immune problems.

As a result, termination or significant reduction in hormone production by different islet cells occurs.

As a result, it may develop:

  1. DM 1 type. Characterized by the absence or deficiency of insulin.
  2. Type 2 diabetes. Determined by the inability of the body to use the hormone produced.
  3. Gestational diabetes develops during pregnancy.
  4. Other types of diabetes mellitus (MODY).
  5. Neuroendocrine tumors.

The basic principles of the treatment of type 1 diabetes are the introduction of insulin into the body, the production of which is impaired or reduced. Apply two types of insulin - fast and long-acting. The latter type mimics the production of the hormone PZH.

Type 2 diabetes requires strict adherence to a diet, moderate exercise, and taking medications that help burn sugar.

Worldwide, there is an increase in the incidence of diabetes, it is already called the plague of the 21st century. Therefore, medical research centers are looking for ways to combat diseases of the islets of Langerhans.

The processes in the pancreas develop rapidly and lead to the death of the islets, which must synthesize hormones.

In recent years, it became known:

  • stem cells transplanted to the pancreatic tissue are well established and are able to further produce a hormone, as they begin to work like beta cells;
  • OLs produce more hormones if you remove some of the glandular tissue of the pancreas.

This allows patients to abandon constant medication, a strict diet and return to a normal lifestyle. The problem is the immune system, which can reject the implanted cells.

Another possible treatment option is to transplant a portion of the islet tissue from the donor. This method replaces the installation of artificial PZh or its full transplant from a donor. At the same time, it is possible to stop the progression of the disease and normalize blood glucose.

Successful operations were carried out, after which patients with type 1 diabetes eliminated the need for insulin administration. The organ has restored the beta cell population, and its own insulin synthesis has resumed. Immunosuppressive therapy was performed after surgery to prevent rejection.

Video material on glucose functions and diabetes:

Medical institutes are working to study the possibility of a pancreatic transplant from a pig. The first remedies for the treatment of diabetes mellitus just used part of the pancreas of pigs.

Scientists agree that research is needed on the specific features of the structure and operation of the islets of Langerhans because of the large number of important functions that hormones synthesize in them.

Constant intake of artificial hormones does not help to overcome the disease and worsens the patient’s quality of life. The defeat of this small part of the pancreas causes deep disruption of the entire body, so research continues.

Watch the video: Islets of Langerhans (September 2019).