Hormones of the pancreas

Hormones are substances synthesized by large endocrine glands and special glandular cells in the internal organs. Their role for the body is to control and regulate metabolic biochemical processes.

Pancreatic hormones are produced in the digestive system, associated with the digestion of food and the assimilation of its beneficial components. Through the general system of hypothalamic-pituitary management are subject to the influence of the need for changes in metabolism. To understand the features of the pancreas, a small lesson of anatomy and physiology is needed.

Structure and function of

The pancreas is the largest among the endocrine glands. It is located retroperitoneal. In the structure distinguish: a round head, a broader body and an elongated tail. The head is the widest part, surrounded by the tissues of the duodenum. The width is normally 5 cm, the thickness is 1.5-3 cm.

Body - has a front, back and bottom faces. The front is adjacent to the back of the stomach. The lower edge reaches the second lumbar vertebra. The length is 1.75-2.5 cm. The tail is directed to the rear and to the left. It contacts the spleen, adrenal gland and left kidney. The total length of the gland is 16-23 cm, and the thickness decreases from three cm in the head region to 1.5 cm in the tail.

Along the gland is the central( Virsungiev) duct. On it, the digestive secret directly enters the duodenum. The structure of the parenchyma consists of two main parts: exocrine and endocrine. They differ in functional meaning and structure.

Exocrine - takes up to 96% of the mass, consists of alveoli and a complex system of excretory ducts, which "respond" to the production and isolation of digestive juice enzymes to ensure the digestion of food in the intestine. Their lack is heavily reflected in the processes of assimilation of proteins, fats and carbohydrates. The endocrine part is formed by the accumulation of cells into special islets of Langerhans. It is here that secretion of hormonal substances important for the body occurs.

Participation in the synthesis of different hormones from the pancreas side is not the same

What hormones are produced by the pancreas?

The opportunities of science every year expand information about the role of hormones in the pancreas, allow us to identify new forms, their influence and interaction. The pancreas secretes hormones involved in metabolism in the body:

• insulin;
• glucagon;
• somatostatin;
• pancreatic polypeptide;
• gastrin.

Until some time, the substance of the C-peptide belonged to the hormones of the pancreas. Then it was proved that it is a part of the insulin molecule, torn off during synthesis. The determination of this substance remains important in the analysis of the detection of insulin in the blood, since its volume is proportional to the basic hormone. This is used in clinical diagnosis.

In the endocrine gland cells are divided into four main types:

• alpha cells - make up to 20% of the total mass, they synthesize glucagon;
• beta cells - the main variety, they account for 65-80%, produce the necessary insulin, for these cells, the gradual destruction with age of a person is characteristic, their number decreases with old age;
• delta cells - occupy about 1/10 of the total, they produce somatostatin;
• PP-cells - are detected in a small amount, are characterized by the ability to synthesize the pancreatic polypeptide;
• G-cells - produce gastrin( together with the gastric mucosa).

The histological structure of the parenchyma allows different types of cells to be isolated

Characteristics of pancreatic hormones

We will consider the main functions of hormones in their structure, action on the organs and tissues of the human body.

Insulin

Represents a polypeptide in structure. The structure consists of two chains of amino acids connected by "bridges".Nature formed the most similar in structure to human insulin in pigs and rabbits. These animals proved to be the most suitable for the preparation of drugs from the hormones of the pancreas. The hormone is produced by beta cells from proinsulin by separation of the c-peptide. The structure where this process takes place is revealed - the Golgi apparatus.

The main task of insulin is to regulate the concentration of glucose in the blood with the help of its penetration into the fat and muscle tissues of the body. Insulin promotes increased absorption of glucose( increases the permeability of cell walls), its accumulation in the form of glycogen in muscles and liver. Stocks are used by the body with a sharp increase in energy requirements( increased physical activity, disease).

However, insulin interferes with this process. It also does not allow the fission of fats and form ketone bodies. Stimulates the synthesis of fatty acids from carbohydrate metabolism products. Reduces cholesterol levels, prevents atherosclerosis. The role of the hormone in protein metabolism is important: it activates the expenditure of nucleotides and amino acids for the synthesis of DNA, RNA, nucleic acids, and retards the breakdown of protein molecules.

These processes are important for the formation of immunity. Insulin promotes the penetration of cells of amino acids, magnesium, potassium, phosphates. The regulation of the amount of insulin needed depends on the level of glucose in the blood. If there is hyperglycemia, then the production of the hormone increases, and vice versa.

In the medulla oblongata there is a zone called the hypothalamus. It contains nuclei, where information is received about the excess of glucose. The reverse signal goes through the nerve fibers to the beta cells of the pancreas, then the formation of insulin is enhanced.

Hypothalamus - the guiding insulin production is the highest "instance" of

When the glucose level in the blood decreases( hypoglycemia), the hypothalamic nuclei retard their activity, correspondingly, the secretion of insulin decreases. Thus, higher nervous and endocrine centers regulate the metabolism of carbohydrates. On the part of the autonomic nervous system, the regulation of insulin production is influenced by the vagus nerve( stimulates), sympathetic( blocks).

It is proven that glucose is able to directly act on the beta cells of the islets of Langerhans and release insulin. Of great importance is the activity of an insulin-damaging enzyme( insulinase).It is maximally concentrated in the liver parenchyma and in muscle tissue. When blood passes through the liver, half of the insulin is destroyed.

Glucagon

A hormone, like insulin, is a polypeptide, but there is only one chain of amino acids in the molecule structure. By its functions it is considered an antagonist of insulin. It is formed in alpha cells. The main value is the cleavage of fatty lipids, an increase in the concentration of glucose in the blood.

Together with another hormone that also secretes the pancreas, somatotropin and adrenal hormones( cortisol and adrenaline), it protects the body from a sharp drop in energy material( glucose).In addition, the role of

• in the enhancement of renal blood flow is important;
• normalization of cholesterol;
• activation of the ability of the hepatic tissue to regenerate;
• in the removal of sodium from the body( relieves edema).

The mechanism of action is related to the interaction with the cell membrane receptors. As a result, the activity and concentration in the blood of the enzyme adenylate cyclase increases, which stimulates the process of glycogen degradation to glucose( glycogenolysis).Regulation of secretion is carried out by the level of glucose in the blood. When the increase is inhibited the production of glucagon, a decrease activates production. The central part is exerted by the anterior pituitary gland.

Somatostatin

The biochemical structure refers to polypeptides. It is able to inhibit up to complete cessation the synthesis of such hormones as insulin, thyreotropic, somatotropin, glucagon. It is this hormone that can inhibit the secretion of digestive enzymes and bile.

Dysfunction contributes to pathologies associated with the digestive system. It inhibits the secretion of glucagon by blocking the entry of calcium ions into the alpha cells. The action is affected by growth hormone growth hormone in the anterior lobe of the pituitary gland through an increase in alpha cell activity.

One of the hormones that is produced by the gland

The polypeptide

Hormone synthesizes PP cells. It is considered antagonist cholecystokinin. It suppresses secretory functions and activates the production of gastric juice. The action has not been sufficiently studied. It is known that it participates in inhibition of rapid entry into the blood of bilirubin, trypsin, bile, relaxation of the muscular wall of the gallbladder, inhibits the production of certain digestive enzymes.

Gastrin

It is produced by two organs - the stomach and pancreas( in a smaller volume).It controls the activity of all the hormones involved in digestion. Three types are known for the number of amino acid composition: microgastrin - in the structure of the molecule 14 amino acids, small - in the composition of 17 varieties, large - the formula contains 34 amino acids. Violation of the synthesis causes a malfunction in the work of the stomach and intestines. In clinical practice, analysis is important for gastrin.

Other active substances

Other but not less important hormones synthesized in the pancreas have been identified:

• Lipocaine - stimulates the formation of lipids and oxidation of fatty acids, protects the liver from fatty degeneration.
• Vagotonin - increases the tone of the vagus nerve, strengthens its effect on internal organs.
• Centropinin - excites the respiratory center of the medulla oblongata, helps in relaxing the muscles of the bronchi. Strengthens the possibility of hemoglobin to bind with oxygen and this improves its transport in the tissue.
• Tyroliberin ( other names are "thyrotropin-releasing factor", "thyreolin") - the main place of synthesis is the hypothalamus, but in small amounts it is formed in the islets of Langerhans, the gastrointestinal tract, in other nerve nuclei of the brain, in the epiphysis. Promotes increased production in the anterior lobe of the pituitary gland of thyroid-stimulating hormone and prolactin, which provides lactation in women after childbirth.

The substance is responsible for the processes occurring in the liver

What are the drugs used for the hormones of the pancreas?

Most known are insulin preparations manufactured by various pharmaceutical companies. Their differences are in three features:

• in origin;
• speed of approach and duration of action;
• cleaning method, and also the degree of purity.

Depending on the origin, the following are isolated:

• natural( natural) remedies made from pancreas of pigs and cattle( Actrapid, Insulin tape GPP, Ultralente MC, Monotard MS);
• synthetic - obtained by fine methods of genetic engineering, compilation of DNA combinations( Actrapid NM, Isofan NM, Homophan, Humulin and others).

By the time of the beginning of the effect and the duration of the action, drugs are distinguished:

• of a fast and simultaneously short action( Insuman Rapid, Actrapid, Actrapid NM), they start to act after 15-30 minutes after admission, the duration is up to 8 hours;
• of medium duration -( Humulin N, Insulong SPP, Humulin Ribe, Monotard MS), beginning in 1-2 hours, duration up to 24 hours);
• of medium duration + short-acting insulin( Actrafan NM, Insuman com., Humulin M-1) is a large group in which the parameters for each drug are determined, but the action begins all after 30 minutes.

Glucagon is indicated for any hypoglycemic condition

Synthetic drug Glucagon is administered intravenously as an aid against an insulin overdose. Somatostatin of close animals is used to create medicines in the therapy of diseases associated with hyper growth hormone. It is very important for acromegaly. The disease occurs in adulthood, is manifested by increased growth of the bones of the skull, feet, the increase in certain parts of the body.

The biological role of pancreatic hormones is indispensable for a healthy body. In practice, they ensure the transfer of food to the necessary energy. In the cells that produce hormones, there are no special ducts or excretory pathways. They secret their secret directly into the bloodstream and quickly spread throughout the body. Disrupted functions, production failures threaten a person with dangerous diseases.