Table of glands and their functions. Depending on genetic characteristics and origin

Endocrine glands, or endocrine glands (ZHVS) are called glandular organs, the secret of which enters directly into the blood. Unlike the glands of external secretion, the products of which enter the cavities of the body that communicate with the external environment, ZhVS do not have excretory ducts. Their secrets are called hormones. Released into the blood, they are carried throughout the body and have effects on various organ systems.

What are the endocrine glands

The organs related to the endocrine glands and the hormones they produce are presented in the table:

* The pancreas has both external and internal secretions.

In some sources, the thymus (thymus gland) is also referred to the endocrine glands, in which the substances necessary to regulate the functioning of the immune system are formed. Like all VVS, it does not really have ducts and secretes its products directly into the bloodstream. However, the thymus actively functions until adolescence, then it involution occurs (replacement of the parenchyma with adipose tissue).

Anatomy and functions of the endocrine apparatus

All endocrine glands have different anatomy and a set of synthesized hormones, therefore, the functions of each of them are radically different.

These include the hypothalamus, pituitary, epiphysis, thyroid, parathyroid, pancreas and gonads, adrenal glands.

Hypothalamus

The hypothalamus is an important anatomical formation of the central nervous system, which has a powerful blood supply and is well innervated. In addition to regulating all autonomic functions of the body, it secretes hormones that stimulate or inhibit the work of the pituitary gland (releasing hormones).

Activating agents:

• thyroliberin;
• corticoliberin;
• gonadoliberin;
• somatoliberin.

Hypothalamic hormones that inhibit the activity of the pituitary gland include:

• somatostatin;
• melanostatin.

Most releasing factors of the hypothalamus are not selective. Each acts immediately on several tropic hormones of the pituitary gland. For example, thyroliberin activates the synthesis of thyrotropin and prolactin, and somatostatin inhibits the formation of most peptide hormones, but mainly growth hormone and corticotropin.

In the anterior-lateral region of the hypothalamus, there are clusters of special cells (nuclei) in which vasopressin (antidiuretic hormone) and oxytocin are formed.

Vasopressin, acting on the receptors of the distal renal tubules, stimulates the reverse reabsorption of water from the primary urine, thereby retaining fluid in the body and reducing diuresis. Another effect of the substance is an increase in total peripheral vascular resistance (vasospasm) and an increase in blood pressure.

Oxytocin has to a small extent the same properties as vasopressin, but its main function is to stimulate labor (uterine contractions), as well as increase the secretion of milk from the mammary glands. The task of this hormone is male body has not been established to date.

Pituitary

The pituitary gland is the central gland in the human body that regulates the work of all pituitary-dependent glands (except for the pancreas, pineal gland and parathyroid glands). It is located in the Turkish saddle of the sphenoid bone, has very small dimensions (weight about 0.5 g; diameter - 1 cm). It is divided into 2 lobes: anterior (adenohypophysis) and posterior (neurohypophysis). The pituitary stalk, which is connected with the hypothalamus, delivers releasing hormones to the adenohypophysis, and oxytocin and vasopressin to the neurohypophysis (where they accumulate).

The pituitary gland in the Turkish saddle of the sphenoid bone. The adenohypophysis is colored bright pink, the neurohypophysis is painted pale pink.

The hormones by which the pituitary gland controls the peripheral glands are called tropic. The regulation of the formation of these substances occurs not only due to the releasing factors of the hypothalamus, but also the products of the activity of the peripheral glands themselves. In physiology, this mechanism is called negative feedback. For example, with excessively high production of thyroid hormones, thyrotropin synthesis is inhibited, and with a decrease in the level of thyroid hormones, its concentration increases.

Prolactin is the only non-tropic hormone of the pituitary gland (that is, it does not realize its effect at the expense of other glands). Its main task is to stimulate lactation in lactating women.

Somatotropic hormone (somatotropin, growth hormone, growth hormone) also conditionally refers to tropic. The main role of this peptide in the body is to stimulate development. However, this effect is not realized by STG itself. It activates the formation of so-called insulin-like growth factors (somatomedins) in the liver, which have a stimulating effect on the development and division of cells. STH causes a number of other effects, for example, it is involved in carbohydrate metabolism by activating gluconeogenesis.

Adrenocorticotropic hormone (corticotropin) is a substance that regulates the functioning of the adrenal cortex. However, ACTH has almost no effect on the formation of aldosterone. Its synthesis is regulated by the renin-angiotensin-aldosterone system. Under the action of ACTH, the production of cortisol and sex steroids in the adrenal glands is activated.

Thyroid-stimulating hormone(thyrotropin) has a stimulating effect on the function of the thyroid gland, increasing the formation of thyroxine and triiodothyronine.

Gonadotropic hormones - follicle-stimulating (FSH) and luteinizing (LH) activate the activity of the gonads. In men, they are necessary for the regulation of testosterone synthesis and the formation of spermatozoa in the testicles, in women - for the implementation of ovulation and the formation of estrogens and progestogens in the ovaries.

epiphysis

The pineal gland is a small gland weighing only 250 mg. This endocrine organ is located in the region of the midbrain.

The function of the pineal gland has not yet been fully understood. The only known compound is melatonin. This substance is the "internal clock". By changing its concentration, the human body recognizes the time of day. It is with the function of the epiphysis that adaptation to other time zones is associated.

Thyroid

The thyroid gland (TG) is located on the front of the neck under thyroid cartilage larynx. It consists of 2 lobes (right and left) and the isthmus. In some cases, an additional pyramidal lobe departs from the isthmus.

The size of the thyroid gland is very variable, therefore, when determining compliance with the norm, they talk about the volume of the thyroid gland. In women, it should not exceed 18 ml, in men - 25 ml.

In the thyroid gland, thyroxine (T4) and triiodothyronine (T3) are formed, which play an important role in human life, affecting the metabolic processes of all tissues and organs. They increase the oxygen consumption of cells, thereby stimulating the production of energy. With their deficiency, the body suffers from energy hunger, and with an excess, dystrophic processes develop in tissues and organs.

These hormones are especially important during the period of intrauterine growth, since their deficiency disrupts the formation of the fetal brain, which is accompanied by mental retardation and impaired physical development.

Calcitonin is produced in C-cells of the thyroid gland, the main function of which is to reduce the level of calcium in the blood.

parathyroid glands

The parathyroid glands are located on the posterior surface of the thyroid gland (in some cases they are included in the thyroid gland or are located in atypical places - the thymus, the paratracheal groove, etc.). The diameter of these rounded formations does not exceed 5 mm, and the number can vary from 2 to 12 pairs.

Schematic arrangement of the parathyroid glands.

The parathyroid glands produce parathyroid hormone, which affects the phosphorus-calcium metabolism:

• increases bone resorption, releasing calcium and phosphorus from bones;
• increases the excretion of phosphorus in the urine;
• stimulates the formation of calcitriol in the kidneys (the active form of vitamin D), which leads to increased absorption of calcium in the intestine.

Under the action of parathyroid hormone, there is an increase in the level of calcium and a decrease in the concentration of phosphorus in the blood.

adrenal glands

The right and left adrenal glands are located above the upper poles of the respective kidneys. The right one resembles a triangle in outline, and the left one resembles a half moon. These glands weigh about 20 g.

Sectional view of the adrenal glands (diagram). The cortical substance is highlighted in light, the medulla is highlighted in dark.

On a cut in the adrenal gland, cortical and medulla substances are isolated. The first contains 3 microscopic functional layers:

• glomerular (synthesis of aldosterone);
• beam (production of cortisol);
• reticular (synthesis of sex steroids).

Aldosterone is responsible for the regulation of electrolyte balance. Under its action, the reverse reabsorption of sodium (and water) and the excretion of potassium increase in the kidneys.

Cortisol has an effect on the body various effects. It is a hormone that adapts a person to stress. Main functions:

• increase in blood glucose levels due to the activation of gluconeogenesis;
• increased protein breakdown;
• specific effect on fat metabolism (increased lipid synthesis in the subcutaneous fat of the upper body and increased decay in the tissue of the extremities);
• decreased reactivity of the immune system;
• inhibition of collagen synthesis.

Sex steroids (androstenedione and dihydroepiandrosterone) cause effects similar to testosterone, but are inferior to it in their androgenic activity.

In the adrenal medulla, adrenaline and norepinephrine are synthesized, which are hormones of the sympathetic-adrenal system. Their main effects:

• increased heart rate, increased cardiac output and blood pressure;
• spasm of all sphincters (urinary retention and defecation);
• slowing down the secretion of exocrine glands;
• an increase in the lumen of the bronchi;
• pupil dilation;
• increased blood glucose levels (activation of gluconeogenesis and glycogenolysis);
• acceleration of metabolism in muscle tissue (aerobic and anaerobic glycolysis).

The action of these hormones is aimed at the rapid activation of the body in emergency conditions (the need for flight, protection, etc.).

Endocrine apparatus of the pancreas

According to its significance, the pancreas is an organ of mixed secretion. It has a ductal system, through which digestive enzymes enter the intestines, but it also contains an endocrine system - the islets of Langerhans, most of which are located in the tail. They produce the following hormones:

• insulin (islet beta cells);
• glucagon (alpha cells);
• somatostatin (D-cells).

Insulin regulates various types of metabolism:

• reduces blood glucose levels by stimulating the entry of glucose into insulin-dependent tissues (adipose tissue, liver and muscles), inhibits the processes of gluconeogenesis (glucose synthesis) and glycogenolysis (glycogen breakdown);
• activates the production of protein and fats.

Glucagon is a contrainsular hormone. Its main function is the activation of glycogenolysis.

Somatostatin inhibits the production of insulin and glucagon.

gonads

The gonads produce sex steroids.

In men, testosterone is the main sex hormone. It is produced in the testicles (Leydig cells), which are normally located in the scrotum and have an average size of 35-55 and 20-30 mm.

The main functions of testosterone:

• stimulation of skeletal growth and distribution of muscle tissue according to the male type;
• the development of the genitals, vocal cords, the appearance of male-type body hair;
• formation of a male stereotype of sexual behavior;
• participation in spermatogenesis.

For women, the main sex steroids are estradiol and progesterone. These hormones are produced in the ovarian follicles. In the maturing follicle, the main substance is estradiol. After the rupture of the follicle at the time of ovulation, a corpus luteum forms in its place, which secretes mainly progesterone.

The ovaries in women are located in the small pelvis on the sides of the uterus and measure 25-55 and 15-30 mm.

The main functions of estradiol:

• the formation of physique, the distribution of subcutaneous fat according to the female type;
• stimulation of proliferation of the ductal epithelium of the mammary glands;
• activation of the formation of the functional layer of the endometrium;
• stimulation of the ovulatory peak of gonadotropic hormones;
• formation female type sexual behavior;
• stimulation of positive bone metabolism.

The main effects of progesterone:

• stimulation of the secretory activity of the endometrium and its preparation for embryo implantation;
• suppression of the contractile activity of the uterus (preservation of pregnancy);
• stimulation of differentiation of the ductal epithelium of the mammary glands, preparing them for lactation.

And their hormones (also called secrets) make it work. endocrine system organism. Secrets are secreted into the internal environment of the body, since these organs do not have ducts that allow secretions to be removed into the cavity or onto the surface of the skin.

Organs that secrete biologically active substances are divided into three large groups: external, internal and mixed secretion.

• The organs of external secretion include sweat, sebaceous, salivary and gastric glands. The released secret passes through the ducts to the surface of the skin, oral cavity or into the stomach.
• The group of endocrine organs of internal secretion includes the pituitary gland, adrenal glands, thyroid and parathyroid glands. Blood is the main transport of these secrets. Hormones secreted by glands with internal secretion come here.
• The thymus, pancreas and gonads are classified as mixed secretions. This also includes the placenta. They are traditionally referred to as the endocrine system, since the hormone can be released both outside and inside the body.

The main function of the endocrine system is the regulation of processes occurring in the body. The maturation of the egg or sperm, the onset of puberty or menopause, depression, insomnia and excessive activity - the consequences of the work of substances can be different, and their action is complex and balanced.

Anatomically, this area of ​​the brain is not an organ of secretion, as it is represented by neurons. But the latter can secrete substances that activate the work of the pituitary gland - the next representative of the organs of internal secretion.

The work is presented in this way. Hormones are synthesized in neurons and produced in the neurohypophysis, from which they enter the bloodstream and reach the target organ. The main secrets of the gland and those hormones that are produced under their action are vasopressin.

• Prolactin is responsible for the onset of the lactation period and the formation of milk in pregnant women.
• Oxytocin stimulates the work of smooth muscles, strengthens the muscles and contractile activity of muscle fibers. It is indicated for pregnant women with low activity of the muscle fibers of the uterus, as well as with muscle hypotrophy.
• Vasopressin regulates the excretion of water by the kidneys, increases the tone of the smooth muscles of the digestive tract, and with an excess of secretion, it increases blood pressure.

Pituitary

The apex of the endocrine glands is the pituitary gland. It is located in the center of the brain and its dimensions do not exceed 5x5 mm. There are several targets where they enter. It regulates the work of other glands, the reproductive system, metabolic processes and human growth.

The pituitary gland secretes corticotropin, thyrotropic and gonadotropic secretions.

• Corticotropin regulates the work of the adrenal glands, stimulates the release of hormones in them
• Thyrotropin stimulates the production of: thyroxine and triiodothyronine, which further regulate metabolic processes and the condition of the skin
• Follitropin is responsible for the formation of follicles, and lutropin is responsible for the rupture of the follicle membrane and the formation of the corpus luteum.
• Somatotropin is the most important hormone formed by the endocrine gland. Being released into the blood and cavities, it increases RNA synthesis, regulates carbohydrate metabolism, and stimulates growth processes. The lack of somatotropin in childhood leads to lifelong.

Thyroid

The organ in the form of a shield is located on the front wall of the neck and reaches a mass of 20-23 g. Under the action of the pituitary gland, the synthesis of secrets in the A-cells of the thyroid gland is activated, after which they are released into the blood, where they bind with carrier proteins and reach target organs.

The thyroid and parathyroid glands secrete thyroxine, calcitonin and triiodothyronine. The first two hormones are abbreviated as T4 and T3.

• - hormonal regulator of metabolism and peptide synthesis. Participates in the development and growth of the body. Excess T4 is a common endocrine disease, when the hormone produced is rejected by the body and is regarded by it as a foreign substance.
• Triiodothyronine, the production of which only a quarter occurs in the thyroid gland, is also involved in the regulation of metabolic processes and protein synthesis, being released from T4.
• takes an active part in strengthening bone tissue, reduces the concentration of phosphorus and calcium in the blood, activates the excretion of phosphates by the kidneys.

pancreas

Mixed glands produce hormones of both intra- and exocrine function. The last function is performed by small pancreatic islets, which are pierced by capillaries.

Hormones formed by islets enter these capillaries through the endothelial membranes and are carried by the blood throughout the body.

• - secretion of the hormone occurs in the A-cells of the islets. Its function is aimed at converting incoming glycogen into a more digestible form - glucose.
• - the most important hormone responsible for the regulation of blood glucose levels. Each time glucose enters the bloodstream, insulin binds it into animal starch, which is burned by muscle fibers. A decrease in insulin secretion leads to diabetes mellitus, and an increase leads to excessive consumption of glucose by tissues, the deposition of sugars and hypoglycemic coma.
• Pancreatic polypeptide and somatostatin are substances of the general hormonal background that do not have great importance in clinical practice.

adrenal glands

This is a paired endocrine organ that forms the signaling hormonal systems of the body. It is located above the upper region of the kidneys and reaches a mass of no more than 8 g. The secretion occurs in the cortex of the organ.

The development and functioning of the cortex is completely dependent on the pituitary gland.

• - a signaling substance that increases the heartbeat, constricts blood vessels and accelerates the synthesis of glucose. The excitability of the retina, vestibular and hearing aids increases - the body works in an "emergency" mode under the influence of external stimuli.
• - a harbinger of adrenaline. It is synthesized before adrenaline, and in case of extreme stimuli it is immediately transformed into its final form.
• - regulates salt metabolism, preventing hyperkalemia.

These include the testes and ovaries. Knowing where the hormones secreted by the endocrine glands go, it is easy to understand the principle of the sex glands.

The testicles produce male sex hormones (androgens) that affect the development and functioning of the reproductive system.

The ovaries produce - female sex hormones responsible for the onset of pregnancy, childbearing functions, as well as stimulating the production of breast milk.

Conclusion

It is impossible to say which glands are more important for the body, because their system of work is interconnected and dependent on each hormone. The hormones formed by the endocrine glands are constantly secreted, providing vital important features organism.

Violations in the work of one endocrine organ will entail changes not only in other glands, but in all organs. For this reason, most diagnosis begins with an analysis of the endocrine system to determine which hormones are found outside the normal range.

Bibliography

1. Grebenshchikov Yu.B., Moshkovsky Yu.Sh., Bioorganic chemistry // Physicochemical characteristics, structure and functional activity of insulin. - 1986. - p.296.
2. Filippovich Yu.B., Fundamentals of biochemistry // Hormones and their role in metabolism. - 1999. - pp. 451-453, 455-456, 461-462.
3. Human Physiology / ed. G. I. Kositsky. - 3rd ed., revised. and additional - M.: Medicine, 1985, 544 p.;
4. Tepperman J., Tepperman H., Physiology of metabolism and the endocrine system. Introductory course. - Per. from English. - M.: Mir, 1989. - 656 p.; Physiology. Fundamentals and functional systems: a course of lectures / ed. K. V. Sudakova. – M.: Medicine. - 2000. -784 p.;
5. Agadzhanyan M. A., Smirnov V. M., Normal Physiology: A Textbook for Medical Students. - M .: LLC publishing house "Medical Information Agency", - 2009. - 520 p.;
6. Anosova L. N., Zefirova G. S., Krakov V. A. Brief endocrinology. – M.: Medicine, 1971.

1. The physiological role of the endocrine glands. Characteristics of the action of hormones.

The endocrine glands are specialized organs that have a glandular structure and secrete their secret into the blood. They do not have excretory ducts. These glands include: pituitary gland, thyroid gland, parathyroid gland, adrenal glands, ovaries, testicles, thymus gland, pancreas, pineal gland, APUD - system (system for capturing amine precursors and their decarboxylation), as well as the heart - produces atrial sodium - diuretic factor, kidneys - produce erythropoietin, renin, calcitriol, liver - produces somatomedin, skin - produces calciferol (vitamin D 3), gastrointestinal tract - produces gastrin, secretin, cholecystokinin, VIP (vasointestinal peptide), GIP (gastric inhibitory peptide).

Hormones perform the following functions:

Involved in maintaining homeostasis internal environment, control glucose levels, extracellular fluid volume, blood pressure, electrolyte balance.

Provide physical, sexual, mental development. They are also responsible for the reproductive cycle ( menstrual cycle, ovulation, spermatogenesis, pregnancy, lactation).

Control the formation and use nutrients and energy resources in the body

Hormones provide the processes of adaptation of physiological systems to the action of stimuli of the external and internal environment and participate in behavioral reactions (need for water, food, sexual behavior)

They are mediators in the regulation of functions.

The endocrine glands create one of two systems for regulating functions. Hormones differ from neurotransmitters in that they alter the chemical reactions in the cells they act on. Mediators cause an electrical reaction.

The term "hormone" comes from the Greek word HORMAE - "I excite, encourage."

Classification of hormones.

By chemical structure:

1. Steroid hormones - derivatives of cholesterol (hormones of the adrenal cortex, gonads).

2. Polypeptide and protein hormones (anterior pituitary, insulin).

3. Derivatives of the amino acid tyrosine (adrenaline, norepinephrine, thyroxine, triiodothyronine).

Functionally:

1. Tropic hormones (activate the activity of other endocrine glands; these are hormones of the anterior pituitary gland)

2. Effector hormones (act directly on metabolic processes in target cells)

3. Neurohormones (released in the hypothalamus - liberins (activating) and statins (inhibiting)).

properties of hormones.

Remote nature of action (eg, pituitary hormones affect the adrenal glands),

Strict specificity of hormones (the absence of hormones leads to the loss of a certain function, and this process can be prevented only by the introduction of the necessary hormone),

They have high biological activity (they are formed in low concentrations in the fatty acid.),

Hormones do not have ordinary specificity,

They have a short half-life (quickly destroyed by tissues, but have a long hormonal effect).

2. Mechanisms of hormonal regulation of physiological functions. Its features in comparison with nervous regulation. Systems of direct and reverse (positive and negative) links. Methods for studying the endocrine system.

Internal secretion (incretion) is the release of specialized biologically active substances - hormones- into the internal environment of the body (blood or lymph). Term "hormone" was first applied to secretin (hormone of the 12th intestine) by Starling and Beilis in 1902. Hormones differ from other biologically active substances, for example, metabolites and mediators, in that, firstly, they are formed by highly specialized endocrine cells, and secondly, in that they influence tissues remote from the gland through the internal environment, i.e. have a distant effect.

The most ancient form of regulation is humoral-metabolic(diffusion of active substances to neighboring cells). It occurs in various forms in all animals, especially clearly manifested in the embryonic period. The nervous system, as it developed, subjugated the humoral-metabolic regulation.

True endocrine glands appeared late, but on early stages evolution is neurosecretion. Neurosecretes are not neurotransmitters. Mediators are simpler compounds, they work locally in the area of ​​the synapse and are quickly destroyed, while neurosecretions are protein substances that break down more slowly and work at a great distance.

With the advent circulatory systems neurosecrets began to be released into her cavity. Then arose special education for the accumulation and change of these secrets (in annelids), then their appearance became more complicated and the epithelial cells themselves began to secrete their secrets into the blood.

Endocrine organs have a very different origin. Some of them arose from the sense organs (pineal gland - from the third eye). Other endocrine glands were formed from the glands of external secretion (thyroid). Branchiogenic glands were formed from the remnants of provisional organs (thymus, parathyroid glands). Steroid glands originated from the mesoderm, from the walls of the coelom. Sex hormones are secreted by the walls of the glands containing the sex cells. thus, different endocrine organs have different origins, but they all arose as an additional mode of regulation. There is a single neurohumoral regulation in which the nervous system plays a leading role.

Why was such an additive to nervous regulation formed? nerve connection- fast, accurate, addressed locally. Hormones - act wider, slower, longer. They provide a long-term reaction without the participation of the nervous system, without constant impulsation, which is uneconomical. Hormones have a long aftereffect. When a quick reaction is required, the nervous system works. When a slower and more stable reaction to slow and long-term changes in the environment is required, hormones work (spring, autumn, etc.), providing all adaptive changes in the body, up to sexual behavior. In insects, hormones provide complete metamorphosis.

The nervous system acts on the glands in the following ways:

1. Through the neurosecretory fibers of the autonomic nervous system;

2. Through neurosecrets - the formation of the so-called. releasing or inhibiting factors;

3. The nervous system can change the sensitivity of tissues to hormones.

Hormones also affect nervous system. There are receptors that respond to ACTH, to estrogen (in the uterus), hormones affect GNI (sexual), the activity of the reticular formation and hypothalamus, etc. Hormones affect behavior, motivation and reflexes, and are involved in the stress response.

There are reflexes in which the hormonal part is included as a link. For example: cold - receptor - CNS - hypothalamus - releasing factor - secretion of thyroid-stimulating hormone - thyroxine - increase in cell metabolism - increase in body temperature.

Methods for studying the endocrine glands.

1. Removal of the gland - extirpation.

2. Transplantation of the gland, the introduction of the extract.

3. Chemical blockade of gland functions.

4. Determination of hormones in liquid media.

5. Method of radioactive isotopes.

3. Mechanisms of interaction of hormones with cells. The concept of target cells. Types of hormone reception by target cells. The concept of membrane and cytosolic receptors.

Peptide (protein) hormones are produced in the form of prohormones (their activation occurs during hydrolytic cleavage), water soluble hormones accumulate in cells in the form of granules, fat-soluble (steroids) - are released as they form.

For hormones in the blood, there are carrier proteins - these are transport proteins that can bind hormones. In this case, no chemical reactions take place. Part of the hormones can be transferred in dissolved form. Hormones are delivered to all tissues, but only cells that have receptors for the action of the hormone react to the action of hormones. Cells that carry receptors are called target cells. Target cells are divided into: hormone-dependent and

hormone-sensitive.

The difference between these two groups is that hormone-dependent cells can only develop in the presence of this hormone. (So, for example, sex cells can develop only in the presence of sex hormones), and hormone-sensitive cells can develop without a hormone, but they are able to perceive the action of these hormones. (So, for example, the cells of the nervous system develop without the influence of sex hormones, but perceive their action).

Each target cell has a specific receptor for the action of the hormone, and some of the receptors are located in the membrane. This receptor is stereospecific. In other cells, receptors are located in the cytoplasm - these are cytosolic receptors that react with the hormone that enters the cell.

Therefore, receptors are divided into membrane and cytosolic. In order for the cell to respond to the action of the hormone, the formation of secondary messengers for the action of hormones is necessary. This is typical for hormones with a membrane type of reception.

4. Systems of secondary mediators of action of peptide hormones and catecholamines.

Secondary mediators of hormone action are:

1. Adenylate cyclase and cyclic AMP,

2. Guanylate cyclase and cyclic GMF,

3. Phospholipase C:

diacylglycerol (DAG),

Inositol-tri-fsphate (IF3),

4. Ionized Ca - calmodulin

Heterotrophic protein G-protein.

This protein forms loops in the membrane and has 7 segments. They are compared with serpentine ribbons. It has a protruding (outer) and inner part. A hormone is attached to the outer part, and on the inner surface there are 3 subunits - alpha, beta and gamma. In an inactive state, this protein has guanosine diphosphate. But when activated, guanosine diphosphate changes to guanosine triphosphate. A change in the activity of the G-protein leads either to a change in the ionic permeability of the membrane, or the enzyme system (adenylate cyclase, guanylate cyclase, phospholipase C) is activated in the cell. This causes the formation of specific proteins, protein kinase is activated (required for phosphorylation processes).

G-proteins can be activating (Gs) and inhibitory, or in other words, inhibitory (Gi).

The destruction of cyclic AMP occurs under the action of the enzyme phosphodiesterase. Cyclic HMF has the opposite effect. When phospholipase C is activated, substances are formed that contribute to the accumulation of ionized calcium inside the cell. Calcium activates protein cinases, promotes muscle contraction. Diacylglycerol promotes the conversion of membrane phospholipids into arachidonic acid, which is the source of the formation of prostaglandins and leukotrienes.

The hormone receptor complex penetrates the nucleus and acts on DNA, which changes the transcription processes and mRNA is formed, which leaves the nucleus and goes to the ribosomes.

Therefore, hormones can provide:

1. Kinetic or starting action,

2. Metabolic action,

3. Morphogenetic action (tissue differentiation, growth, metamorphosis),

4. Corrective action (corrective, adaptive).

Mechanisms of action of hormones in cells:

Changes in the permeability of cell membranes,

Activation or inhibition of enzyme systems,

Influence on genetic information.

Regulation is based on the close interaction of the endocrine and nervous systems. The processes of excitation in the nervous system can activate or inhibit the activity of the endocrine glands. (Consider, for example, the process of ovulation in a rabbit. Ovulation in a rabbit occurs only after the act of mating, which stimulates the release of gonadotropic hormone from the pituitary gland. The latter causes the process of ovulation).

After the transfer of mental trauma, thyrotoxicosis may occur. The nervous system controls the secretion of pituitary hormones (neurohormone), and the pituitary gland influences the activity of other glands.

There are feedback mechanisms. The accumulation of a hormone in the body leads to inhibition of the production of this hormone by the corresponding gland, and the deficiency will be a mechanism for stimulating the formation of the hormone.

There is a self-regulation mechanism. (For example, blood glucose determines the production of insulin and/or glucagon; if the sugar level rises, insulin is produced, and if it falls, glucagon is produced. A lack of Na stimulates the production of aldosterone.)

6. Adenohypophysis, its connection with the hypothalamus. The nature of the action of the hormones of the anterior pituitary gland. Hypo- and hypersecretion of adenohypophysis hormones. Age-related changes in the formation of hormones of the anterior lobe.

Cells of the adenohypophysis (see their structure and composition in the course of histology) produce the following hormones: somatotropin (growth hormone), prolactin, thyrotropin (thyroid-stimulating hormone), follicle-stimulating hormone, luteinizing hormone, corticotropin (ACTH), melanotropin, beta-endorphin, diabetogenic peptide, exophthalmic factor and ovarian growth hormone. Let us consider in more detail the effects of some of them.

Corticotropin . (adrenocorticotropic hormone - ACTH) is secreted by the adenohypophysis in continuously pulsating bursts that have a clear daily rhythm. The secretion of corticotropin is regulated by direct and feedback. The direct connection is represented by the hypothalamus peptide - corticoliberin, which enhances the synthesis and secretion of corticotropin. Feedbacks are triggered by blood levels of cortisol (hormone of the adrenal cortex) and are closed both at the level of the hypothalamus and adenohypophysis, and an increase in cortisol concentration inhibits the secretion of corticoliberin and corticotropin.

Corticotropin has two types of action - adrenal and extra-adrenal. The adrenal action is the main one and consists in stimulating the secretion of glucocorticoids, to a much lesser extent - mineralocorticoids and androgens. The hormone enhances the synthesis of hormones in the adrenal cortex - steroidogenesis and protein synthesis, leading to hypertrophy and hyperplasia of the adrenal cortex. Extra-adrenal action consists in lipolysis of adipose tissue, increased secretion of insulin, hypoglycemia, increased deposition of melanin with hyperpigmentation.

An excess of corticotropin is accompanied by the development of hypercortisolism with a predominant increase in cortisol secretion and is called Itsenko-Cushing's disease. The main manifestations are typical for an excess of glucocorticoids: obesity and other metabolic changes, a decrease in the effectiveness of immunity mechanisms, the development of arterial hypertension and the possibility of diabetes. Corticotropin deficiency causes insufficiency of the glucocorticoid function of the adrenal glands with pronounced metabolic changes, as well as a decrease in the body's resistance to adverse environmental conditions.

Somatotropin . . Growth hormone has a wide range of metabolic effects that provide a morphogenetic effect. The hormone affects protein metabolism, enhancing anabolic processes. It stimulates the entry of amino acids into cells, protein synthesis by accelerating translation and activating RNA synthesis, increases cell division and tissue growth, and inhibits proteolytic enzymes. Stimulates the incorporation of sulfate into cartilage, thymidine into DNA, proline into collagen, uridine into RNA. The hormone causes a positive nitrogen balance. Stimulates the growth of epiphyseal cartilage and their replacement by bone tissue by activating alkaline phosphatase.

The effect on carbohydrate metabolism is twofold. On the one hand, somatotropin increases insulin production, both due to a direct effect on beta cells, and due to hormone-induced hyperglycemia due to the breakdown of glycogen in the liver and muscles. Somatotropin activates liver insulinase, an enzyme that breaks down insulin. On the other hand, somatotropin has a counter-insular effect, inhibiting the utilization of glucose in tissues. This combination of effects, when predisposed under conditions of excessive secretion, can cause diabetes mellitus, called pituitary in origin.

The effect on fat metabolism is to stimulate lipolysis of adipose tissue and the lipolytic effect of catecholamines, increase the level of free fatty acids in the blood; due to their excessive intake in the liver and oxidation, the formation of ketone bodies increases. These effects of somatotropin are also classified as diabetogenic.

If an excess of the hormone occurs in early age, gigantism is formed with a proportional development of the limbs and torso. Excess hormone in adolescence and adulthood causes an increase in the growth of the epiphyseal parts of the bones of the skeleton, zones with incomplete ossification, which is called acromegaly. . Increase in size and internal organs - splanhomegaly.

With a congenital deficiency of the hormone, dwarfism is formed, called "pituitary nanism". After the publication of J. Swift's novel about Gulliver, such people are colloquially called Lilliputians. In other cases, acquired hormone deficiency causes a mild stunting.

Prolactin . The secretion of prolactin is regulated by hypothalamic peptides - the inhibitor prolactinostatin and the stimulator prolactoliberin. The production of hypothalamic neuropeptides is under dopaminergic control. The level of estrogen and glucocorticoids in the blood affects the amount of prolactin secretion.

and thyroid hormones.

Prolactin specifically stimulates mammary gland development and lactation, but not its secretion, which is stimulated by oxytocin.

In addition to the mammary glands, prolactin affects the sex glands, helping to maintain the secretory activity of the corpus luteum and the formation of progesterone. Prolactin is a regulator of water-salt metabolism, reducing the excretion of water and electrolytes, potentiates the effects of vasopressin and aldosterone, stimulates the growth of internal organs, erythropoiesis, and promotes the manifestation of motherhood. In addition to enhancing protein synthesis, it increases the formation of fat from carbohydrates, contributing to postpartum obesity.

Melanotropin . . Formed in the cells of the intermediate lobe of the pituitary gland. The production of melanotropin is regulated by melanoliberin of the hypothalamus. The main effect of the hormone is to act on melanocytes of the skin, where it causes depression of the pigment in the processes, an increase in free pigment in the epidermis surrounding melanocytes, and an increase in melanin synthesis. Increases skin and hair pigmentation.

7. Neurohypophysis, its connection with the hypothalamus. Effects of posterior pituitary hormones (oxygocin, ADH). The role of ADH in the regulation of fluid volume in the body. Non-sugar diabetes.

Vasopressin . . It is formed in the cells of the supraoptic and paraventricular nuclei of the hypothalamus and accumulates in the neurohypophysis. The main stimuli regulating the synthesis of vasopressin in the hypothalamus and its secretion into the blood by the pituitary gland can generally be called osmotic. They are represented by: a) an increase in the osmotic pressure of blood plasma and stimulation of osmoreceptors of blood vessels and neurons-osmoreceptors of the hypothalamus; b) an increase in the sodium content in the blood and stimulation of hypothalamic neurons that act as sodium receptors; c) a decrease in the central volume of circulating blood and arterial pressure, perceived by the volomoreceptors of the heart and mechanoreceptors of the vessels;

d) emotional and painful stress and physical activity; e) activation of the renin-angiotensin system and the stimulating effect of angiotensin on neurosecretory neurons.

The effects of vasopressin are realized by binding the hormone in tissues with two types of receptors. Binding to Y1-type receptors, predominantly located in the wall of blood vessels, through the second messengers inositol triphosphate and calcium causes vascular spasm, which contributes to the name of the hormone - "vasopressin". Binding to Y2-type receptors in the distal nephron through secondary intermediary cAMP provides an increase in the permeability of the collecting ducts of the nephron for water, its reabsorption and concentration of urine, which corresponds to the second name of vasopressin - "antidiuretic hormone, ADH".

In addition to acting on the kidney and blood vessels, vasopressin is one of the important brain neuropeptides involved in the formation of thirst and drinking behavior, memory mechanisms, and regulation of the secretion of adenohypophyseal hormones.

deficiency or even complete absence secretion of vasopressin manifests itself in the form of a sharp increase in diuresis with the release a large number hypotonic urine. This syndrome is called diabetes insipidus ", it can be congenital or acquired. The syndrome of excess vasopressin (Parchon's syndrome) manifests itself

in excessive fluid retention in the body.

Oxytocin . The synthesis of oxytocin in the paraventricular nuclei of the hypothalamus and its release into the blood from the neurohypophysis is stimulated by a reflex pathway upon stimulation of the stretch receptors of the cervix and mammary gland receptors. Estrogens increase the secretion of oxytocin.

Oxytocin causes the following effects: a) stimulates the contraction of the smooth muscles of the uterus, contributing to childbirth; b) causes contraction of the smooth muscle cells of the excretory ducts of the lactating mammary gland, ensuring the release of milk; c) under certain conditions, it has a diuretic and natriuretic effect; d) participates in the organization of drinking and eating behavior; e) is an additional factor in the regulation of the secretion of adenohypophyseal hormones.

8. Adrenal cortex. Hormones of the adrenal cortex and their function. Regulation of corticosteroid secretion. Hypo- and hyperfunction of the adrenal cortex.

Mineralocorticoids are secreted in the zona glomeruli of the adrenal cortex. The main mineralocorticoid is aldosterone .. This hormone is involved in the regulation of the exchange of salts and water between the internal and external environment, mainly affecting the tubular apparatus of the kidneys, as well as sweat and salivary glands, intestinal mucosa. acting on cell membranes vasculature and tissues, the hormone also regulates the exchange of sodium, potassium and water between the extracellular and intracellular environment.

The main effects of aldosterone in the kidneys are an increase in sodium reabsorption in the distal tubules with its retention in the body and an increase in potassium excretion in the urine with a decrease in the cation content in the body. Under the influence of aldosterone, there is a delay in the body of chlorides, water, increased excretion of hydrogen ions, ammonium, calcium and magnesium. The volume of circulating blood increases, a shift is formed acid-base balance towards alkalosis. Aldosterone can have a glucocorticoid effect, but it is 3 times weaker than that of cortisol and does not manifest itself under physiological conditions.

Mineralocorticoids are vital hormones, since the death of the body after removal of the adrenal glands can be prevented by introducing hormones from outside. Mineralocorticoids increase inflammation, which is why they are sometimes called anti-inflammatory hormones.

The main regulator of the formation and secretion of aldosterone is angiotensin II, which made it possible to consider aldosterone as part of renin-angiotensin-aldosterone system (RAAS), providing regulation of water-salt and hemodynamic homeostasis. The feedback link in the regulation of aldosterone secretion is realized when the level of potassium and sodium in the blood changes, as well as the volume of blood and extracellular fluid, and the sodium content in the urine of the distal tubules.

Excess production of aldosterone - aldosteronism - can be primary and secondary. In primary aldosteronism, the adrenal gland, due to hyperplasia or a tumor of the glomerular zone (Kon's syndrome), produces increased amounts of the hormone, which leads to a delay in the body of sodium, water, edema and arterial hypertension, loss of potassium and hydrogen ions through the kidneys, alkalosis and shifts in myocardial excitability and nervous system. Secondary aldosteronism is the result of excess production of angiotensin-II and increased stimulation of the adrenal glands.

The lack of aldosterone in case of damage to the adrenal gland by a pathological process is rarely isolated, more often combined with a deficiency of other hormones of the cortical substance. Leading disorders are observed in the cardiovascular and nervous systems, which is associated with inhibition of excitability,

a decrease in BCC and shifts in the electrolyte balance.

Glucocorticoids (cortisol and corticosterone ) affect all types of exchange.

Hormones have mainly catabolic and antianabolic effects on protein metabolism, causing a negative nitrogen balance. protein breakdown occurs in muscle, connective bone tissue, the level of albumin in the blood will fall. The permeability of cell membranes for amino acids decreases.

The effects of cortisol on fat metabolism are due to a combination of direct and indirect influences. The synthesis of fat from carbohydrates by cortisol itself is suppressed, but due to hyperglycemia caused by glucocorticoids and increased insulin secretion, fat formation is increased. Fat is deposited in

upper body, neck and face.

The effects on carbohydrate metabolism are generally opposite to those of insulin, which is why glucocorticoids are called contra-insular hormones. Under the influence of cortisol, hyperglycemia occurs due to: 1) increased formation of carbohydrates from amino acids by gluconeogenesis; 2) suppression of glucose utilization by tissues. Hyperglycemia results in glucosuria and stimulation of insulin secretion. A decrease in the sensitivity of cells to insulin, together with contra-insular and catabolic effects, can lead to the development of steroid diabetes mellitus.

The systemic effects of cortisol are manifested in the form of a decrease in the number of lymphocytes, eosinophils and basophils in the blood, an increase in neutrophils and erythrocytes, an increase in sensory sensitivity and excitability of the nervous system, an increase in the sensitivity of adrenergic receptors to the action of catecholamines, maintaining an optimal functional state and regulation of the heart vascular system. Glucocorticoids increase the body's resistance to the action of excessive stimuli and suppress inflammation and allergic reactions, which is why they are called adaptive and anti-inflammatory hormones.

Excess glucocorticoids, not associated with increased secretion of corticotropin, is called Itsenko-Cushing's syndrome. Its main manifestations are similar to Itsenko-Cushing's disease, however, due to feedback, the secretion of corticotropin and its level in the blood are significantly reduced. Muscle weakness, a tendency to diabetes, hypertension and disorders of the genital area, lymphopenia, peptic ulcers of the stomach, changes in the psyche - this is not a complete list of symptoms of hypercortisolism.

Glucocorticoid deficiency causes hypoglycemia, reduced body resistance, neutropenia, eosinophilia and lymphocytosis, impaired adrenoreactivity and heart activity, and hypotension.

9. Sympathetic-adrenal system, its functional organization. Catecholamines as mediators and hormones. Participation in stress. Nervous regulation of chromaffin tissue of the adrenal glands.

Catecholamines - hormones of the adrenal medulla epinephrine and norepinephrine , which are secreted in a ratio of 6:1.

major metabolic effects. adrenaline are: increased breakdown of glycogen in the liver and muscles (glycogenolysis) due to the activation of phosphorylase, suppression of glycogen synthesis, suppression of glucose consumption by tissues, hyperglycemia, increased oxygen consumption by tissues and oxidative processes in them, activation of the breakdown and mobilization of fat and its oxidation.

Functional effects of catecholamines. depend on the predominance of one of the types of adrenergic receptors (alpha or beta) in the tissues. For adrenaline, the main functional effects are manifested in the form of: increased and increased heart rate, improved conduction of excitation in the heart, vasoconstriction of the skin and organs abdominal cavity; increase in heat generation in tissues, weakening of contractions of the stomach and intestines, relaxation of bronchial muscles, dilation of pupils, reduction glomerular filtration and urine formation, stimulation of renin secretion by the kidney. Thus, adrenaline causes an improvement in the interaction of the body with the external environment, increases efficiency in emergency conditions. Adrenaline is a hormone of urgent (emergency) adaptation.

The release of catecholamines is regulated by the nervous system through sympathetic fibers passing through the celiac nerve. The nerve centers that regulate the secretory function of chromaffin tissue are located in the hypothalamus.

10. Endocrine function of the pancreas. Mechanisms of action of its hormones on carbohydrate, fat, protein metabolism. Regulation of glucose content in the liver, muscle tissue, nerve cells. Diabetes. Hyperinsulinemia.

Sugar-regulating hormones, i.e. Many endocrine gland hormones affect blood sugar and carbohydrate metabolism. But the hormones of the islets of Langerhans of the pancreas have the most pronounced and powerful effects - insulin and glucagon . The first of them can be called hypoglycemic, as it lowers the level of sugar in the blood, and the second - hyperglycemic.

Insulin has a powerful effect on all types of metabolism. Its effect on carbohydrate metabolism is mainly manifested by the following effects: it increases the permeability of cell membranes in muscles and adipose tissue for glucose, activates and increases the content of enzymes in cells, enhances glucose utilization by cells, activates phosphorylation processes, inhibits the breakdown and stimulates glycogen synthesis, inhibits gluconeogenesis activates glycolysis.

The main effects of insulin on protein metabolism: increased membrane permeability for amino acids, increased synthesis of proteins necessary for the formation

nucleic acids, primarily mRNA, activation of amino acid synthesis in the liver, activation of synthesis and suppression of protein breakdown.

The main effects of insulin on fat metabolism: stimulation of the synthesis of free fatty acids from glucose, stimulation of the synthesis of triglycerides, suppression of fat breakdown, activation of the oxidation of ketone bodies in the liver.

Glucagon causes the following main effects: activates glycogenolysis in the liver and muscles, causes hyperglycemia, activates gluconeogenesis, lipolysis and suppression of fat synthesis, increases the synthesis of ketone bodies in the liver, stimulates protein catabolism in the liver, increases urea synthesis.

The main regulator of insulin secretion is D-glucose in the incoming blood, which activates a specific cAMP pool in beta cells and, through this mediator, leads to stimulation of insulin release from secretory granules. It enhances the response of beta cells to the action of glucose, the intestinal hormone - gastric inhibitory peptide (GIP). Through a non-specific, glucose-independent pool, cAMP stimulates insulin secretion and CA++ ions. The nervous system also plays a role in the regulation of insulin secretion, in particular, the vagus nerve and acetylcholine stimulate insulin secretion, while sympathetic nerves and catecholamines inhibit insulin secretion and stimulate glucagon secretion through alpha-adrenergic receptors.

A specific inhibitor of insulin production is the hormone of the delta cells of the islets of Langerhans. - somatostatin . This hormone is also produced in the intestines, where it inhibits glucose absorption and thereby reduces the response of beta cells to a glucose stimulus.

Glucagon secretion is stimulated with a decrease in blood glucose levels, under the influence of gastrointestinal hormones (GIP, gastrin, secretin, pancreozymin-cholecystokinin) and with a decrease in the content of CA ++ ions, and is inhibited by insulin, somatostatin, glucose and calcium.

An absolute or relative lack of insulin in relation to glucagon manifests itself in the form of diabetes mellitus. In this disease, profound metabolic disorders occur and, if insulin activity is not artificially restored from the outside, death may occur. Diabetes mellitus is characterized by hypoglycemia, glucosuria, polyuria, thirst, constant feeling hunger, ketonemia, acidosis, weak immunity, circulatory failure and many other disorders. An extremely severe manifestation of diabetes is diabetic coma.

11. Thyroid gland, physiological role her hormones. Hypo- and hyperfunction.

Thyroid hormones are triiodothyronine and tetraiodothyronine (thyroxine ). The main regulator of their release is the adenohypophysis hormone thyrotropin. In addition, there is a direct nervous regulation of the thyroid gland through sympathetic nerves. Feedback is provided by the level of hormones in the blood and is closed both in the hypothalamus and in the pituitary gland. The intensity of secretion of thyroid hormones affects the volume of their synthesis in the gland itself (local feedback).

major metabolic effects. thyroid hormones are: increased oxygen uptake by cells and mitochondria, activation of oxidative processes and an increase in basal metabolism, stimulation of protein synthesis by increasing the permeability of cell membranes for amino acids and activation of the genetic apparatus of the cell, lipolytic effect, activation of the synthesis and excretion of cholesterol with bile, activation of glycogen breakdown , hyperglycemia, increased glucose consumption by tissues, increased absorption of glucose in the intestine, activation of liver insulinase and acceleration of insulin inactivation, stimulation of insulin secretion due to hyperglycemia.

The main functional effects of thyroid hormones are: providing normal processes growth, development and differentiation of tissues and organs, activation of sympathetic effects due to a decrease in the breakdown of the mediator, the formation of catecholamine-like metabolites and an increase in the sensitivity of adrenoreceptors (tachycardia, sweating, vasospasm, etc.), an increase in heat production and body temperature, activation of IRR and increased excitability of the central nervous system, increase in the energy efficiency of mitochondria and myocardial contractility, a protective effect in relation to the development of myocardial damage and ulceration in the stomach under stress, an increase in renal blood flow, glomerular filtration and diuresis, stimulation of regeneration and healing processes, ensuring normal reproductive activity.

Increased secretion of thyroid hormones is a manifestation of hyperfunction of the thyroid gland - hyperthyroidism. At the same time, characteristic changes in metabolism are noted (increased basal metabolism, hyperglycemia, weight loss, etc.), symptoms of excess sympathetic effects (tachycardia, increased sweating, increased excitability, increased blood pressure, etc.). Maybe

develop diabetes.

Congenital deficiency of thyroid hormones disrupts the growth, development and differentiation of the skeleton, tissues and organs, including the nervous system (mental retardation occurs). This congenital pathology called "cretinism". Acquired insufficiency of the thyroid gland or hypothyroidism manifests itself in a slowdown in oxidative processes, a decrease in basal metabolism, hypoglycemia, degeneration of subcutaneous fat and skin with the accumulation of glycosaminoglycans and water. The excitability of the central nervous system decreases, sympathetic effects and heat production are weakened. The complex of such violations is called "myxedema", i.e. mucous swelling.

Calcitonin - produced in parafollicular K-cells of the thyroid gland. Target organs for calcitonin are bones, kidneys and intestines. Calcitonin lowers blood calcium levels by facilitating mineralization and inhibiting bone resorption. Reduces the reabsorption of calcium and phosphate in the kidneys. Calcitonin inhibits the secretion of gastrin in the stomach and reduces the acidity of gastric juice. The secretion of calcitonin is stimulated by an increase in the level of Ca ++ in the blood and by gastrin.

12. Parathyroid glands, their physiological role. Maintenance mechanisms

concentrations of calcium and phosphate in the blood. The value of vitamin D.

The regulation of calcium metabolism is carried out mainly due to the action of parathyrin and calcitonin. Parathormone, or parathyrin, parathyroid hormone is synthesized in the parathyroid glands. It provides an increase in the level of calcium in the blood. The target organs for this hormone are the bones and kidneys. In bone tissue, para-thyrin enhances the function of osteoclasts, which contributes to bone demineralization and an increase in the level of calcium and phosphorus in the blood plasma. In the tubular apparatus of the kidneys, parathyrin stimulates calcium reabsorption and inhibits phosphate reabsorption, leading to hypercalcemia and phosphaturia. The development of phosphaturia may be of some importance in the implementation of the hypercalcemic effect of the hormone. This is due to the fact that calcium forms insoluble compounds with phosphates; therefore, increased excretion of phosphates in the urine contributes to an increase in the level of free calcium in the blood plasma. Parathyrin enhances the synthesis of calcitriol, which is an active metabolite of vitamin D 3 . The latter is first formed in an inactive state in the skin under the influence of ultraviolet radiation, and then under the influence of parathyrin, it is activated in the liver and kidneys. Calcitriol enhances the formation of calcium-binding protein in the intestinal wall, which promotes calcium reabsorption and the development of hypercalcemia. Thus, an increase in calcium reabsorption in the intestine during hyperproduction of parathyrin is mainly due to its stimulating effect on the activation of vitamin D 3 . The direct effect of parathyrin itself on the intestinal wall is very insignificant.

When the parathyroid glands are removed, the animal dies from tetanic convulsions. This is due to the fact that in the case low content calcium in the blood sharply increases neuromuscular excitability. At the same time, the action of even insignificant external stimuli leads to muscle contraction.

Hyperproduction of parathyrin leads to demineralization and resorption of bone tissue, the development of osteoporosis. The level of calcium in the blood plasma increases sharply, as a result of which the tendency to stone formation in the organs increases genitourinary system. Hypercalcemia contributes to the development of severe disturbances in the electrical stability of the heart, as well as the formation of ulcers in digestive tract, the occurrence of which is due to the stimulating effect of Ca 2+ ions on the production of gastrin and hydrochloric acid in the stomach.

The secretion of parathyrin and thyrocalcitonin (see section 5.2.3) is regulated by the type of negative feedback depending on the level of calcium in the blood plasma. With a decrease in the calcium content, the secretion of parathyrin increases and the production of thyrocalcitonin is inhibited. Under physiological conditions, this can be observed during pregnancy, lactation, reduced calcium content in the food taken. An increase in the concentration of calcium in the blood plasma, on the contrary, helps to reduce the secretion of parathyrin and increase the production of thyrocalcitonin. The latter can be of great importance in children and young people, since at this age the formation of the bone skeleton is carried out. An adequate course of these processes is impossible without thyrocalcitonin, which determines the absorption of calcium from the blood plasma and its inclusion in the structure of bone tissue.

13. Sex glands. Functions of female sex hormones. Menstrual-ovarian cycle, its mechanism. Fertilization, pregnancy, childbirth, lactation. Endocrine regulation of these processes. Age-related changes in hormone production.

male sex hormones .

Male sex hormones - androgens - formed in the Leydig cells of the testes from cholesterol. The main human androgen is testosterone . . Small amounts of androgens are produced in the adrenal cortex.

Testosterone has a wide range of metabolic and physiological effects: ensuring the processes of differentiation in embryogenesis and the development of primary and secondary sexual characteristics, the formation of CNS structures that ensure sexual behavior and sexual functions, a generalized anabolic effect that ensures the growth of the skeleton and muscles, the distribution of subcutaneous fat, the provision of spermatogenesis, retention of nitrogen, potassium, phosphate in the body, activation of RNA synthesis, stimulation of erythropoiesis.

Androgens are also formed in small amounts in the female body, being not only the precursors of estrogen synthesis, but also supporting sexual desire, as well as stimulating the growth of pubic and armpit hair.

female sex hormones .

The secretion of these hormones estrogen) is closely related to the female reproductive cycle. The female sexual cycle provides a clear integration over time of the various processes necessary for the implementation reproductive function- periodic preparation of the endometrium for embryo implantation, egg maturation and ovulation, changes in secondary sexual characteristics, etc. Coordination of these processes is provided by fluctuations in the secretion of a number of hormones, primarily gonadotropins and sex steroids. The secretion of gonadotropins is carried out as "tonically", i.e. continuously, and "cyclically", with periodic release of large amounts of folliculin and luteotropin in the middle of the cycle.

The sexual cycle lasts 27-28 days and is divided into four periods:

1) preovulatory - the period of preparation for pregnancy, the uterus at this time increases in size, the mucous membrane and its glands grow, the contraction of the fallopian tubes and the muscular layer of the uterus intensifies and becomes more frequent, the mucous membrane of the vagina also grows;

2) ovulatory- begins with the rupture of the vesicular ovarian follicle, the release of the egg from it and its advancement through the fallopian tube into the uterine cavity. During this period, fertilization usually occurs, the sexual cycle is interrupted and pregnancy occurs;

3) post-ovulation- in women during this period, menstruation appears, an unfertilized egg, which remains alive in the uterus for several days, dies, tonic contractions of the muscles of the uterus increase, leading to the rejection of its mucous membrane and the release of scraps of mucous along with blood.

4) rest period- occurs after the end of the post-ovulation period.

Hormonal shifts during the sexual cycle are accompanied by the following rearrangements. Before ovulation period first, there is a gradual increase in the secretion of follitropin by the adenohypophysis. The maturing follicle produces an increasing amount of estrogens, which, in feedback, begins to reduce the production of follinotropin. The rising level of lutropin leads to stimulation of the synthesis of enzymes, leading to thinning of the follicle wall, necessary for ovulation.

In the ovulation period, there is a sharp surge in blood levels of lutropin, follitropin and estrogen.

In the initial phase of the postovulation period, there is a short-term drop in the level of gonadotropins and estradiol , the ruptured follicle begins to fill with luteal cells, new blood vessels form. Increasing production progesterone formed by the corpus luteum, the secretion of estradiol by other maturing follicles increases. The resulting level of progesterone and estrogen in feedback inhibits the secretion of follotropin and luteotropin. The degeneration of the corpus luteum begins, the level of progesterone and estrogens in the blood falls. In the secretory epithelium without steroid stimulation, hemorrhagic and degenerative changes, which leads to bleeding, mucosal rejection, uterine contraction, i.e. to menstruation.

14. Functions of male sex hormones. regulation of their education. Pre- and postnatal effects of sex hormones on the body. Age-related changes in hormone production.

Endocrine function of the testicles.

1) Sertolli cells - produce the hormone-inhibin - inhibits the formation of follitropin in the pituitary gland, the formation and secretion of estrogens.

2) Leydig cells - produce the hormone testosterone.

1. Provides processes of differentiation in embryogenesis
2. Development of primary and secondary sexual characteristics
3. Formation of CNS structures that provide sexual behavior and functions
4. Anabolic action (growth of the skeleton, muscles, distribution of subcutaneous fat)
5. Regulation of spermatogenesis
6. Retains nitrogen, potassium, phosphate, calcium in the body
7. Activates RNA synthesis
8. Stimulates erythropoiesis.

Endocrine function of the ovaries.

In the female body, hormones are produced in the ovaries and hormonal function possess cells of the granular layer of the follicles that produce estrogens (estradiol, estrone, estriol) and corpus luteum cells (produce progesterone).

Functions of estrogen:

1. Provide sexual differentiation in embryogenesis.
2. Puberty and the development of female sexual characteristics
3. Establishment of the female sexual cycle, growth of the muscles of the uterus, development of the mammary glands
4. Determine sexual behavior, oogenesis, fertilization and implantation in eggs
5. Development and differentiation of the fetus and the course of the birth act
6. Suppress bone resorption, retain nitrogen, water, salts in the body

Functions of Progesterone:

1. Suppresses uterine muscle contraction

2. Needed for ovulation

3. Suppresses the secretion of gonadotropin

4. It has an anti-aldosterone effect, that is, it stimulates natriuresis.

15. Thymus gland (thymus), its physiological role.

The thymus gland is also called the thymus or thymus gland. It, like the bone marrow, is the central organ of immunogenesis (the formation of immunity). The thymus is located directly behind the sternum and consists of two lobes (right and left), connected loose fiber. The thymus is formed earlier than other organs of the immune system, its mass in newborns is 13 g, the largest mass - about 30 g - the thymus has in children 6-15 years old.

Then he undergoes reverse development(age involution) and in adults is almost completely replaced by adipose tissue (in people over 50 years of age, adipose tissue is 90% of total weight thymus (average 13-15 gr.)). The period of the most intensive growth of the organism is associated with the activity of the thymus. The thymus contains small lymphocytes (thymocytes). The decisive role of the thymus in the formation of the immune system became clear from the experiments conducted by the Australian scientist D. Miller in 1961.

He found that removing the thymus from newborn mice resulted in reduced antibody production and increased lifespan of the transplanted tissue. These facts indicated that the thymus takes part in two forms of the immune response: in reactions humoral type- the production of antibodies and in reactions cell type- rejection (death) of transplanted foreign tissue (graft), which occur with the participation different classes lymphocytes. The so-called B-lymphocytes are responsible for the production of antibodies, and T-lymphocytes are responsible for transplant rejection reactions. T- and B-lymphocytes are formed by various transformations of stem cells bone marrow.

Penetrating from it into the thymus, the stem cell is transformed under the influence of the hormones of this organ, first into the so-called thymocyte, and then, getting into the spleen or The lymph nodes, - into an immunologically active T-lymphocyte. The transformation of a stem cell into a B-lymphocyte occurs, apparently, in the bone marrow. In the thymus, along with the formation of T-lymphocytes from bone marrow stem cells, hormonal factors - thymosin and thymopoietin - are produced.

Hormones that provide differentiation (difference) of T-lymphocytes and play a role in cellular immune responses. There is also evidence that hormones provide the synthesis (construction) of some cell receptors.

Endocrine glands are also referred to as endocrine or endocrine glands. Endocrine glands secrete hormones. The glands owe their name to the absence of excretory ducts. The active substances produced by them begin to be released into the blood.

Human endocrine glands include:

• Adrenals.
• Pancreas.
• Hypothalamic-pituitary system.
• thymus.
• epiphysis
• Sex glands.

Short description

The following table gives a general description of what are called endocrine glands.

Name	Description
Pituitary	It is the main gland. Provides the release of hormones that regulate the activity of other glands.
adrenal glands	Cortical and medulla are different concepts.
parathyroid glands	Humans have 4 parathyroid glands.
Endocrine part of the pancreas	Its cells make up no more than 1 percent of total number. The rest of the cells perform the function of the glands of external secretion.
thymus	Performs the functions of an organ of immunity.
Endocrine part of the gonads	In women, these are the ovaries; in men, the testes.
Placenta	Shows activity during gestation.

Features of the hypothalamus

In its anatomical nature, it does not belong to the endocrine glands. It includes nerve cells that synthesize hormones into the blood.

Nuclear formations of the hypothalamic region are involved in maintaining normal temperature body. The preoptic zone contains neurons responsible for monitoring blood temperature.

Other functions of the hypothalamus should also be listed:

• regulation of the functions of the cardiac system;
• regulation of the functions of the vascular system;
• regulation of water balance;
• regulation of contractile activity of the uterus;
• regulation of behavioral activity;
• creating feelings of hunger and satiety.

The most common lesion of the hypothalamus is prolactinoma. Most often it occurs in women. With this hormonally active tumor begins to be produced. Another formidable pathology is diagnosed in people of both sexes.

Features of the pituitary gland

small gland, whose mass varies from 0.5 to 0.7 grams, is called. It is located in the pituitary fossa of the Turkish saddle of the sphenoid bone. This hormone consists of the anterior, intermediate and posterior lobes.

The anterior lobe secretes the following substances:

• Somatotropic.
• Gonadotropic.

Somatotropic hormone plays an important role in metabolic processes, as well as controlling muscle, bone growth. A thyroid stimulant is meant to control the thyroid gland. Adrenocorticotropic substance controls the work of the adrenal cortex.

Pituitary deficiency leads to. Doctors believe that such a disease is no less dangerous than diabetes. Excess leads to disruption of menstruation in women and impotence in men.

Features of the endocrine thyroid organ

A huge role in the human body is played by the endocrine thyroid organ, which contributes to the release of the following iodine-containing:

• thyroxine;
• terocalcitonin;
• triiodothyronine.

The substances produced by it control phosphorus, calcium metabolism, as well as the level of energy costs, most of which are necessary for the body. Parathyroid glands secrete hormones that increase the calcium, phosphorus content in the blood.

The normal functioning of the "thyroid gland", as well as its productivity, is carried out due to the regular intake of 200 micrograms of iodine into the body. People get it with food, liquid, air. Underfunction of the gland can lead to hypothyroidism. Neuroses often occur in young women with insufficient thyroid function. obsessive states. Many girls develop depression against this background.

Deficiency adversely affects the state of the vascular and cardiac systems. The normal functioning of the heart is disrupted, and against this background, heart failure develops. 30% of patients have decreased blood pressure.

Features of the adrenal glands

Hormones in the adrenal glands produce cortex and medulla. In the cortical substance, the synthesis of corticosteroids is carried out. In addition, hormones are produced by the following zones:

• glomerular;
• beam;
• mesh.

In the glomerular zone, not only the production of mineralocorticoids, deoxycorticosterone, but also their mineral metabolism is controlled. In the beam zone, the production of glucocorticoids, cortisol and corticosterone is carried out. It also controls the metabolism of fats, carbohydrates and proteins.

Androgens and sex hormones are produced in the reticular zone. The medulla is the supplier of and. Adrenaline is responsible for positive emotions. Norepinephrine controls the nervous processes.

Features of the pancreas

Among the mixed glands physicians include the pancreas. It is located in the abdominal cavity, at the level of the bodies of one or two lumbar vertebrae behind the stomach.

From the stomach, iron is protected by a stuffing bag. Average weight glands of an adult varies from eighty to one hundred grams. Length ranges from fourteen to eighteen, thickness - from two to three, width - from three to nine centimeters.

This gland performs an ambiguous function. Its certain cells produce digestive juice. It enters the intestine through the excretory ducts. Other cells are involved in the production of insulin, which is responsible for the conversion of excess glucose into glycogen. This helps to lower blood sugar levels. Insulin deficiency can lead to the development of diabetes.

It also stands out here, which is an insulin antagonist. The production of somatostatin leads to the suppression of glucagon, insulin and growth hormone synthesis.

Mixed glands also include testicles and ovaries. They belong to the gonads, which have exocrine and intrasecretory functions. The formation and release of sperm and eggs, as well as responsibility for the production of sex hormones, are assumed.

The ovaries are responsible for the implementation of the endocrine and generative processes. They are located in the pelvic area. Their length varies from two to five centimeters. The mass of the ovaries varies from five to eight grams. The width of the ovaries ranges from two to two and a half centimeters.

The ovaries are also responsible for the maturation of eggs and the production of:

• progesterone.

There is a softening of the cervix, which contributes to the successful resolution of the burden.

The testicles, located in the scrotum, are responsible for endocrine and generative functions. They are responsible for the formation and maturation of spermatozoa. They also take part in the formation of testosterone.

Heart, kidneys and CNS

The most important part of the endocrine system are the kidneys. An important role is played by the “engine” of a person, the heart, as well as the central nervous system. The kidneys carry out excretory and endocrine functions. Synthesis of renin is carried out by the juxtaglomerular apparatus. Renin is responsible for regulating vascular tone. In addition, the kidneys are responsible for the synthesis of erythroethin. It is responsible for the red blood cells in the bone marrow.

In the atrium, production is carried out. The heart also influences the production of sodium by the kidneys.

The most important hormones of the nervous and endocrine systems are enkephalins. Their synthesis is carried out in the central nervous system. Their main function is to get rid of pain syndrome. For this reason, they are also referred to as endogenous opiates. The action of neurohormones is similar to that of morphine.

Features of the glands of external secretion

An important role is played by exocrine glands. It is the glands of external secretion that secrete a variety of substances on the surface of the body, as well as into the internal environment of the human body. They are responsible for the formation of the species and individual aroma. Another important function is to protect the body from the penetration of harmful microbes. Their secret has a bactericidal and mycostatic effect.

four glands

External secretion glands include:

• dairy;
• sweat;
• salivary and lacrimal.

They are directly involved in the regulation of both interspecific and intraspecific relations.

What are they responsible for?

Salivary glands are small and large. They are located in the human mouth. Small glands are located in the submucosa. Major salivary glands are paired organs located outside the oral cavity.

The course of secretory processes is usually carried out during the period of activity of hormonal processes. The main trigger is hormonal restructuring. The greatest intensity of secretory processes is observed closer to adolescence.

The mammary glands are presented in the form of transformed sweat skin glands. Their laying is carried out at 6-7 weeks. At first, they are like seals in the epidermis. Then there is the formation of milk points. Before puberty, the mammary glands are inactive. Boys and girls develop differently.

The sweat glands involved in the process of thermoregulation are responsible for the production of sweat. They are represented by the simplest tubes, the ends of which are folded.

Conclusion

The radical absence of any of the glands can lead to disruption of the functioning of the others. Sometimes death occurs. Today, by means of potent medicines, only the replacement of thyroid hormones can be carried out.

Bibliography

1. Arterial hypertension in pregnant women Preeclampsia (preeclampsia). Makarov O.V., Volkova E.V. RASPM; Moscow; TsKMS GOU VPO RGMU.-31 p.- 2010.
2. New honey. technology (Methodological recommendations) "Management of preterm pregnancy complicated by premature rupture of membranes"; Makarov O.V., Kozlov P.V. (Edited by Volodin N.N.) - RASPM; Moscow; TsKMS GOU VPO RSMU-2006.
3. Anomalies of labor activity: a guide for physicians. UMO certification for medical education. Podtetenev A.D., Strizhova N.V. 2006 Publisher: MIA.
4. Emergency care in obstetrics and gynecology: a brief guide. Serov V.N. 2008 Publisher: Geotar-Media.
5. Ectopic pregnancy. UMO certification for medical education. Sidorova I.S., Guriev T.D. 2007 Publisher: Practical Medicine
6. Non-developing pregnancy. Radzinsky V.E., Dimitrova V.I., Mayskova I.Yu. 2009 Publisher: Geotar-Media.

Accent placement: INTERNAL SECRETION

INTERNAL SECRETION (lat. secretio - secretion) - the ability of a certain group of human and animal glands (endocrine glands, silt "endocrine glands) to secrete specific products of their vital activity ( hormones) directly into the blood or tissue fluid, and not into the external environment (as, for example, sweat glands) and not into the cavity of internal organs (for example, glands gastrointestinal tract). glands V. s. are: pituitary gland, thyroid gland, paired parathyroid (parathyroid) glands, adrenal glands, male (testes) and female (ovaries) gonads (their intrasecretory elements). The organ B.

With. is also an islet apparatus (department) of the pancreas. The endocrine glands also include the goiter, or thymus, gland (thymus) and the pineal gland (pineal gland), although the belonging of these formations to the endocrine glands cannot currently be considered strictly proven.

Specific biologically active substances secreted by the glands of V. s. - hormones, entering the blood, are carried throughout the body and change the metabolism and energy, the activity of the nervous system and internal organs, stimulating or inhibiting their work. Hormones affect growth, physical. and psychic. development, puberty, the development of secondary sexual characteristics, pigmentation, milk secretion, change the tone of smooth muscles, activate the growth and differentiation of tissues and organs.

In addition to specific effects on the activity of enzymes, vitamins and certain types metabolism (carbohydrate, protein, fat, mineral), each gland with its hormones in one way or another has an impact (direct or indirect) on other types of metabolism. The pituitary gland produces the so-called. throne hormones that stimulate the activity of other glands V. s. (gonadotropic - stimulating the sex glands, thyrotropic - activating the function of the thyroid gland, etc.). Thus, the functional state of all glands of V. s. and their effect on the body are closely interrelated. They represent a single physiological system, in regulation of activity a cut an essential role belongs to the central nervous system. For its part, V.'s glands with. have a certain effect on the activity of the nervous system, being an important link in a single system of neurohumoral regulation of functions in the body. All this testifies that V.'s glands of page. the hormones they secrete, participating in the regulation of life processes at all stages of development, including the embryonic period, the period of intensive growth of the body and its puberty, as well as in the process of vital activity of a mature organism, play a large role in its formation and regulation of activity. various bodies and functional systems.

Despite the fact that V.'s glands of page. are in close connection with each other and the defeat of one gland is usually accompanied by a violation of the function of other glands, diseases of individual glands of V. s. cause the symptoms, characteristic of defeat of each of them, allowing to define them as independent diseases, to-rye it is accepted to call endocrine. Violations of the activity of the endocrine glands are of two kinds: a) increased activity of the gland - hyperfunction, with a cut, an increased amount of the hormone is formed and released into the blood, and b) weakening of the activity of the gland - hypofunction when a reduced amount of the hormone is formed and released into the blood.

With damage to the pituitary gland, which is subdivided into the anterior (glandular), middle and posterior (nervous) lobes, develops whole line diseases. Hyperfunction of the anterior pituitary gland at an early age, when the body is still growing, in some cases leads (due to excessive production of the so-called growth hormone) to the development gigantism: the growth of such people can reach 2.5 - 2.6 m, the growth of the external genital organs increases (with a weakening of sexual desire). If such hyperfunction (with a tumor, chronic inflammation) occurs at the end of growth, it may develop acromegaly(increase in hands and groans, superciliary arches, cheekbones, jaws, etc.). With certain tumors of the anterior pituitary gland, fullness increases, bluish-purple cicatricial stripes (striae) appear on the body, blood pressure rises, menstruation disappears in women, and signs of diabetes mellitus sometimes appear ( Itsenko-Cushing's disease). With hypofunction of the anterior pituitary gland in early childhood (as a result of insufficient formation of growth hormone), nanism (dwarf growth) develops; the growth of bones and the development of the genital organs are suspended, the metabolism is reduced, secondary sexual characteristics do not develop.

With insufficient formation of “tropic” hormones in the anterior lobe of the pituitary gland, the activity of the corresponding other glands of the ventricular gland weakens. and the body's ability to adapt to harmful effects. With damage to the posterior lobe of the pituitary gland or related departments of the hypothalamic. increased thirst appears in the brain region (patients drink up to 10-15 liters of water per day) and, accordingly, urination increases sharply ( diabetes insipidus). With a complete lesion of the pituitary gland, severe exhaustion, sharp weight loss, weakness develop, teeth fall out, etc. ( pituitary cachexia).

Damage to the thyroid gland leads with its hyperfunction to thyrotoxicosis (Graves' disease). With hyperfunction and atrophy of this gland, which occurs in early childhood, cretinism develops, accompanied by growth retardation, mental retardation, sometimes reaching idiocy. Hypothyroidism in more late age leads to myxedema. Light and early forms of hyper- or hypothyroidism are usually called (respectively) hyper- or hypothyroidism. In areas where there is a lack of iodine in the water, which is part of the thyroid hormone - thyroxine, often develops endemic goiter.

With excessive production of the hormone of the parathyroid glands (for example, with a tumor), a disease of the bone skeleton occurs - parathyroid osteodystrophy, characterized by extraordinary softness and fragility of bones. With hypofunction of the parathyroid glands, tetany develops, edges in people (more often in children, pregnant women and nursing mothers) is expressed in the appearance of muscle spasms of the limbs, face, pharynx; hands during convulsive attacks are compressed - reduced. Insufficiency of the function of the parathyroid glands also leads (especially in young age) to tooth decay, early hair loss, weight loss.

Among the diseases of the adrenal glands, 2 forms are most common: bronze disease (most often caused by bilateral tuberculosis of the adrenal glands), with a cut, the main symptoms are skin pigmentation and severe muscle weakness (adynamia), and tumors. With tumors of the adrenal cortex (adenomas) in women, due to advanced education androgens (substances acting on the type of male sex hormone), changes in appearance are observed, masculine features appear (mustache, beard, body hair, development of muscles and skeleton according to the male type). Sometimes the nek-ry symptoms characteristic of Itsenko's illness — Cushing join to it. With tumors of the adrenal medulla, due to the increased release of its hormone - adrenaline, in patients with paroxysmal increases in blood pressure, an increase in blood sugar, temperature fluctuations are observed. With insufficiency of the function of the cortical layer of the adrenal glands, a number of pathological conditions develop. conditions associated mainly with reduced adaptability (adaptation) to the action of various harmful factors of the external and internal environment (cold, starvation, physical and mental trauma, etc.), as well as disorders of water-salt metabolism.

When the islet apparatus of the pancreas is damaged, diabetes, osn. to-rogo manifestations are increase in content of sugar in blood and its allocation with urine. This is due to insufficient production of insulin. If this is accompanied by a deficiency in the formation of another pancreatic hormone - lipocaine, then fatty liver develops. In severe forms of diabetes, there is a development ketosis- poisoning of the body with excessively formed products of fat metabolism. With tumors of the insular tissue, a sharp hypoglycemia(decrease in blood sugar).

The delay or premature and excessive development of primary and secondary sexual characteristics are connected by hl. arr. with hypo- or hyperfunction of the gonads and the influence of their hormones. Insufficiency in the development of the sex and some other endocrine glands in adolescence can be one of the causes of infantilism,

For the treatment of diseases of the glands V. s. currently widely used various hormonal drugs, radiant energy, operative surgical methods, dietic. nutrition, etc. Treatment is more successful, the earlier the disease is detected and the correct diagnosis is made. special attention children demand in this respect. Therefore, at the slightest suspicion of a violation of the function of any of the glands of V. s. (gradual and progressive weight loss or obesity, unexplained lethargy or excessive mental and physical excitability, delayed or untimely increase in growth, decreased mental abilities, etc.), it is necessary to refer the child to a specialist doctor.

Human hormones and their functions: a list of hormones in tables and their effect on the human body

Lit .: Sokolov D.D., Endocrine diseases in children and adolescents. M., 1952; Baranov VG, Diseases of the endocrine system and metabolism, L., 1955; Vasyukova E. A. (ed.), Guide to clinical endocrinology, M., 1958.

G. L. Shreiberg. Moscow.

Sources:

1. Pedagogical encyclopedia. Volume 1. Ch. editor - A.I. Kairov and F.N. Petrov. M., 'Soviet Encyclopedia', 1964. 832 column. with illustrations, 7 sheets. ill.

Endocrine glands and their importance.

All processes occurring in our body are regulated by the nervous and humoral systems. Plays a significant role in the regulation of the physiological functions of the body hormonal system operating through chemical substances through body fluids (blood, lymph, intercellular fluid).

Endocrine system - table of hormones and their functions

The main organs are systems - the pituitary gland, thyroid gland, adrenal glands, pancreas, gonads.

There are two types glands. Some of them have ducts through which substances are released into the body cavity, organs or onto the surface of the skin.

They are called glands of external secretion. External secretion glands are lacrimal, sweat, salivary, gastric glands, glands that do not have special ducts and secrete substances into the blood flowing through them are called endocrine glands. These include the pituitary gland, thyroid gland, thymus gland, adrenal glands and others.

Hormones- biologically active substances. Hormones are produced in small amounts, but remain active for a long time and are carried throughout the body with the bloodstream.

Endocrine glands:

Pituitary. Located at the base of the brain. A growth hormone. It has a great impact on the growth of a young organism.
adrenal glands. Paired glands adjacent to the apex of each kidney. Hormones - norepinephrine, adrenaline. Regulates water-salt, carbohydrate and protein metabolism. Stress hormone, control of muscle activity, cardiovascular system.
Thyroid. It is located on the neck in front of the trachea and on the side walls of the larynx. The hormone is thyroxine. regulation of metabolism.
Pancreas. Located under the stomach. The hormone is insulin. Plays an important role in carbohydrate metabolism.
gonads. Male testes are paired organs located in the scrotum. Female - ovaries - in the abdominal cavity. Hormones - testosterone, female hormones. Participates in the formation of secondary sexual characteristics, in the reproduction of organisms.
With a lack of growth hormone produced by the pituitary gland, dwarfism occurs, with hyperfunction - gigantism. With hypofunction of the thyroid gland in adults, mexedema occurs - metabolism is reduced, body temperature drops, the rhythm of heart contractions is weakened, and the excitability of the nervous system decreases. In childhood, cretinism (one of the forms of dwarfism) is observed, physical, mental and sexual development is delayed. Lack of insulin leads to diabetes. With an excess of insulin, the level of glucose in the blood drops sharply, this is accompanied by dizziness, weakness, hunger, loss of consciousness and convulsions.

FUNCTIONS OF THE GLANDS

The activity of the endocrine glands is under the control of numerous direct and feedback connections in the body. The main regulator of their functions is the hypothalamus, which is directly connected with the main endocrine gland - the pituitary gland, the influence of which extends to other peripheral glands.

FUNCTIONS OF THE HYPOPHYSIS

The pituitary gland is made up of three lobes:

1) anterior lobe or adenohypophysis,

2) intermediate share and

3) posterior lobe or neurohypophysis.

In the adeno-pophysis, the main secretory function is performed by 5 groups of cells that produce 5 specific hormones. Among them are tropic hormones (Latin tropos - direction), which regulate the functions of peripheral glands, and effector hormones that directly act on target cells. Tropic hormones include the following: corticotropin or adrenocorticotropic hormone (ACLT), which regulates the functions of the adrenal cortex; thyroid-stimulating hormone (TSH), which activates the thyroid gland; gonadotropic hormone (GTG), which affects the functions of the sex glands.

Effector hormones are somatotropin and hormone (GH) or somatotropin, which determines the growth of the body, and prolactin, which controls the activity of the mammary glands.

The release of hormones of the anterior pituitary gland is regulated by substances formed by neurosecretory cells of the hypothalamus - hypothalamic neuropeptides: stimulating secretion - liberins and inhibiting it - with t and t and n and m and. These regulatory substances are delivered by the blood stream from the hypothalamus to the anterior pituitary gland, where they influence the secretion of hormones by the pituitary cells.

Somatotropin is a species-specific protein that determines body growth (mainly increases the growth of bones in length).

Genetic engineering work with the introduction of rat somatotropin into the genetic apparatus of mice made it possible to obtain super mice twice as large. However, modern studies have shown that somatotropin of organisms of one species can increase body growth in species at lower stages of evolutionary development, but is not effective for more highly developed organisms. At present, a mediator substance has been found that transmits the effects of growth hormone on target cells - somatomedin, which is produced by cells of the liver and bone tissue. Somatotropin provides protein synthesis in cells, accumulation of RNA, enhances the transport of amino acids from the blood to cells, promotes the absorption of nitrogen, creating a positive nitrogen balance in the body, and helps to utilize fats. The secretion of somatotropic hormone increases during sleep, during physical exertion, injuries, and certain infections. In the pituitary gland of an adult, its content is about 4-15 mg, in women, its average amount is slightly higher. Especially increases the concentration of growth hormone in the blood of adolescents during puberty. During starvation, its concentration increases by 10-15 times.

Excessive release of somatotropin at an early age leads to a sharp increase in body length (up to 240-250 cm) - gigantism, and its deficiency - to growth retardation - dwarfism. Pituitary giants and dwarfs have a proportional physique, but they have changes in some body functions, in particular, a decrease in the intrasecretory functions of the gonads. An excess of somatotropin in the adult state (after the end of body growth) leads to the growth of parts of the skeleton that have not yet completely ossified - lengthening of the fingers and toes, hands and feet, ugly growth of the nose, chin, and also to an increase in internal organs. This condition is called acromegaly.

Prolactin regulates the growth of the mammary glands, the synthesis and secretion of milk (excretion of milk is provided by another hormone - oxytocin), stimulates the instinct of motherhood, and also affects the water-salt metabolism in the body, erythropoiesis, causes postpartum obesity, etc.

effects. Its release is reflexively activated by the act of sucking. Due to the fact that prolactin supports the existence of the corpus luteum and the production of the hormone progesterone by it, it is also called luteotropic hormone.

Corticotropin (adrenocorticotropic hormone - ACTH) is a large protein, during the formation of which melanotropin (affecting the formation of melanin pigment) and an important peptide - endorphin, which provide analgesic effects in the body, are released as by-products. The main effect of corticotropin is on the functions of the adrenal cortex,

especially on the formation of glucocorticoids. In addition, it causes the breakdown of fats in adipose tissue, increases the secretion of insulin and somatotropin. Stimulate the release of corticotropin various stress stimuli - strong pain, cold, significant physical exertion, psycho-emotional stress. Contributing to the strengthening of protein, fat and carbohydrate metabolism in stressful situations, it provides an increase in the body's resistance to the action of adverse environmental factors.

List of hormones

i.e., it is an adaptive hormone.

Thyrotropin (thyroid-stimulating hormone - TSH) increases the mass of the thyroid gland, the number of active cells, promotes the capture of iodine, which generally enhances the secretion of its hormones. As a result, the intensity of all types of metabolism increases, body temperature rises. The formation of TSH increases with a decrease in the external temperature of the environment and is inhibited by injuries, pain. The secretion of TSH can be caused by a conditioned reflex - by signals preceding cooling, i.e. controlled by the cortex hemispheres. This is of great importance for hardening processes, training to low temperatures.

Gonadotropic hormones (GTG) - follitropin and lutropin (they are also called follicle-stimulating and luteinizing hormones) - are synthesized and secreted by the same pituitary cells, they are the same in men and women and are synergistic in their action. These molecules are chemically protected from destruction in the liver. HTG stimulates the formation and secretion of sex hormones, as well as the function of the ovaries and testes. The content of HTG in the blood depends on the concentration of male and female sex hormones in the blood, on reflex influences during intercourse, on various factors external environment, on the level of neuropsychiatric disorders.

The posterior pituitary gland secretes the hormones vasopressin and oxytocin, which are formed in the cells of the hypothalamus, then through the nerve fibers enter the neurohypophysis, where they accumulate and are then released into the blood.

Vasopressin (lat.vas - vessel, pressus pressure) has a twofold physiological effect in organism.

First, it causes constriction of blood vessels and an increase in blood pressure.

Secondly, this hormone increases the reabsorption of water into renal tubules, which causes an increase in concentration and a decrease in the volume of urine, i.e. it acts as an antidiuretic hormone (ADH). Its secretion into the blood is stimulated by changes in water-salt metabolism, physical activity, and emotional stress. Depressed when alcohol is consumed

secretion of vasopressin (ADH), increased urine output and dehydration occurs. When sharp drop the production of this hormone causes diabetes insipidus, manifested in the pathological loss of water by the body.

Oxytocin stimulates uterine contractions during childbirth, the release of milk by the mammary glands. Its secretion is enhanced by impulses from the mechanoreceptors of the uterus when it is stretched, as well as by the influence of the female sex hormone estrogen.

The intermediate lobe of the pituitary gland is almost not developed in humans, there is only a small group of cells that secrete melanotropic hormone, educative melanin - skin and hair pigment. Basically, this function in humans is provided by corticotropin of the anterior pituitary gland.

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Functions of the endocrine system

Maintenance homeostasis in the body requires the coordination of many different systems and organs.

One of communication mechanisms between neighboring cells, as well as between cells and tissues in distant parts of the body is the interaction through the release of chemicals called hormones which are produced endocrine system.

Hormones are released into biological fluids usually in the blood.

1.5.2.9. Endocrine system

The blood carries them to the target cells, where the hormones cause the necessary reaction.

Cells that secrete hormones are often located in specific organs called endocrine glands.

Cells, tissues and organs that secrete hormones are endocrine system.

Some of the regulatory functions endocrine system include:

• control heart rate,
• control blood pressure,
• control immune response for an infection
• process control breeding, growth And development organism,
• level control emotional state.

Glands of the endocrine system

The endocrine system consists of:

Many other organs such as liver, leather, kidneys and parts digestive And circulatory systems, produce hormones in addition to their main specific physiological functions.

Endocrine glands (endocrine glands) are glands that release hormones directly into the bloodstream through the blood vessels passing through them, while exocrine glands secrete their secretions through ducts or tubes.

Examples of exocrine glands are sweat glands, salivary glands And lacrimal glands.

Types of hormones - steroid and non-steroid hormones and their mechanisms of action

The endocrine system produces two main types of hormones:

1. Steroid hormones
2. Not steroid hormones

Steroid hormones

Steroid hormones, such as cortisol, are produced from cholesterol.

Each type of steroid hormone consists of a central structure of four carbon rings with different side chains attached to them, which determine the specific and unique properties of the hormone.

Inside endocrine cells, steroid hormones are synthesized in smooth endoplasmic reticulum.

Because steroid hormones are hydrophobic, they bind to a carrier protein that carries them through the bloodstream.

Fat-soluble steroid hormones can pass through the target cell membrane.

Inside the target cell in the cytoplasm, steroid hormones attach to a receptor protein molecule.

This hormone-receptor complex then enters the nucleus, where it binds to and activates a specific gene on the molecule. DNA.

The activated gene then produces an enzyme that initiates the desired chemical reaction within the cell.

Non-steroidal hormones

Non-steroidal hormones, such as adrenaline, are composed of either proteins, peptides, or amino acids.

These hormone molecules are not fat soluble, so they usually cannot get inside the cell through the plasma membrane in order to exert their effect.

Instead they bind to receptors on the surface of target cells. This binding to the receptors then triggers a specific chain of chemical reactions within the cell.

endocrine gland	Hormones	Hormonal effect
Pituitary
Pituitary gland, (anterior lobe (adenohypophysis))	a growth hormone	promotes the growth of body tissues
Pituitary (anterior)	prolactin	promotes milk production
	thyroid-stimulating hormone	stimulates the release of thyroid hormones
	adrenocorticotropic hormone	stimulates the release of hormones by the adrenal cortex
	follicle-stimulating hormone	stimulates the production of gametes
	luteinizing hormone	stimulates the production of androgens by the gonads in men; stimulates ovulation and production of estrogen and progesterone in women
Pituitary gland, (posterior lobe (neurohypophysis))	antidiuretic hormone	stimulates water reabsorption by the kidneys
Pituitary (posterior)	oxytocin	stimulates uterine contractions during childbirth
Thyroid gland
Thyroid	thyroxine, triiodothyronine	stimulates metabolism
Thyroid	calcitonin	reduces the level of Ca 2+ in the blood
Parathyroid gland	parathyroid hormone (parathormone)	increases the level of Ca 2+ in the blood
adrenal glands
Adrenal(cortex)	aldosterone	increases the level of Na + in the blood
Adrenal (cortex)	cortisol, corticosterone, cortisone
Adrenal(medulla) Adrenal (medulla)	epinephrine, norepinephrine	stimulates the fight-or-flight response
Pancreas
Pancreas	insulin	lowers blood glucose levels
Pancreas	glucagon	raises blood glucose levels
pineal gland
pineal gland	melatonin	governs circadian rhythms organism
thymus
Thymus gland (thymus)	thymosin	stimulates the production and maturation of lymphocytes

1961. Hormone receptors are found in the cells of target organs.

1962. At rest, the main form of blood transport of hormones to targets is their transfer in combination with specific plasma proteins.

1963. Adrenocorticotropic hormone regulates the formation and excretion of glucocorticoids.

1964. Growth hormone has practically no special target organ.

1965. Progesterone is synthesized in the ovary.

1966 Oxytocin is secreted by the hypothalamus and stored in the neurohypophysis.

1967. Thyroxine is synthesized in the thyroid gland.

1968. Insulin, glucocorticoids predominantly affect carbohydrate metabolism.

1969. Glucocorticoids are predominantly involved in the body's adaptation to potent factors.

1970. Adrenaline predominantly affects the energy of muscle contractions.

1971. Somatotropic hormone is synthesized in the anterior pituitary gland.

1972. Antidiuretic hormone is synthesized in the hypothalamus, accumulates in the posterior pituitary gland, from where it enters the blood.

1973. Adrenocorticotropic hormone is synthesized in the anterior pituitary gland.

1974. Water retention in the body is associated with the action of the hormone ADH (antidiuretic).

1975. Glands of internal secretion are called such glands that do not have excretory ducts and secrete their secrets into the blood.

1976. The ovaries and placenta are endocrine glands.

1977. Brunner's and Lieberkün's glands do not belong to endocrine glands.

1978. The product of secretion of the endocrine glands are hormones.

1979. Hormones have the property of specificity - the effect only on their target.

1980. High biological activity is inherent in hormones.

1981. Hormones have a small molecular size, which allows them to act intracellularly.

1982. Hormones are rapidly destroyed by tissues.

1983. The use of animal hormones for human treatment is possible, since hormones are not species-specific.

1984. Somatotropic hormone is produced in the adenohypophysis.

1985. Growth hormone affects the entire body.

Growth hormone stimulates protein synthesis.

1987. Under the influence of growth hormone, nitrogen balance becomes positive.

1988. Growth hormone promotes the mobilization of fats from the depot.

1989. Growth hormone promotes the breakdown of glycogen.

1990. Growth hormone contributes to the retention of calcium, sodium and phosphorus in the body.

1991. Growth hormone accelerates body growth.

1992. Pituitary dwarfism is a slowdown in body growth with a lack of somatotropic hormone.

1993. Gigantism is an increase in height and body weight under the influence of an excess of somatotropic hormone.

1994. With an excess of somatotropic hormone, acromegaly occurs in an adult.

1995. Acromegaly is an increase in the feet, hands, nose, ears, internal organs in an adult with an excess of somatotropic hormone.

1996. Thyroid-stimulating hormone is produced in the adenohypophysis.

1997. Thyroid-stimulating hormone affects the thyroid gland.

Hormones and their effect on the body table

With a lack of thyroid-stimulating hormone, thyroid insufficiency occurs.

1999. Adrenocorticotropic hormone is produced in the adenohypophysis.

2000. Adrenocorticotropic hormone (ACTH) acts on the adrenal glands.

2001. With a lack of ACTH, adrenal insufficiency occurs.

2002. With an excess of ACTH, hyperfunction of the adrenal glands occurs.

2003. Gonadotropic hormones include follicle-stimulating and luteinizing.

2004. Intermedin is produced in the middle lobe of the pituitary gland.

2005. Intermedin affects skin color.

2006. The production of intermedin a is promoted by sunlight.

2007. With a lack of intermedin, a violation of skin pigmentation occurs.

2008. Hormones are not produced in the neurohypophysis.

2009. Oxytocin is produced in the hypothalamus.

2010. Oxytocin affects the uterus and mammary glands.

2011. Oxytocin induces uterine contractions.

2012. Oxytocin induces milk ejection.

2013. Antidiuretic hormone (ADH) is produced in the hypothalamus.

2014. ADH promotes water reabsorption in the collecting ducts.

2015. Deficiency of ADH results in diabetes insipidus.

2016. ADH raises blood pressure.

2017. The hypothalamus regulates the production of adenohypophysis hormones.

2018. Releasing factors are produced in the hypothalamus.

2019. Releasing factors promote the synthesis of adenohypophysis hormones.

2020. There are no releasing factors for prolactin in the hypothalamus.

2021. Inhibiting factors (statins) are produced in the hypothalamus.

2022. Corticostatin inhibits ACTH synthesis.

2023. Thyrostatin inhibits the synthesis of thyroid-stimulating hormone.

2024. Somatostatin inhibits the synthesis of growth hormone.

2025. Prolactostatin inhibits prolactin synthesis.

2026. Melatonin is produced in the pineal gland.

2027. Melatonin promotes skin lightening.

2028. sunlight interferes with the synthesis of melatonin.

2029. Melatonin slows down puberty.

2030. Thyrotropic hormone is not produced in the thyroid gland.

2031. Iodine is necessary for the synthesis of thyroid hormones.

2032. Thyroxin affects all body tissues.

2033. Thyroxin promotes protein breakdown.

2034. Thyroxin promotes the breakdown of fats.

2035. Thyroxin promotes the breakdown of glycogen.

2036. Thyroxin increases basal metabolism.

2037. With a lack of thyroxin, a child develops cretinism.

2038. With a lack of thyroxine in adults, myxedema occurs.

2039. With an excess of thyroxin, Graves' disease occurs.

2040. Thyrocalcitonin is produced in the thyroid gland.

2041. Thyrocalcitonin affects the bones.

2042. Thyrocalcitonin affects the exchange of calcium and phosphorus.

2043. Thyrocalcitonin promotes the deposition of calcium in the bones.

2044. Antagonist of thyrocalcitonin is parathormone.

2045. Parathyroid hormone is produced in the parathyroid glands.

2046. Parathormone affects the kidneys, gastrointestinal tract and bones.

2047. Parathormone leaches calcium from bones.

2048. Parathyroid hormone increases calcium reabsorption in the tubules.

2049. Parathyroid hormone increases the absorption of calcium in the intestine.

2050. Under the influence of parathyroid hormone, the calcium content in the blood increases.

2051. With an excess of parathyroid hormone, osteoporosis occurs.

2052. With a lack of parathyroid hormone, convulsions occur.

2053. Alpha cells of the islets of Langerhans produce glucagon.

2054. Beta cells of the islets of Langerhans produce insulin.

2055. Insulin increases the permeability of the cell membrane for glucose.

2056. Under the influence of insulin, the content of glucose in the blood decreases.

2057. Insulin promotes the synthesis of fat from glucose.

2058. Insulin promotes the synthesis of proteins isamino acids.

2059. With insulin deficiency, diabetes mellitus occurs.

2060. The amount of urine in a diabetic patient increases.

2061. With an increase in the amount of insulin, an excess of glucose appears in the urine and carries water along with it according to the laws of osmosis.

2062. Glucagon on carbohydrate metabolism promotes the breakdown of glycogen in the liver.

2063. Under the influence of glucagon, the content of glucose in the blood increases.

2064. Adrenaline and norepinephrine are synthesized in the adrenal medulla.

2065. Adrenaline speeds up and intensifies heart contractions.

2066. Adrenaline constricts the vessels of the internal organs and dilates the coronary and cerebral vessels.

2067. Adrenaline relaxes the muscles of the bronchi.

2068. Adrenaline lowers the secretion of all digestive juices.

2069. Adrenaline depresses smooth muscle GIT.

2070. Adrenaline increases basal metabolism.

2071. Adrenaline increases heat production and reduces heat transfer.

2072. Insufficiency of the adrenal glands does not lead to any disease.

2073. Mineralocorticoids are produced in the glomerular zone of the adrenal cortex.

2074. Glucocorticoids are produced in the fascicular zone of the adrenal cortex.

2075. Androgens and estrogens are produced in the reticular zone of the adrenal cortex.

2076. Mineralocorticoids promote sodium retention in the body.

2077. Mineralocorticoids increase the excretion of potassium in the urine.

2078. Mineralocorticoids increase blood pressure.

2079. With an excess of mineralocorticoids, hypertension and edema occur.

2080. Glucocorticoids regulate the metabolism of proteins, fats and carbohydrates.

2081. Stress leads to an increase in the synthesis of glucocorticoids.

2082. With a deficiency of glucocorticoids, there is a decrease in resistance to harmful effects.

2083. Heavy physical activity increases the content of glucocorticoids in the blood.

2084. Pain increases the content of glucocorticoids in the blood.

2085. Androgens are synthesized in the gonads and adrenal cortex.

2086. Estrogens are synthesized in the sex glands and the adrenal cortex.

2087. Women increased content androgens leads to the appearance of secondary male sexual characteristics.

2088. In men, an increased content of estrogen leads to the disappearance of secondary male sexual characteristics.

2089. Tissue hormones are hormones that are produced by specialized cells of the body that are not related to the endocrine glands.

2090. Tissue hormones are not synthesized in the skin.

2091. Thymosin is synthesized in the thymus gland.

2092. Thymosin increases the number of lymphocytes in the blood.

2093. Hormones, in comparison with the nervous regulation of functions, realize their effect more slowly and uneconomically.

2094. The nervous system controls the endocrine glands through the autonomic nervous system, through neurosecretions and through changes in tissue sensitivity.

2095. Neurosecretion is the secretion of a neurohormone by specialized nerve cells into the blood (lymph).

2096. Under the metabolic effect of hormones understand the effect on the effector that changes the metabolism.

2097. Under the morphogenetic effect of hormones understand the impact on the processes of growth and differentiation of cells.

2098. The feedback principle is inherent in the mechanism of hormonal regulation of physiological functions.

2099. Hormonal regulation of physiological functions is carried out according to the principle of negative feedback.

2100. During exercise, the level of insulin in the blood rises. Under these conditions, the activity of the middle lobe of the pituitary gland increases.

2101. After the removal of the pituitary gland in puppies, there is a cessation of physical growth, sexual and mental development, underdevelopment of the endocrine glands, because the pituitary gland produces somatotropic hormone that stimulates protein synthesis and growth.

2102. The posterior lobe of the pituitary gland is richly supplied with nerve fibers coming from the supra-optic and paraventricular nucleus of the hypothalamus.

2103. Under stress, the level of catecholamines in the blood increases, because this increases the tone of the sympathetic division of the autonomic nervous system.

2104. After organ transplantation, a course of hormone therapy with corticoids is mandatory, because corticoids suppress immune reactions rejection of the transplanted organ.

2105. Insulin is a vital hormone because it is the only hormone that increases the permeability of cell membranes to glucose.

2106. The hypothalamus is called the conductor of the endocrine orchestra, because all endocrine glands are target organs of pituitary hormones.

Republic Act 2107 endocrine function pancreas increases blood glucose levels.

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