Hormones of the pancreas insulin and glucagon, which produces( isolates, synthesizes), functions, role, action
The pancreas, formed by the primary intestinal cells of the endoderm, has two parts - the exocrine gland, occupying 98% of the whole body of the gland.And pancreatic islets, or islets of Langerhans - the endocrine part, located in small inclusions on the surface of the gland.
The exocrine department is responsible for the processes occurring in the duodenum, as well as the production of gastric juice and its saturation with enzymes that promote the breakdown of carbohydrates, proteins and fats.
The endocrine part produces hormones of carbohydrate synthesis.
Hormones synthesized by the pancreas
The endocrine section is involved in the synthesis of two different types of glandular cells, called insulin and glucagon.Synthesis of glucagon is produced by alpha cells, and beta cells participate in the production of insulin.In addition to alpha and beta cells, the pancreatic islets contain another type - delta cells, which promote the production of somatostatin, an analogue of the hormone produced by the
Insulin, as a polymeric hormone, is two polypeptide yarns connected by a pair of disulfide bonds.It is formed as a result of the action of beta-cell protease on the low-active proinsulin produced by the pancreas.
Regulation of secretory activity
There are two secretory types of insulin - stimulated and basal.
With the basal type, the hormone enters the bloodstream in the absence of stimuli.For example, on an empty stomach, at indicators of a level of sugar in the analysis of blood at practically healthy person no more than 5,5 mmol / l, and insulin level makes 69 mmol / l.
The stimulated type of secretion is caused by exogenous sends, such as amino acids or glucose metabolites that affect calcium exocytosis of insulin and C-peptide into the bloodstream.The secretory function of the hormone of the pancreas is the stimulation of the action of amino acids, in particular leucine or preparations based on sulfonylureas.
There is a short, or an initial stage of insulin stimulation and a long or slow stage.The short stage involves the release into the blood of the hormone enclosed in the granule.The slow phase is characterized by the synthesis of the hormone itself.
Effect and role of hormones
Gastric juice directly affects the exocrine activity of the pancreas.Its functionality depends on the quantitative content of hydrochloric acid in the liquid fraction of the secretion of the gland.It depends on the activity of secretion of secretin and pancreosimin by the small intestine through the cell membrane, as special substances that affect the synthesis of enzymes contained in pancreatic juice.
The use of medications such as vitamin A, morphine, magnesium sulfate, pilocarpine, stimulating the pancreas can lead to an increase in secretory activity.Atropine and histamine lead to inhibition of its functions.
The intrasecretory role of the pancreas in the production of insulin and glucagon is responsible for regulating the process of carbohydrate and lipid metabolism, as well as the process of adsorption of glucose from the blood by tissues, fixing the quantitative glycogen in the liver cells and reducing the level of lipemia.Glucagon promotes suppression of glucose adsorption from blood plasma.
The main hormonal function is the synthesis of lipocaine, or a lipotropic substance that blocks the degeneration of liver fat cells.
Lack of pancreatic hormones
Hormonal failure caused by a lack of hormones in the human body can be associated with many causes, including congenital handicaps.
Insulin deficiency leads to an unpleasant disease, like diabetes mellitus.With an excess of the hormone of the pancreas, there is a process associated with an increase in glucagon content, a decrease in the concentration of sugar in the blood plasma, and an increase in the content of adrenaline.Decreased insulin secretion and an increase in glucagon leads to hypoglycemia - suppression of glucose utilization processes by liver cells.
The deficiency of somatostatin, a pancreas-synthesized somatostatin, analog of the growth hormone produced by the pituitary gland, leads to suppression of the body's internal functions with suppression of developmental processes and metabolic disorders.
Isolation of insulin by pancreas
Insulin is a hormone responsible for reducing the sugar content in the blood plasma and affecting fat metabolism in tissues.
The primary product of beta-cell synthesis is proinsulin.It is not a hormone and carries a biological activity.Its transformation into insulin occurs due to the Golgi complex - intracellular structure with the presence of specific enzymes.After proinsulin is modified into insulin, it is again absorbed by the beta-cell.In it, the hormone is subjected to the process of granulation and enters the vault, from which it can be extracted in case of an acute shortage of it in the body.
Such a need arises every time with an elevated sugar content in the blood plasma.The role of insulin pancreas is to increase the permeability of the cell membrane for glucose with active absorption of the latter.It promotes the transformation of excess sugar into glycogen, and deposits it in muscles and liver.Due to the action of the hormone of the pancreas, the blood sugar level in the blood is significantly reduced.
What is behind the increased insulin levels?
High insulin values in blood tests indicate that the body undergoes low resistance to excessive amounts of the hormone.This may be due to the disabling of receptors responsible for carbohydrate metabolism.As a result, a disease develops, such as type 2 diabetes, or non-insulin-dependent diabetes mellitus, in which the pancreas produces excess hormone, and the internal receptors do not respond to it: carbohydrates that come with food are not absorbed by the body, and the sugar level in the blood plasmaGives good results.
Insulin injections are contraindicated in this type of diabetes, because the pancreas produces hormone in excess.The most unpleasant symptom in atypical diabetes is debilitating thirst, as excess glucose absorbs intracellular moisture, causing dehydration of the body.
Factors affecting the release of insulin
The pancreas of a healthy person is a very subtle instrument for tuning the entire body.It reacts very sensitively to changes caused by the glucose content in the blood, releasing a large amount of insulin with an excess of sugar and reducing it with its lack.
Diabetes leads to impaired pancreatic function with oppression of the islets of Langerhans - the endocrine gland.Therefore, there are contraindications to the consumption of sugar-containing foods saturated with easily digestible carbohydrates, such as sweets, chocolate, honey or jam, as well as sugar, leading to the depletion and further death of insulin-synthesizing beta-cells.
Glucagon - a hormone synthesized by the pancreas
At the molecular level is a polypeptide consisting of a single filament with a mass of 3,500 daltons.Glucagon is synthesized by alpha cells of the endocrine department.Mucous membrane of the intestine is entero-glucagon, being synergist of adrenaline, it functions directly in the cells of the liver.Its realization is carried out through cyclic AMP and adenylate cyclase.The pancreatic hormone is responsible for controlling the rate of lipolysis, as well as glycogenolysis of the liver.