What hormone is secreted by the islets of Langerhans. Islets of Langerhans: structure and role for the pancreas

Pancreas- the second largest iron, its weight is 60-100 g, length is 15-22 cm.

The endocrine activity of the pancreas is carried out by the islets of Langerhans, which consist of different types of cells. About 60% of the islet apparatus of the pancreas are β-cells. They produce a hormone insulin, which affects all types of metabolism, but primarily lowers glucose levels.

Table. Pancreatic hormones

Insulin(polypeptide) is the first protein produced synthetically outside the body in 1921 by Beilis and Bunty.

Insulin dramatically increases the permeability of the membrane of muscle and fat cells for glucose. As a result, the rate of glucose transfer into these cells increases approximately 20 times compared to the transfer of glucose into cells in the absence of insulin. In muscle cells, insulin promotes the synthesis of glycogen from glucose, and in fat cells, fat. Under the influence of insulin, the permeability for amino acids also increases, from which proteins are synthesized in cells.

Fig. Major hormones affecting blood glucose levels

Pancreatic second hormone glucagon- is secreted by the a-cells of the islets (approximately 20%). Glucagon by chemical nature polypeptide, and physiological effect of an insulin antagonist. Glucagon enhances the breakdown of glycogen in the liver and increases plasma glucose levels. Glucagon promotes the mobilization of fat from fat stores. A number of hormones act like glucagon: STH, glucocorticones, adrenaline, thyroxine.

Table. The main effects of insulin and glucagon

Exchange type	Insulin	Glucagon
Carbohydrate	Increases the permeability of cell membranes for glucose and its utilization (glycolysis) Stimulates glycogen synthesis Suppresses gluconeogenesis Reduces blood glucose levels	Stimulates glycogenolysis and gluconeogenesis Has a counterinsular effect Increases blood glucose levels
Protein	Stimulates anabolism	Stimulates catabolism
	Suppresses lipolysis Decreases the number of ketone bodies in the blood	Stimulates lipolysis The number of ketone bodies in the blood rises

The third hormone of the pancreas is somatostatin released by 5 cells (approximately 1-2%). Somatostatin inhibits the release of glucagon and the absorption of glucose in the intestine.

Hyper- and hypofunction of the pancreas

With hypofunction of the pancreas, diabetes. It is characterized by a number of symptoms, the occurrence of which is associated with an increase in blood sugar - hyperglycemia. Increased content glucose in the blood, and therefore in the glomerular filtrate, leads to the fact that the epithelium of the renal tubules does not completely reabsorb glucose, therefore it is excreted in the urine (glucosuria). There is a loss of sugar in the urine - sugar urination.

The amount of urine is increased (polyuria) from 3 to 12, and in rare cases up to 25 liters. This is due to the fact that unreabsorbed glucose increases the osmotic pressure of urine, which holds water in it. Water is not sufficiently absorbed by the tubules, and the amount of urine excreted by the kidneys is increased. Dehydration of the body makes diabetics thirsty, which leads to an abundant intake of water (about 10 liters). In connection with the excretion of glucose in the urine, the expenditure of proteins and fats as substances that ensure the energy metabolism of the body increases sharply.

The weakening of glucose oxidation leads to a violation of fat metabolism. The products of incomplete oxidation of fats are formed - ketone bodies, which leads to a shift in the blood to the acidic side - acidosis. Ketone accumulation and acidosis can cause a severe, life-threatening condition - diabetic coma, which proceeds with loss of consciousness, impaired breathing and blood circulation.

Pancreatic hyperfunction is a very rare condition. Excessive insulin in the blood causes a sharp decrease in sugar in it - hypoglycemia, which can lead to loss of consciousness - hypoglycemic coma. This is because the central nervous system is very sensitive to a lack of glucose. The introduction of glucose removes all these phenomena.

Regulation of pancreatic function. Insulin production is regulated by a negative feedback depending on the concentration of glucose in the blood plasma. Increased blood glucose increases insulin production; under conditions of hypoglycemia, the formation of insulin, on the contrary, is inhibited. Insulin production can increase when the vagus nerve is stimulated.

Pancreatic endocrine function

Pancreas(an adult weighs 70-80 g) has a mixed function. Acinous tissue of the gland produces digestive juice, which is excreted into the lumen duodenum... The endocrine function in the pancreas is performed by clusters (from 0.5 to 2 million) of cells of epithelial origin, called the islets of Langerhans (Pirogov - Langerhans) and accounting for 1-2% of its mass.

Paracrine regulation of cells of the islets of Langerhans

The islets contain several types of endocrine cells:

• a-cells (about 20%) that form glucagon;
• β-cells (65-80%) that synthesize insulin;
• δ-cells (2-8%) synthesizing somatostatin;
• PP cells (less than 1%) producing pancreatic polypeptide.

Young children have G cells that produce gastrin. The main hormones of the pancreas that regulate metabolic processes are insulin and glucagon.

Insulin- a polypeptide consisting of 2 chains (A-chain consists of 21 amino acid residues and a B-chain of 30 amino acid residues) linked by disulfide bridges. Insulin is transported by blood mainly in a free state and its content is 16-160 μU / ml (0.25-2.5 ng / ml). Per day (3 cells of an adult healthy person produce 35-50 U of insulin (approximately 0.6-1.2 U / kg body weight).

Table. Mechanisms of glucose transport into the cell

Type of fabric	Mechanism
Insulin dependent	For the transport of glucose in the cell membrane, the GLUT-4 transporter protein is required Under the influence of insulin, this protein moves from the cytoplasm to the plasma membrane and glucose enters the cell by facilitated diffusion Stimulation with insulin leads to an increase in the rate of glucose entry into the cell by 20-40 times; the transport of glucose in muscle and adipose tissues depends to the greatest extent on insulin
Insulin independent	The cell membrane contains various glucose transport proteins (GLUT-1, 2, 3, 5, 7), which are incorporated into the membrane independently of insulin With the help of these proteins, by facilitated diffusion, glucose is transported into the cell along a concentration gradient Insulin-independent tissues include: brain, gastrointestinal epithelium, endothelium, erythrocytes, lens, p-cells of the islets of Langerhans, renal medulla, seminal vesicles

Insulin secretion

Insulin secretion is divided into basal, which is pronounced, and stimulated by food.

Basal secretion ensures optimal levels of blood glucose and anabolic processes in the body during sleep and in the intervals between meals. It is about 1 U / h and it accounts for 30-50% of the daily secretion of insulin. Basal secretion significantly decreases with prolonged physical activity or fasting.

Food-stimulated secretion is an increase in basal insulin secretion caused by food intake. Its volume is 50-70% of the daily rate. This secretion ensures the maintenance of blood glucose levels in the presence of additional intake from the intestine, enables its efficient absorption and utilization by cells. The severity of secretion depends on the time of day, has a biphasic character. The amount of insulin secreted into the blood is approximately the same as the amount of carbohydrates taken and is 1-2.5 U of insulin for every 10-12 g of carbohydrates (in the morning 2-2.5 U, at lunchtime - 1-1.5 U, in the evening - about 1 U ). One of the reasons for this dependence of insulin secretion on the time of day is high level in the blood of contrainsular hormones (primarily cortisol) in the morning and its decrease in the evening.

Fig. Insulin secretion mechanism

The first (acute) phase of stimulated insulin secretion does not last long and is associated with exocytosis by β-cells of the hormone already accumulated between meals. It is due to the stimulating effect on β-cells not so much of glucose as of the hormones of the gastrointestinal tract - gastrin, enteroglucagon, glycentin, glucagon-like peptide 1, secreted into the blood during food intake and digestion. The second phase of insulin secretion is due to the stimulating action of insulin secretion on β-cells by glucose itself, the level of which in the blood rises as a result of its absorption. This action and the increased secretion of insulin continue until the glucose level reaches the normal level for the person, i.e. 3.33 - 5.55 mmol / L in venous blood and 4.44 - 6.67 mmol / L in capillary blood.

Insulin acts on target cells by stimulating 1-TMS membrane receptors with tyrosine kinase activity. The main target cells of insulin are hepatocytes of the liver, myocytes of skeletal muscles, adipocytes of adipose tissue. One of its most important effects is a decrease in the level of glucose in the blood, which insulin implements through an increase in the absorption of glucose from the blood by target cells. This is achieved by activating the work of transmembrane glucose transporters (GLUT4) inserted into the plasma membrane of target cells and increasing the rate of glucose transfer from blood to cells.

Insulin is metabolized by 80% in the liver, the rest in the kidneys and a small amount in muscle and fat cells. Its half-life from the blood is about 4 minutes.

The main effects of insulin

Insulin is an anabolic hormone and has a number of effects on target cells in various tissues. It has already been mentioned that one of its main effects - a decrease in the level of glucose in the blood is realized by increasing its absorption by target cells, accelerating the processes of glycolysis and oxidation of carbohydrates in them. A decrease in glucose levels is promoted by insulin stimulation of glycogen synthesis in the liver and muscles, suppression of gluconeogenesis and glycogenolysis in the liver. Insulin stimulates the absorption of amino acids by target cells, reduces catabolism and stimulates protein synthesis in cells. It also stimulates the conversion of glucose into fats, the accumulation of triacylglycerols in adipocytes of adipose tissue and suppresses lipolysis in them. Thus, insulin has a general anabolic effect, enhancing the synthesis of carbohydrates, fats, proteins and nucleic acids in target cells.

Insulin has a number of other effects on cells, which, depending on the rate of manifestation, are divided into three groups. Fast effects are realized in seconds after binding of the hormone to the receptor, for example, the absorption of glucose, amino acids, potassium by cells. Slow effects are deployed in minutes from the onset of the hormone action - inhibition of the activity of enzymes of protein catabolism, activation of protein synthesis. Delayed Effects insulin begins hours after it binds to receptors - DNA transcription, mRNA translation, acceleration of cell growth and multiplication.

Fig. Insulin mechanism of action

The main regulator of basal insulin secretion is glucose. An increase in its content in the blood to a level above 4.5 mmol / l is accompanied by an increase in insulin secretion by the following mechanism.

Glucose → facilitated diffusion with the participation of the GLUT2 transporter protein into the β-cell → glycolysis and accumulation of ATP → closure of ATP-sensitive potassium channels → delayed release, accumulation of K + ions in the cell and depolarization of its membrane → opening of voltage-gated calcium channels and the supply of Ca 2 ions + into the cell → accumulation of Ca2 + ions in the cytoplasm → increased insulin exocytosis. Insulin secretion is stimulated in the same manner by increasing blood levels of galactose, mannose, β-keto acid, arginine, leucine, alanine and lysine.

Fig. Regulation of insulin secretion

Hyperkalemia, sulfonylurea derivatives (medicines to treat diabetes mellitus type 2), blocking the potassium channels of the plasma membrane of β-cells, increase their secretory activity. Increase insulin secretion: gastrin, secretin, enteroglucagon, glycentin, glucagon-like peptide 1, cortisol, growth hormone, ACTH. An increase in insulin secretion by acetylcholine is observed upon activation parasympathetic department ANS.

Inhibition of insulin secretion is observed in hypoglycemia, under the influence of somatostatin, glucagon. Catecholamines, which are released when the SNS activity increases, have an inhibitory effect.

Glucagon - peptide (29 amino acid residues) formed by the a-cells of the islet apparatus of the pancreas. It is transported by blood in a free state, where its content is 40-150 pg / ml. It has its effects on target cells by stimulating 7-TMS receptors and increasing the level of cAMP in them. The half-life of the hormone is 5-10 minutes.

Counterinsular action of glucogone:

• Stimulates β-cells of the islets of Langerhans, increasing insulin secretion
• Activates liver insulinase
• Has antagonistic effects on metabolism

Diagram of a functional system that maintains an optimal blood glucose level for metabolism

Main effects of glucagon in the body

Glucagon is a catabolic hormone and insulin antagonist. In contrast to insulin, it increases blood glucose by enhancing glycogenolysis, suppressing glycolysis, and stimulating gluconeogenesis in hepatocytes. Glucagon activates lipolysis, causes an increased flow of fatty acids from the cytoplasm into mitochondria for their β-oxidation and the formation of ketone bodies. Glucagon stimulates protein catabolism in tissues and increases urea synthesis.

The secretion of glucagon increases with hypoglycemia, a decrease in the level of amino acids, gastrin, cholecystokinin, cortisol, growth hormone. An increase in secretion is observed with an increase in activity and stimulation with catecholamines β-AR. This takes place during exercise, fasting.

The secretion of glucagon is inhibited by hyperglycemia, excess fatty acids and ketone bodies in the blood, as well as by the action of insulin, somatostatin and secretin.

Disorders of the endocrine function of the pancreas can manifest itself in the form of insufficient or excessive secretion of hormones and lead to sharp disturbances in glucose homeostasis - the development of hyper- or hypoglycemia.

Hyperglycemia - it is an increase in blood glucose. It can be acute or chronic.

Acute hyperglycemia most often it is physiological, since it is usually caused by the flow of glucose into the blood after a meal. Its duration usually does not exceed 1-2 hours due to the fact that hyperglycemia suppresses the release of glucagon and stimulates the secretion of insulin. With an increase in blood glucose above 10 mmol / l, it begins to be excreted in the urine. Glucose is an osmotically active substance, and its excess is accompanied by an increase in the osmotic pressure of the blood, which can lead to dehydration of cells, the development of osmotic diuresis and loss of electrolytes.

Chronic hyperglycemia with which elevated level glucose in the blood lasts hours, days, weeks or more, can cause damage to many tissues (in particular blood vessels) and therefore is considered as a pre-pathological and (or) pathological condition. She happens to be characteristic feature a whole group of metabolic diseases and dysfunctions of the endocrine glands.

One of the most common and severe among them is diabetes(DM), which affects 5-6% of the population. In economically developed countries, the number of diabetic patients doubles every 10-15 years. If diabetes develops as a result of a violation of insulin secretion by β-cells, then it is called type 1 diabetes mellitus - CD-1. The disease can also develop with a decrease in the effectiveness of insulin action on target cells in older people, and it is called type 2 diabetes mellitus - DM-2. At the same time, the sensitivity of target cells to the action of insulin decreases, which can be combined with a violation of the secretory function of β-cells (loss of the 1st phase of food secretion).

A common symptom of CD-1 and CD-2 is hyperglycemia (an increase in fasting venous blood glucose above 5.55 mmol / L). When the blood glucose level rises to 10 mmol / L or more, glucose appears in the urine. It increases the osmotic pressure and the volume of the final urine and this is accompanied by polyuria (an increase in the frequency and volume of excreted urine up to 4-6 l / day). The patient develops thirst and increased fluid intake (polydipsia) due to increased osmotic pressure of blood and urine. Hyperglycemia (especially with DM-1) is often accompanied by the accumulation of products of incomplete oxidation of fatty acids - hydroxybutyric and acetoacetic acids (ketone bodies), which is manifested by the appearance of a characteristic odor of exhaled air and (or) urine, and the development of acidosis. In severe cases, this can cause dysfunction of the central nervous system - the development of a diabetic coma, accompanied by loss of consciousness and death of the body.

Excessive levels of insulin (for example, during insulin replacement therapy or stimulation of its secretion with sulfonylurea drugs) leads to hypoglycemia. Its danger lies in the fact that glucose serves as the main energy substrate for brain cells and when its concentration is lowered or absent, the brain function is disrupted due to dysfunction, damage and (or) death of neurons. If the low glucose level persists long enough, death can occur. Therefore, hypoglycemia with a decrease in blood glucose less than 2.2-2.8 mmol / l) is considered as a condition in which a doctor of any specialty must provide the patient with the first medical assistance.

Hypoglycemia is usually divided into reactive, which occurs after meals and on an empty stomach. The cause of reactive hypoglycemia is increased insulin secretion after a meal with hereditary impairment of sugar tolerance (fructose or galactose) or a change in sensitivity to the amino acid leucine, as well as in patients with insulinoma (β-cell tumor). The causes of fasting hypoglycemia can be - insufficient processes of glycogenolysis and (or) gluconeogenesis in the liver and kidneys (for example, with a deficiency of counterinsular hormones: glucagon, catecholamines, cortisol), excessive utilization of glucose by tissues, insulin overdose, etc.

Hypoglycemia manifests itself in two groups of symptoms. The state of hypoglycemia is stress for the body, in response to the development of which the activity of the sympathoadrenal system increases, the level of catecholamines in the blood increases, which cause tachycardia, mydriasis, tremors, cold sweat, nausea, feeling of severe hunger. The physiological significance of the activation of the sympathoadrenal system by hypoglycemia lies in the activation of the neuroendocrine mechanisms of catecholamines for the rapid mobilization of glucose into the blood and normalization of its level. The second group of signs of hypoglycemia is associated with impaired central nervous system function. They are manifested in a person by a decrease in attention, the development of a headache, a feeling of fear, disorientation, impaired consciousness, convulsions, transient paralysis, coma. Their development is due to a sharp lack of energy substrates in neurons, which cannot receive a sufficient amount of ATP with a lack of glucose. Neurons do not have mechanisms for storing glucose in the form of glycogen, like hepatocytes or myocytes.

A doctor (including a dentist) must be prepared for such situations and be able to provide first aid to patients with diabetes in case of hypoglycemia. Before proceeding with dental treatment, it is necessary to find out what diseases the patient is suffering from. If he has diabetes, the patient should be asked about his diet, the doses of insulin used and the usual physical activity. It should be remembered that the stress experienced during the treatment procedure is an additional risk of hypoglycemia in the patient. Thus, the dentist should have any form of sugar ready - sugar packets, candy, sweet juice or tea. When the patient develops signs of hypoglycemia, the treatment procedure must be stopped immediately and if the patient is conscious, then give him sugar in any form by mouth. If the patient's condition worsens, measures should be taken immediately to provide effective medical care.

In this article, we will tell you which cells are included in the islets of the pancreas? What is their function and what hormones do they release?

A bit of anatomy

In the tissue of the pancreas, there are not only acini, but also the islets of Langerhans. The cells of these formations do not produce enzymes. Their main function is to produce hormones.

These endocrine cells were first discovered in the 19th century. The scientist, after whom these formations are named, was then still a student.

There are not so many islands in the gland itself. Among the entire mass of the organ, the Langerhans zone is 1-2%. However, their role is great. The cells of the endocrine gland produce 5 types of hormones that regulate digestion, carbohydrate metabolism, and response to stress reactions. With the pathology of these active zones, one of the most common diseases of the 21st century develops - diabetes mellitus. In addition, the pathology of these cells causes Zollinger-Ellison syndrome, insulinoma, glucoganoma, and other rare diseases.

It is now known that the islets of the pancreas have 5 types of cells. Let's talk more about their function below.

Alpha cells

These cells make up 15-20% of all islet cells. It is known that humans have more alpha cells than animals. These zones release hormones responsible for the fight and flight response. Glucagon, which is formed here, dramatically increases glucose levels, enhances the work of skeletal muscles, and speeds up the work of the heart. Glucagon also stimulates the production of adrenaline.

Glucagon is designed for short-term exposure. It quickly collapses in the blood. The second significant function of this substance is insulin antagonism. Glucagon is released with a sharp decrease in blood glucose. Such hormones are administered in hospitals to patients with hypoglycemic conditions and coma.

Beta cells

These areas of parenchymal tissue secrete insulin. They are the most numerous (about 80% of the cells). They can be found not only in the islets, there are isolated zones of insulin secretion in the acini and ducts.

The function of insulin is to lower the concentration of glucose. Hormones make cell membranes permeable. Thanks to this, the sugar molecule quickly gets inside. Further, they activate a chain of reactions for the production of energy from glucose (glycolysis) and its storage in reserve (in the form of glycogen), the formation of fats and proteins from it. If insulin is not secreted by cells, type 1 diabetes mellitus develops. If the hormone does not act on the tissue, type 2 diabetes mellitus is formed.

Insulin production is difficult process... Its level can be increased by carbohydrates from food, amino acids (especially leucine and arginine). Insulin rises with an increase in calcium, potassium and some hormonally active substances (ACTH, estrogen, and others).

In the beta zones, C-peptide is also formed. What it is? This word refers to one of the metabolites that is formed during the synthesis of insulin. Recently, this molecule has acquired an important clinical significance. When the insulin molecule is formed, one C-peptide molecule is formed. But the latter has a longer decay time in the body (insulin lives no more than 4 minutes, and C-peptide about 20). C-peptide decreases in type 1 diabetes mellitus (initially little insulin is produced), and increases in type 2 (there is a lot of insulin, but tissues do not react to it), insulinoma.

Delta cells

These are the areas of the pancreatic tissue of Langerhans cells that secrete somatostatin. The hormone inhibits the secretion of enzymes. Also, the substance slows down other organs endocrine system(hypothalamus and pituitary gland). The clinic uses a synthetic analogue or Sandostatin. The drug is actively administered during attacks of pancreatitis, operations on the pancreas.

Delta cells produce a small amount of vasoactive intestinal polypeptide. This substance reduces the formation of hydrochloric acid in the stomach, and increases the content of pepsinogen in gastric juice.

PP cells

These portions of the Langerhans zones produce the pancreatic polypeptide. This substance inhibits the activity of the pancreas and stimulates the stomach. PP cells are very few - no more than 5%.

Epsilon cells

The last parts of the Langerhans zones are extremely rare - less than 1% of the total pool. They synthesize ghrelin. This hormone stimulates the appetite. In addition to pancreasgrelin, the lungs, kidneys, intestines and genitals produce.

The islets of Langerhans in the pancreas are polyhormonal endocrine cells that produce hormones.

They are also called pancreatic islets. As for the sizes, they range from 0.1 to 0.2 mm. The number of islets in adults can reach more than 200,000.

They are named after Paul Langerhans. For the first time, whole groups of cell clusters were discovered in the middle of the 19th century.

These cells work throughout the round-the-clock mode. They produce about 2 mg of insulin per day.

The islets of the pancreas are located in the tail of the pancreas. By weight, they do not exceed more than 3 percent of the total volume of the gland.

Over time, the weight may decrease. When a person reaches 50 years of age, only 1-2 percent remain.

The article will consider what the cells of the pancreas are made of, their functions and other characteristics.

Functional features

The main hormone produced by the islets of Langerhans is insulin. But it should be noted that the zones of Langerhans produce certain hormones with each of their cells.

For example, alpha cells produce glucagon, beta cells produce insulin, and delta cells produce somatostatin.

PP cells - pancreatic polypeptide, epsilon - ghrelin. All hormones affect carbohydrate metabolism, lower or increase blood glucose levels.

Therefore, it must be said that the cells of the pancreas perform the main function associated with maintaining an adequate concentration of deposited and free carbohydrates in the body.

In addition, substances that are produced by the gland affect the formation of fat or muscle mass.

They are also responsible for the functionality of some structures of the brain, associated with the suppression of the secretion of the hypothalamus and pituitary gland.

From this it should be concluded that the main functions of the islets of Langerhans will be to maintain the correct level of carbohydrates in the body and control over other organs of the endocrine system.

They are innervated by the vagus and sympathetic nerves, which are abundantly supplied with blood flow.

The device of the islets of Langerhans

Pancreatic islets have a rather complex structure in the gland. Each of them has an active full-fledged education and functions assigned to them.

The structure of the organ provides an exchange between the glands and biologically active substances of the parenchyma tissue.

Organ cells are intermixed with each other, i.e. they are arranged in a mosaic. The islet in its mature state has a competent organization.

Their structure consists of lobules that surround the connective tissue. There are blood capillaries inside them.

Beta cells are located in the center of the islets, while delta and alpha cells are located in the peripheral region. Therefore, the size of the islets of Langerhans are directly related to their structure.

During the interaction of organ cells, the development of a feedback mechanism is observed. They affect nearby structures as well.

Thanks to the production of insulin, the beta cell function begins to work. They inhibit alpha cells, which in turn activate glucagon.

But alphas also have an effect on delta cells, which are inhibited by the hormone somatostatin. As you can see, each hormone and specific cells are linked to each other.

If there is a malfunction of the immune system, then special bodies may arise in the body that disrupt the work of beta cells.

When destruction is observed, a person develops a pathology called diabetes mellitus.

Islet cell diseases of Langerhans

The cellular system of the islets of Langerhans in the gland can be destroyed.

This occurs during the course of the following pathological processes: autoimmune reactions, oncology, pancreatic necrosis, acute form exotoxicosis, endotoxicosis, systemic diseases.

Elderly people are also susceptible to the disease. Ailments occur in the presence of a serious proliferation of destruction.

This occurs when cells are susceptible to tumor-like phenomena. The neoplasms themselves are hormone-producing, and therefore are accompanied by signs of a malfunction of the hyperfunction of the pancreatic organ.

There are several types of pathologies associated with the destruction of the gland. The critical rate is if the loss is more than 80 percent of the Langerhans islets.

With the destruction of the pancreas, the production of insulin is disrupted, and therefore the hormone is not enough to process the sugar that has entered the body.

In view of this failure, the development of diabetes is observed. It is worth noting that under the first and second degree diabetes mellitus it is necessary to understand two different pathologies.

In the second case, the rise in sugar levels will be related to the fact that cells are not sensitive to insulin. As for the functioning of the Langerhans zones, they work in the same way.

The destruction of hormone-forming structures provokes the development of diabetes mellitus. This phenomenon is characterized by a number of failure symptoms.

These include the appearance of dry mouth, constant thirst. In this case, there may be attacks of nausea or increased nervous irritability.

A person may experience insomnia and a sharp drop in body weight, despite the fact that he eats heavily.

If the sugar level in the body rises, it is possible that an unpleasant acetone odor may appear in the mouth. Possibly impaired consciousness and hyperglycemic coma.

From the above information, it is worth concluding that the cells of the pancreas are capable of producing a number of necessary for the body hormones.

Without them, the full functioning of the body will be disrupted. These hormones carry out carbohydrate metabolism and a number of anabolic processes.

The destruction of the zones will lead to the development of complications associated with the need for hormone therapy in the future.

To avoid the need for such events to develop, it is recommended to adhere to special recommendations specialists.

Basically, they boil down to the fact that it is not worth consuming alcohol in large doses, it is important to treat infectious pathologies and autoimmune disruptions in the body in a timely manner, visit a doctor at the first signs of an illness associated with damage to the pancreas, and other organs included in the gastrointestinal tract.

Medical treatment course

Until recently, diabetes mellitus was treated exclusively with the administration of insulin injections on a regular basis.

Today, the supply of this hormone can be made using special insulin pumps and other devices.

This is really very convenient, because the patient does not need to face regular invasive interventions.

In addition, methods associated with transplanting a gland or hormone-producing sites to a person are actively developing.

Benefits of transplant procedures

The main alternative to replacing glandular tissues is transplantation of the apparatus of the islets of Langerhans.

In such a case, it will not be necessary to install an artificial organ. The transplant will help people suffering from diabetes mellitus in order to restore the structure of beta cells.

The pancreatic gland transplant operation will be performed incompletely.

In accordance with clinical analyzes it was proved that patients with diabetes mellitus at the first stage of pathology with transplanted islet cells were able to restore full regulation of carbohydrate levels.

In order to stop the rejection of donor tissues, it will be necessary to conduct powerful immunosuppressive therapy.

Today stem cells are used to restore these areas. This decision is due to the fact that it is impossible to recruit donor cells for all patients.

Due to limited resources, this alternative is relevant today.

The body needs to restore the susceptibility of immunity. If you do not achieve such a task, then the transplanted areas of the parenchyma will not be able to take root in the body.

They will be rejected, and they may even go through the process of destruction. In view of this, doctors are developing innovative ways in the treatment of pathology.

One of them has become regenerative therapy, which offers new techniques in the areas of therapeutic courses.

In the future, a method of transplanting a pancreas pig into a human is being considered. This procedure is called xenotransplantation in the medical community.

In fact, it is not news that pig gland tissue is used in the treatment of diabetes mellitus.

Parenchymal extracts were used in therapy even before the discovery of insulin by physicians.

The point is that porcine and human pancreas have many similar characteristics. The only thing that sets them apart is one amino acid.

Today, scientists are still developing ways to treat pathology. In view of the fact that diabetes mellitus is a consequence of a violation of the structure of the islets of Langerhans, the study of pathology has great prospects for the future.

Most likely, in the future, at least effective ways treatment of the disease than indicated above.

Preventive goals

In order not to get diabetes, it is worth adhering to special recommendations from leading experts.

This will help not only to avoid this pathology, but also many other health problems.

You can consider hiking, swimming in the pool, cycling, classes in sports groups with like-minded people.

Of course, you have to give up overuse alcoholic drinks, forget about smoking.

And if it so happens that the disease has nevertheless overtaken, you can live interestingly and efficiently, even with such a disappointing diagnosis. You should never lose heart, letting diseases take over you!

Useful video

Each islet of Langerhans plays a very, very important role for the whole organism. Its main role is to control the content of carbohydrates in the blood.

Discovery history

The islet of Langerhans was first described in 1869. The discoverer of these important formations located in the pancreas (mainly in the tail part) was a young student Paul Langerhans. It was he who first examined in a microscope a cluster of cells, which in their own way morphological structure differed from other tissues of the pancreas.

Later it was found that the islets of Langerhans perform an endocrine function. This discovery was made by K.P. Ulezko-Stroganova. In 1889, for the first time, a connection was established between the defeat of the islets of Langerhans and the development of diabetes mellitus.

What could be an islet of Langerhans?

At present, this structure has already been studied quite well. It is now well known that this formation has varieties. At the moment, the following are known:

It is thanks to this diversity that the cells of the islets of Langerhans perform all the duties that are assigned to them.

Alpha cells

This variety accounts for approximately 15-20% of all the islets of Langerhans available. The main task of alpha cells is to produce glucagon. This hormone has a lipid nature and is a kind of insulin antagonist. When released, glucagon is sent to the liver, where, by binding to special receptors, it regulates the production of glucose through the breakdown of glycogen.

Beta cells

The islets of Langerhans of this variety are the most common. They make up approximately 65-80% of the total. It has now been established that their main function is the production of one of the most important hormones - insulin. This substance is a glucagon antagonist. It promotes the activation of the formation of glycogen and its storage in the cells of the liver and muscles. As a result of this process, there is a decrease in the amount

Delta cells

Langerhans islets of this type are not so common. There are only 2-10% of them. Their functional features are now well known. It was found that these cells synthesize somatostatin. The function of this biologically active substance is to suppress the production of somatotropic, thyroid-stimulating and somatotropin-releasing hormone. That is, it acts directly on the hypothalamus, as well as the anterior pituitary gland.

PP cells

Each islet of Langerhans of this type is engaged in the production of a pancreatic polypeptide. Its function has not been fully understood. Currently, he is credited with the properties of suppressing the production of pancreatic juice. In addition, its effect helps to relax the smooth muscles of the gallbladder. IN last years the dependence of the level of production of a given substance on the formation of malignant neoplasms... As a result, it was found that with their development, the level of pancreatic polypeptide increases. So this biologically active substance can be considered a good marker of malignant neoplasms of the pancreas.

Epsilon cells

Such islets of Langerhans are the rarest. Of the total, their number is less than 1%. The main task of these cells is to produce a hormone called ghrelin. This active substance has many functions, but its regulating effect on appetite has been the most studied.

About the pathology of the islets of Langerhans

The defeat of these most important structures has a very serious negative effect on the body. In the event that antibodies are produced to the islets of Langerhans, the number of the latter is progressively reduced. The defeat of more than 90% of the cells is reduced to a critically low level. The result is the development of such dangerous disease like diabetes. Antibodies to islet cells of Langerhans are more likely to appear in relatively young patients.

Serious damage to the population of these hormone-producing cells can cause an inflammatory process in the pancreas - pancreatitis.

How can islet cells be preserved?

To do this, you have to take care of the entire pancreas as a whole. First of all, it is necessary to give up the excesses in alcoholic beverages. The fact is that they are among all food products has the most negative effect on the pancreas. In case of long-term use alcoholic beverages in humans, pancreatitis develops and progresses, which over time can lead to significant damage to the islet cells.

In addition to alcoholic beverages, a large amount of food rich in animal fats has a fairly negative effect on the pancreas. In this case, the situation will be aggravated if, before the feast, the patient long time did not eat anything.

In the event that there is already a chronic inflammatory process in the tissue of the pancreas, it is imperative to consult a specialist - a therapist or a gastroenterologist. Doctors of these specialties will prescribe a rational course of treatment that can significantly slow down the development of pathological changes. In the future, you will have to pass annually ultrasound procedure pancreas, which is performed in conjunction with other organs. In addition, it is necessary to donate for the content of amylase in it.

Determine the onset of development of chronic pancreatitis, in addition to laboratory and instrumental research, the clinic will also help. The main symptom of this disease is the onset. Moreover, this soreness has a shingles in nature and occurs more often after taking a large amount of food rich in animal fats. In addition, the patient after eating may be disturbed by a constant sensation. All these symptoms leave him rather quickly or decrease their severity while taking medications containing pancreatin. Among them, the most popular are the drugs "Creon", "Mezim" and "Pancreatin". When there is inflammatory process in the tissue of the pancreas, it is better to completely stop drinking alcohol. The fact is that even a small amount of it can aggravate the pathological process, thereby significantly harming this organ.

In the 19th century, a young scientist from Germany discovered the heterogeneity of the tissues of the pancreas. The cells, which differed from the main mass, were located in small clusters, islands. The groups of cells were later named after the pathologist - islets of Langerhans (OL).

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

The purpose of the islets of Langerhans

The bulk of the cells in the pancreas (PZh) produce enzymes that aid digestion. The function of the island clusters is different - they synthesize hormones, therefore they are referred to the endocrine system.

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

Most of the pancreatic groups are located in the tail of the pancreas, although chaotic, mosaic inclusions cover the entire exocrine tissue.

OBs are responsible for the regulation of carbohydrate metabolism and support the work of other endocrine organs.

Histological structure

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

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

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

The islets have no ducts, the hormones produced are excreted through the capillary system.

Varieties of cells

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

1. Alpha cells... This group of OB is located along the edge of the islets; their volume is 15-20% of the total size. They synthesize glucagon, a hormone that regulates the amount of glucose in the blood.
2. Beta cells... Are grouped in the center of the islets and make up most their volume, 60-80%. They synthesize insulin, about 2 mg per day.
3. Delta cells... Responsible for the production of somatostatin, they are from 3 to 10%.
4. Epsilon cells... The amount of the total mass is not more than 1%. Their product is ghrelin.
5. PP cells... The hormone pancreatic polypeptide is produced by this part of the OB. They constitute up to 5% of the islets.

Over the course of life, the specific gravity 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 great.

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

1. The main purpose of insulin is to minimize blood sugar levels. It increases the absorption of glucose by the cell membranes, accelerates its oxidation and helps to store it in the form of glycogen. Disruption of hormone synthesis leads to the development of type 1 diabetes. In this case, blood tests show the presence of antibodies to the beta cells. Type 2 diabetes mellitus develops if tissue sensitivity to insulin decreases.
2. Glucagon performs the opposite function - it increases sugar levels, regulates the production of glucose in the liver, and accelerates the breakdown of lipids. Two hormones, complementing the action of each other, harmonize the content of glucose - a substance that ensures the vital activity of the body at the cellular level.
3. Somatostatin slows down the action of many hormones. At the same time, there is a decrease in the rate of absorption of sugar from food, a decrease in the synthesis of digestive enzymes, and a decrease in the amount of glucagon.
4. Pancreatic polypeptide reduces the amount of enzymes, slows down the release of bile and bilirubin. It is believed that it stops the consumption of digestive enzymes, keeping them until the next meal.
5. Ghrelin is considered a hunger or satiety hormone. 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. With an increase in its amount, the production of insulin increases. The synthesis starts at a plasma concentration of 5.5 mmol / L.

It's not just food that can trigger insulin production. In a healthy person, the maximum concentration is observed during the period of strong physical stress and stress.

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

Video about the tasks of insulin in the human body:

The defeat of the endocrine part of the pancreas and its treatment

The cause of the lesion of OL can be genetic predisposition, infection and poisoning, inflammatory diseases, immune problems.

As a result, there is a cessation or a significant decrease in the production of hormones by various islet cells.

As a result of this, the following may develop:

1. Type 1 DM. It is characterized by the absence or deficiency of insulin.
2. SD type 2. It is 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 type 1 diabetes mellitus treatment are the introduction of insulin into the body, the production of which is impaired or reduced. Two types of insulin are used - fast and long acting... The latter type mimics the production of the pancreas hormone.

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

Around the world, 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 islets that are supposed to synthesize hormones.

In recent years, it became known:

• stem cells transplanted into pancreatic tissue take root well and are able to produce hormone in the future, since they begin to work as beta cells;
• OBs produce more hormones if part of the glandular tissue of the pancreas is removed.

This allows patients to opt out of constant admission. medicines, strict diet and return to normal life. The problem remains the immune system, which can reject the planted cells.

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

Successful operations have been performed, after which the need for insulin administration in patients with type 1 diabetes has disappeared. The organ restored the beta-cell population, and the synthesis of its own insulin resumed. After the operation, immunosuppressive therapy was given to prevent rejection.

Video on glucose function and diabetes:

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

Scientists agree that studies of the structural and functional features of the islets of Langerhans are needed due to the large number of important functions that hormones synthesized in them perform.

Constant reception 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 profound disturbances in the functioning of the whole organism, therefore, research continues.