Useful properties of hormones. General properties of hormones

Hormones, their functions and properties

Characteristics of the endocrine system

General physiology of endocrine glands

LECTURE №7

The value of the activity of sensory systems in sports

The effectiveness of performing sports exercises depends on the perception and processing of sensory information. These processes determine both the most rational organization of motor acts and the perfection of the athlete's tactical thinking.

Endocrine glands enter the system humoral regulation of body functions, together with a system of local self-regulation. Local self-regulation manifests itself in the action on neighboring cells of tissue hormones (histamine, serotonin, kinins and prostaglandins) and metabolic products (lactate).

Features of the endocrine glands:

Ø secrete substances that have a significant (even in very small concentrations) and specialized effects on metabolism, structure and function of organs and tissues.

Ø differ from the glands of external secretion in that they secrete the substances they produce directly into the blood, in connection with this they are called endocrine (endo - inside, krin-en - secrete), and there are no external ducts.

Ø are small in size and mass, well supplied with blood vessels and braided with nerve fibers, since the activity of the endocrine glands is controlled by the nervous system.

Ø all glands are functionally closely related to each other and the defeat of one of them leads to a violation of the functions of all the others.

Hormones - biologically active substances produced by the endocrine glands and secreted into the bloodstream in response to specific signals. Hormones have a relative species specificity, which made it possible at the early stages of their use to compensate for the lack of hormones in humans by administering preparations derived from animal tissues. Today, many hormonal preparations are obtained synthetically, they are preferable to use, as they cause allergic reactions less often. Functions of hormones:

1. Impact on processes differentiation ( in the developing embryo)

2. Process regulation breeding – fertilization, egg implantation, pregnancy and lactation, differentiation and development of spermatozoa and eggs;

3. Influence at growth and development: The optimal growth of children is due to the combined action of growth hormone, thyroid hormones, insulin, and the presence of inadequate amounts of insulin antagonists or sex steroids can inhibit growth.

4. Security adaptation ( short-term and long-term) to changing environmental conditions, the quantity and quality of food consumed, external physical, chemical, biological and psychological influences;

5. Participation in the regulation of the rate of aging (for example, aging accompanied by a decrease in the secretion of sex hormones).

General properties of hormones:

1. Electoral action on sensitive cells: hormones increase or decrease the activity of cells that respond to them, which are called target cells. On the target cells are receptors - special protein molecules that recognize this hormone and interact with it. As a result of this interaction with the receptor, the hormone triggers a sequence of reactions in the target cell, which lead to a specific cellular response. Such a response includes the acceleration of some biochemical processes with the simultaneous inhibition of others. The influence of peptide hormones and amino acid derivatives (adrenaline, noradrenaline) is carried out by binding to receptors on the surface of cell membranes, and steroid hormones and thyroid hormones penetrate the cell, bind to the receptor in the cytoplasm, and then, in combination with the receptor, penetrate into the nucleus.

2. secretion rate of some hormones is associated with the wakefulness-sleep cycle, the secretion of other hormones depends on the age and gender, etc.

3. Information transmission systems. As soon as the hormone begins to act on a cell or group of cells that is sensitive to it, a signal simultaneously appears that inhibits the action of this hormone. This principle is called ʼʼfeedbackʼʼ. Preservation of the extremely important level of the hormone in the blood is supported by the mechanism negative feedback (ᴛ.ᴇ. with an excess of a hormone or substances formed under its action, the secretion of this hormone decreases, and with a deficiency it increases).

4. Time of action.

Ø Peptide hormones (hormones of the pituitary gland, pancreas, hypothalamic neuropeptides) have a duration of action from several seconds to minutes.

Ø Hormones in the form of proteins and glycoproteins (growth hormone) - from several minutes to hours.

Ø Steroids (sex and corticosteroids) - a few hours

Ø Iodthyronines (thyroid hormones) - several days

Hormones, their functions and properties - concept and types. Classification and features of the category "Hormones, their functions and properties" 2017, 2018.

It is one of the most important in the human body. It influences and regulates the work of all other organs in a certain way. This is possible due to the production of hormones - substances with extremely high biological activity.

They are produced, each of which is responsible for the synthesis of peculiar substances. Can you name the properties of hormones (basic)? Human physiology is quite complex, so many find it difficult to give a correct answer to this question.

General description of these biological structures

Hormones are complex biological structures. Their physiological feature lies in the fact that they are secreted exclusively by the endocrine glands of internal secretion into the blood. A feature of these organs is called small size, but excellent blood supply by an extensive network of blood vessels. The functioning of the endocrine glands is regulated by the nervous system. All of them are closely related. In the presence of any pathologies in one organ, certain changes are observed in the work of others.

Hormones are vital substances for humans. They are secreted by the endocrine glands in response to certain signals or under the influence of certain stimuli. Human physiology does not imply that the hormones produced by the body are of exclusive species.

In the presence of many endocrine diseases, the deficiency of certain substances can be filled with special preparations. Very often they are made not only from synthetic ingredients, but also from components that are obtained from animal tissues.

Why do people need these substances?

The functions of these biologically active substances are diverse:

• take a direct part in the processes of cell differentiation during the development of the embryo. This means that hormones cause less specialized structures to acquire more specific properties. These processes also occur in the adult organism during spermatogenesis, hematopoiesis, etc.;
• regulation of the reproduction process. These substances ensure the fertilization of the egg, its implantation, affect the successful course of pregnancy, start childbirth and lactation;
• influence on the physical growth of the organism and on its intellectual development. This is ensured by the joint action of many endocrine glands;
• ensuring short-term and long-term adaptation of the body to certain conditions (the quantity and quality of food consumed, the psycho-emotional state of a person, negative biological, chemical or physical effects, etc.);
• participation in the regulation of the rate of aging, which is determined by a decrease in the production of sex hormones.

Properties of these substances

List the general properties of hormones that are called in the medical literature. If you cannot give the correct answer, please read this information. The main properties of hormones are as follows:

• electoral action. This is ensured by the fact that only some cells in the human body are sensitive to them. They increase or decrease their activity in response to certain signals;
• the influence on their rate of secretion of such factors as sleep or wakefulness, age, gender of a person, and many others;
• the presence of a specific information transfer system. The mechanism of action of hormones is that when exposed to certain structures, signals arise that inhibit the secretion of these substances. This process is called feedback. Thanks to it, the necessary level of all substances produced by the endocrine glands is always maintained in the human blood;
• hormonal structures have a different period of action. Substances of a peptide nature (produced by the hypothalamic-pituitary system, pancreas) affect the human body from several seconds to minutes, protein and glycoprotein (somatotropin) - from several minutes to hours, steroids (sex, corticosteroids) - several hours, iodothyronines (produced by the thyroid gland) - a few days;
• action specificity. These biologically active substances cause certain reactions in the human body, to which no other structures can lead;
• remote action. Hormones are produced in one place, but can affect completely different areas in the human body;
• high activity. Hormones are secreted in small amounts, but this is enough to achieve the desired effect.

Mode of action of biologically active substances

The characteristic of the action of these biological structures is that they affect the human body in two ways. The first - through the nervous system, the second - humorally or directly to the desired tissues. Their action is ensured by the presence of specialized protein receptors on target cells, with which they can bind. The following types of interaction of these structures are distinguished:

• The first type includes thyroid hormones. They easily penetrate cell membranes. This does not require the presence of a special intermediary (mediator).
• The second type is characterized by the fact that they do not penetrate well into the cell and act on its surface. They require the presence of mediators.

Based on this division, two types of hormonal reception are distinguished. The first variety is called intracellular, which is characterized by the presence of a special receptor apparatus inside the cells. The second type is distinguished by its placement on the surface of the membrane. Such hormonal reception is called contact.

Features of cell receptors

Cellular receptors are special sections of cell membranes that, under the influence of hormones, form special complexes with them. They differ in the following properties:

• react only to certain substances and are completely insensitive to others;
• limited capacity for a particular hormone;
• located in specific areas of tissue.

Thanks to these properties, the action of all hormonal structures on the human body and its normal functioning is ensured.

The mechanism of interaction with the target cell

The mechanism of interaction of these biological structures is as follows:

1. A special complex is formed on the surface of the cell membrane, which includes special receptors.
2. Membrane adenylate cyclase is activated.
3. Formation of specific structures on the membrane surface in response to the action of biologically active substances.
4. The resulting complexes affect the cell in a specific way (stimulation of protein synthesis, glycogen breakdown, etc.).
5. Inactivation of emerging structures.

The nervous regulation of the action of hormones is that they interact with interoreceptors. As a result, the state of some centers changes, which leads to the closure of certain reflex arcs.

Biologically active substance (BAS), physiologically active substance (PAS) - a substance that in small quantities (mcg, ng) has a pronounced physiological effect on various functions of the body.

Hormone- a physiologically active substance produced or specialized endocrine cells, released into the internal environment of the body (blood, lymph) and has a distant effect on target cells.

Hormone - it is a signaling molecule secreted by endocrine cells that, through interaction with specific receptors on target cells, regulates their functions. Since hormones are information carriers, they, like other signaling molecules, have high biological activity and cause responses in target cells at very low concentrations (10 -6 - 10 -12 M/l).

Target cells (target tissues, target organs) - cells, tissues or organs that have specific receptors for a given hormone. Some hormones have a single target tissue, while others have effects throughout the body.

Table. Classification of physiologically active substances

Properties of hormones

Hormones have a number of common properties. They are usually formed by specialized endocrine cells. Hormones have a selective action, which is achieved by binding to specific receptors located on the surface of cells (membrane receptors) or inside them (intracellular receptors), and triggering a cascade of processes of intracellular hormonal signal transmission.

The sequence of events of hormonal signal transmission can be represented as a simplified scheme “hormone (signal, ligand) -> receptor -> second (secondary) messenger -> effector structures of the cell -> physiological response of the cell”. Most hormones lack species specificity (with the exception of ), which makes it possible to study their effects in animals, as well as to use hormones obtained from animals to treat sick people.

There are three variants of intercellular interaction with the help of hormones:

• endocrine(distant), when they are delivered to target cells from the place of production by blood;
• paracrine- hormones diffuse to the target cell from a nearby endocrine cell;
• autocrine - hormones act on the producer cell, which is also a target cell for it.

According to their chemical structure, hormones are divided into three groups:

• peptides (the number of amino acids up to 100, such as thyrotropin-releasing hormone, ACTH) and proteins (insulin, growth hormone, etc.);
• derivatives of amino acids: tyrosine (thyroxine, adrenaline), tryptophan - melatonin;
• steroids, cholesterol derivatives (female and male sex hormones, aldosterone, cortisol, calcitriol) and retinoic acid.

According to their function, hormones are divided into three groups:

• effector hormones acting directly on target cells;
• pituitary tron ​​hormones that control the function of peripheral endocrine glands;
• hypothalamic hormones that regulate the secretion of hormones by the pituitary gland.

Table. Types of action of hormones

Hormones circulate in the blood in a free (active form) and bound (inactive form) state with plasma proteins or formed elements. Free hormones are biologically active. Their content in the blood depends on the rate of secretion, the degree of binding, capture and metabolic rate in tissues (binding to specific receptors, destruction or inactivation in target cells or hepatocytes), removal with urine or bile.

Table. Physiologically active substances discovered recently

A number of hormones can undergo chemical transformations in target cells into more active forms. So, the hormone "thyroxine", undergoing deiodination, turns into a more active form - triiodothyronine. The male sex hormone testosterone in target cells can not only turn into a more active form - dehydrotestosterone, but also into the female sex hormones of the estrogen group.

The action of the hormone on the target cell is due to the binding, stimulation of a receptor specific to it, after which the hormonal signal is transmitted to the intracellular cascade of transformations. Signal transmission is accompanied by its multiple amplification, and the action of a small number of hormone molecules on a cell can be accompanied by a powerful response of target cells. Activation of the receptor by the hormone is also accompanied by the activation of intracellular mechanisms that stop the cell's response to the action of the hormone. These may be mechanisms that reduce the sensitivity (desensitization / adaptation) of the receptor to the hormone; mechanisms that dephosphorylate intracellular enzyme systems, etc.

Receptors for hormones, as well as for other signaling molecules, are localized on the cell membrane or inside the cell. The receptors of the cell membrane (1-TMS, 7-TMS and ligand-dependent ion channels) interact with hydrophilic (lyiophobic) hormones, for which the cell membrane is impermeable. They are catecholamines, melatonin, serotonin, protein-peptide hormones.

Hydrophobic (lipophilic) hormones diffuse through the plasma membrane and bind to intracellular receptors. These receptors are divided into cytosolic (receptors for steroid hormones - gluco- and mineralocorticoids, androgens and progestins) and nuclear (receptors for thyroid iodine-containing hormones, calcitriol, estrogens, retinoic acid). Cytosolic and estrogen receptors are bound to heat shock proteins (HSPs) to prevent their entry into the nucleus. The interaction of the hormone with the receptor leads to the separation of HSP, the formation of the hormone-receptor complex, and the activation of the receptor. The hormone-receptor complex moves to the nucleus, where it interacts with strictly defined hormone-sensitive (recognizing) DNA regions. This is accompanied by a change in the activity (expression) of certain genes that control the synthesis of proteins in the cell and other processes.

According to the use of certain intracellular pathways for the transmission of a hormonal signal, the most common hormones can be divided into a number of groups (Table 8.1).

Table 8.1. Intracellular mechanisms and pathways of action of hormones

Hormones control various reactions of target cells and through them - the physiological processes of the body. The physiological effects of hormones depend on their content in the blood, the number and sensitivity of receptors, and the state of post-receptor structures in target cells. Under the action of hormones, activation or inhibition of the energy and plastic metabolism of cells, the synthesis of various substances, including protein substances (metabolic action of hormones) can occur; change in the rate of cell division, its differentiation (morphogenetic action), initiation of programmed cell death (apoptosis); triggering and regulation of contraction and relaxation of smooth myocytes, secretion, absorption (kinetic action); changing the state of ion channels, accelerating or inhibiting the generation of electrical potentials in pacemakers (corrective action), facilitating or inhibiting the influence of other hormones (reactogenic action), etc.

Table. The distribution of the hormone in the blood

The rate of occurrence in the body and the duration of responses to the action of hormones depend on the type of stimulated receptors and the rate of metabolism of the hormones themselves. Changes in physiological processes can be observed after several tens of seconds and last for a short time upon stimulation of plasma membrane receptors (for example, vasoconstriction and an increase in blood pressure under the action of adrenaline) or occur after several tens of minutes and last for hours upon stimulation of nuclear receptors (for example, increased metabolism in cells and an increase in oxygen consumption by the body when thyroid receptors are stimulated by triiodothyronine).

Table. Time of action of physiologically active substances

Since the same cell can contain receptors for different hormones, it can simultaneously be a target cell for several hormones and other signaling molecules. The action of one hormone on a cell is often combined with the influence of other hormones, mediators, and cytokines. In this case, a number of signal transduction pathways can be triggered in target cells, as a result of the interaction of which an increase or inhibition of the cell response can be observed. For example, norepinephrine and can simultaneously act on a smooth myocyte of the vascular wall, summing up their vasoconstrictive effect. The vasoconstrictive effect of vasopressin can be eliminated or weakened by the simultaneous action of bradykinin or nitric oxide on smooth myocytes of the vascular wall.

Regulation of the formation and secretion of hormones

Regulation of the formation and secretion of hormones is one of the most important functions and nervous systems of the body. Among the mechanisms of regulation of the formation and secretion of hormones, there are the influence of the central nervous system, "triple" hormones, the influence of the concentration of hormones in the blood through the channels of negative feedback, the influence of the end effects of hormones on their secretion, the influence of daily and other rhythms.

Nervous regulation carried out in various endocrine glands and cells. This is the regulation of the formation and secretion of hormones by neurosecretory cells of the anterior hypothalamus in response to the flow of nerve impulses to it from various areas of the central nervous system. These cells have a unique ability to be excited and transform excitation into the formation and secretion of hormones that stimulate (releasing hormones, liberins) or inhibit (statins) the secretion of hormones by the pituitary gland. For example, with an increase in the flow of nerve impulses to the hypothalamus under conditions of psychoemotional arousal, hunger, pain, exposure to heat or cold, during infection and other emergency conditions, the neurosecretory cells of the hypothalamus release corticotropin-releasing hormone into the portal vessels of the pituitary gland, which enhances the secretion of adrenocorticotropic hormone. (ACTH) by the pituitary gland.

ANS has a direct effect on the formation and secretion of hormones. With an increase in the tone of the SNS, the secretion of triple hormones by the pituitary gland increases, the secretion of catecholamines by the adrenal medulla, thyroid hormones by the thyroid gland, and insulin secretion decreases. With an increase in the tone of the PSNS, the secretion of insulin and gastrin increases and the secretion of thyroid hormones is inhibited.

Regulation by tron ​​hormones of the pituitary gland used to control the formation and secretion of hormones by peripheral endocrine glands (thyroid, adrenal cortex, gonads). The secretion of tropic hormones is under the control of the hypothalamus. Tropic hormones get their name from their ability to bind (have affinity) to receptors on target cells that form individual peripheral endocrine glands. The tropic hormone to thyrocytes of the thyroid gland is called thyrotropin or thyroid stimulating hormone (TSH), to the endocrine cells of the adrenal cortex is called adrenocorticotropic hormone (ACTH). Tropic hormones to the endocrine cells of the gonads are called: lutropin or luteinizing hormone (LH) - to the Leydig cells, the corpus luteum; follitropin or follicle-stimulating hormone (FSH) - to follicle cells and Sertoli cells.

Tropic hormones, when their level in the blood increases, repeatedly stimulate the secretion of hormones by the peripheral endocrine glands. They may also have other effects on them. So, for example, TSH increases blood flow in the thyroid gland, activates metabolic processes in thyrocytes, their capture of iodine from the blood, and accelerates the processes of synthesis and secretion of thyroid hormones. With an excess amount of TSH, hypertrophy of the thyroid gland is observed.

Feedback regulation used to control the secretion of hormones from the hypothalamus and pituitary gland. Its essence lies in the fact that the neurosecretory cells of the hypothalamus have receptors and are target cells for the hormones of the peripheral endocrine gland and the triple hormone of the pituitary gland, which controls the secretion of hormones by this peripheral gland. Thus, if TSH secretion increases under the influence of hypothalamic thyrotropin-releasing hormone (TRH), the latter will bind not only to thyrocyte receptors, but also to receptors of neurosecretory cells of the hypothalamus. In the thyroid gland, TSH stimulates the production of thyroid hormones, while in the hypothalamus it inhibits further secretion of TRH. The relationship between the level of TSH in the blood and the processes of formation and secretion of TRH in the hypothalamus is called short loop feedback.

The secretion of TRH in the hypothalamus is also influenced by the level of thyroid hormones. If their concentration in the blood increases, they bind to the thyroid hormone receptors of neurosecretory cells of the hypothalamus and inhibit the synthesis and secretion of TRH. The relationship between the level of thyroid hormones in the blood and the processes of formation and secretion of TRH in the hypothalamus is called long loop feedback. There is experimental evidence that the hormones of the hypothalamus not only regulate the synthesis and release of pituitary hormones, but also inhibit their own release, which is defined by the concept ultra short loop feedback.

The totality of the glandular cells of the pituitary, hypothalamus and peripheral endocrine glands and the mechanisms of their mutual influence on each other were called systems or axes of the pituitary - hypothalamus - endocrine gland. The systems (axes) of the pituitary gland - hypothalamus - thyroid gland are distinguished; pituitary - hypothalamus - adrenal cortex; pituitary - hypothalamus - sex glands.

Influence of end effects hormones on their secretion takes place in the islet apparatus of the pancreas, C-cells of the thyroid gland, parathyroid glands, hypothalamus, etc. This is demonstrated by the following examples. An increase in blood glucose stimulates the secretion of insulin, and a decrease stimulates the secretion of glucagon. These hormones inhibit each other's secretion by a paracrine mechanism. With an increase in the level of Ca 2+ ions in the blood, the secretion of calcitonin is stimulated, and with a decrease - parathyrin. The direct influence of the concentration of substances on the secretion of hormones that control their level is a fast and effective way to maintain the concentration of these substances in the blood.

Among the considered mechanisms of regulation of hormone secretion, their final effects include the regulation of secretion of antidiuretic hormone (ADH) by the cells of the posterior hypothalamus. The secretion of this hormone is stimulated by an increase in the osmotic pressure of the blood, such as fluid loss. Reduced diuresis and fluid retention in the body under the action of ADH lead to a decrease in osmotic pressure and inhibition of ADH secretion. A similar mechanism is used to regulate the secretion of natriuretic peptide by atrial cells.

Influence of circadian and other rhythms on the secretion of hormones takes place in the hypothalamus, adrenal glands, sex, pineal glands. An example of the influence of the circadian rhythm is the daily dependence of the secretion of ACTH and corticosteroid hormones. Their lowest level in the blood is observed at midnight, and the highest - in the morning after waking up. The highest level of melatonin is recorded at night. The influence of the lunar cycle on the secretion of sex hormones in women is well known.

Definition of hormones

secretion of hormones the entry of hormones into the internal environment of the body. Polypeptide hormones accumulate in granules and are secreted by exocytosis. Steroid hormones do not accumulate in the cell and are secreted immediately after synthesis by diffusion through the cell membrane. The secretion of hormones in most cases has a cyclic, pulsating character. The frequency of secretion is from 5-10 minutes to 24 hours or more (a common rhythm is about 1 hour).

Bound form of the hormone- the formation of reversible complexes of hormones connected by non-covalent bonds with plasma proteins and formed elements. The degree of binding of various hormones varies greatly and is determined by their solubility in blood plasma and the presence of a transport protein. For example, 90% of cortisol, 98% of testosterone and estradiol, 96% of triiodothyronine and 99% of thyroxine bind to transport proteins. The bound form of the hormone cannot interact with receptors and forms a reserve that can be quickly mobilized to replenish the free hormone pool.

free form hormone- a physiologically active substance in the blood plasma in a protein-free state, capable of interacting with receptors. The bound form of the hormone is in dynamic equilibrium with the pool of free hormone, which in turn is in equilibrium with the hormone bound to receptors in target cells. Most polypeptide hormones, with the exception of somatotropin and oxytocin, circulate in low concentrations in the blood in a free state, without binding to proteins.

Metabolic transformations of the hormone - its chemical modification in target tissues or other formations, causing a decrease / increase in hormonal activity. The most important place for the exchange of hormones (their activation or inactivation) is the liver.

Hormone metabolism rate - the intensity of its chemical transformation, which determines the duration of circulation in the blood. The half-life of catecholamines and polypeptide hormones is several minutes, and that of thyroid and steroid hormones is from 30 minutes to several days.

hormone receptor- a highly specialized cellular structure that is part of the plasma membranes, cytoplasm or nuclear apparatus of the cell and forms a specific complex compound with the hormone.

The organ specificity of the action of the hormone - responses of organs and tissues to physiologically active substances; they are strictly specific and cannot be called by other compounds.

Feedback- the influence of the level of circulating hormone on its synthesis in endocrine cells. A long feedback chain is the interaction of the peripheral endocrine gland with the pituitary, hypothalamic centers and with the suprahypothalamic regions of the central nervous system. A short feedback chain - a change in the secretion of the pituitary tron ​​hormone, modifies the secretion and release of statins and liberins of the hypothalamus. An ultrashort feedback chain is an interaction within an endocrine gland in which the secretion of a hormone affects the secretion and release of itself and other hormones from that gland.

Negative feedback - an increase in the level of the hormone, leading to inhibition of its secretion.

positive feedback- an increase in the level of the hormone, which causes stimulation and the appearance of a peak of its secretion.

Anabolic hormones - physiologically active substances that promote the formation and renewal of the structural parts of the body and the accumulation of energy in it. These substances include pituitary gonadotropic hormones (follitropin, lutropin), sex steroid hormones (androgens and estrogens), growth hormone (somatotropin), placental chorionic gonadotropin, and insulin.

Insulin- a protein substance produced in β-cells of the islets of Langerhans, consisting of two polypeptide chains (A-chain - 21 amino acids, B-chain - 30), which reduces blood glucose levels. The first protein whose primary structure was completely determined by F. Sanger in 1945-1954.

catabolic hormones- physiologically active substances that contribute to the breakdown of various substances and structures of the body and the release of energy from it. These substances include corticotropin, glucocorticoids (cortisol), glucagon, high concentrations of thyroxine and adrenaline.

Thyroxine (tetraiodothyronine) - an iodine-containing derivative of the amino acid tyrosine, produced in the follicles of the thyroid gland, which increases the intensity of basal metabolism, heat production, which affects the growth and differentiation of tissues.

Glucagon - a polypeptide produced in a-cells of the islets of Langerhans, consisting of 29 amino acid residues, stimulating the breakdown of glycogen and increasing blood glucose levels.

Corticosteroid hormones - compounds formed in the adrenal cortex. Depending on the number of carbon atoms in the molecule, they are divided into C 18 -steroids - female sex hormones - estrogens, C 19 -steroids - male sex hormones - androgens, C 21 -steroids - corticosteroid hormones proper, which have a specific physiological effect.

Catecholamines - derivatives of pyrocatechin, actively involved in physiological processes in the body of animals and humans. The catecholamines include epinephrine, norepinephrine, and dopamine.

Sympathoadrenal system - chromaffin cells of the adrenal medulla and the preganglionic fibers of the sympathetic nervous system innervating them, in which catecholamines are synthesized. Chromaffin cells are also found in the aorta, carotid sinus, and within and near the sympathetic ganglia.

Biogenic amines- a group of nitrogen-containing organic compounds formed in the body by decarboxylation of amino acids, i.e. cleavage from them of the carboxyl group - COOH. Many of the biogenic amines (histamine, serotonin, norepinephrine, adrenaline, dopamine, tyramine, etc.) have a pronounced physiological effect.

Eicosanoids - physiologically active substances, predominantly derivatives of arachidonic acid, which have a variety of physiological effects and are divided into groups: prostaglandins, prostacyclins, thromboxanes, levuglandins, leukotrienes, etc.

Regulatory peptides- macromolecular compounds, which are a chain of amino acid residues connected by a peptide bond. Regulatory peptides with up to 10 amino acid residues are called oligopeptides, from 10 to 50 - polypeptides, more than 50 - proteins.

Antihormone- a protective substance produced by the body with prolonged administration of protein hormonal preparations. The formation of an antihormone is an immunological reaction to the introduction of a foreign protein from outside. In relation to its own hormones, the body does not form antihormones. However, substances similar in structure to hormones can be synthesized, which, when introduced into the body, act as antimetabolites of hormones.

Hormone antimetabolites- physiologically active compounds that are similar in structure to hormones and enter into competitive, antagonistic relationships with them. Antimetabolites of hormones are able to take their place in the physiological processes occurring in the body, or block hormone receptors.

Tissue hormone (autocoid, local hormone) - a physiologically active substance produced by non-specialized cells and having a predominantly local effect.

Neurohormone- a physiologically active substance produced by nerve cells.

The effector hormone a physiologically active substance that has a direct effect on cells and target organs.

throne hormone- a physiologically active substance that acts on other endocrine glands and regulates their functions.

Characteristics of the endocrine system

General physiology of the endocrine glands

The value of the activity of sensory systems in sports

The effectiveness of performing sports exercises depends on the perception and processing of sensory information. These processes determine both the most rational organization of motor acts and the perfection of the athlete's tactical thinking.

Endocrine glands enter the system humoral regulation of body functions together with a system of local self-regulation. Local self-regulation manifests itself in the action on neighboring cells of tissue hormones (histamine, serotonin, kinins and prostaglandins) and metabolic products (lactate).

Features of the endocrine glands:

Substances are isolated that have a significant (even in very small concentrations) and specialized effects on the metabolism, structure and function of organs and tissues.

They differ from the glands of external secretion in that they secrete the substances they produce directly into the blood, therefore they are called endocrine (endo - inside, krinen - secrete), and there are no external ducts.

They are small in size and mass, well supplied with blood vessels and braided with nerve fibers, since the activity of the endocrine glands is controlled by the nervous system.

All glands are functionally closely related to each other and the defeat of one of them leads to a violation of the functions of all the others.

Hormones - biologically active substances produced by the endocrine glands and secreted into the bloodstream in response to specific signals. Hormones have a relative species specificity, which made it possible at the early stages of their use to compensate for the lack of hormones in humans by administering preparations derived from animal tissues. Currently, many hormonal preparations are obtained synthetically, they are preferable to use, since they cause allergic reactions less often.

Functions of hormones:

1. Impact on processes differentiation(in a developing embryo);

2. Process regulation breeding- fertilization, egg implantation, pregnancy and lactation, differentiation and development of sperm and eggs;

3. Impact on growth and development: The optimal growth of children is due to the combined action of growth hormone, thyroid hormones, insulin, and the presence of inadequate amounts of insulin antagonists or sex steroids can inhibit growth.

4. Security adaptation(short-term and long-term) to changing environmental conditions, the quantity and quality of food consumed, external physical, chemical, biological and psychological influences;

5. Participation in the regulation of the rate of aging (for example, aging accompanied by a decrease in the secretion of sex hormones).

General properties of hormones:

1. Electoral action on sensitive cells: hormones increase or decrease the activity of cells that respond to them, which are called target cells. On the target cells are receptors - special protein molecules that recognize this hormone and interact with it. As a result of such interaction with the receptor, the hormone triggers a sequence of reactions in the target cell, which lead to a specific cellular response.

Such a response includes the acceleration of some biochemical processes with the simultaneous inhibition of others. The influence of peptide hormones and amino acid derivatives (adrenaline, norepinephrine) is carried out by binding to receptors on the surface of cell membranes, and steroid hormones and thyroid hormones penetrate into the cell, bind to the receptor in the cytoplasm, and then, in combination with the receptor, penetrate into the nucleus.

2. secretion rate of some hormones is associated with the wake-sleep cycle, the secretion of other hormones depends on age, sex, etc.

3. Information transmission systems. As soon as the hormone begins to act on a cell or group of cells that is sensitive to it, a signal simultaneously appears that inhibits the action of this hormone. This principle is called "feedback". Preservation of the required level of the hormone in the blood is supported by the mechanism negative feedback (i.e., with an excess of a hormone or substances formed under its action, the secretion of this hormone decreases, and with a deficiency, it increases).

4. Time of action.

Hormones of a peptide nature (hormones of the pituitary gland, pancreas, hypothalamic neuropeptides) have a duration of action from several seconds to minutes.

Hormones in the form of proteins and glycoproteins (growth hormone) - from several minutes to hours.

- Steroids (sex and corticosteroids) - a few hours.

- Iodthyronines (thyroid hormones) - several days.