Thyroxine Triiodothyronine Androgen Glucocorticoids

Estrogens

In turn, the release of all 7 of these hormones of the adenohypophysis depends on the hormonal activity of neurons in the pituitary zone of the hypothalamus - mainly the paraventricular nucleus (PVN). Hormones are formed here that have a stimulating or inhibitory effect on the secretion of adenohypophysis hormones. Stimulants are called releasing hormones (liberins), inhibitors are called statins. Thyroid-releasing hormone and gonadoliberin were isolated. somatostatin, somatoliberin, prolactostatin, prolactoliberin, melanostatin, melanoliberin, corticoliberin.

Releasing hormones are released from the processes of nerve cells of the paraventricular nucleus, enter the portal venous system of the hypothalamo-pituitary gland and are transported with the blood to the adenohypophysis.

The regulation of the hormonal activity of most endocrine glands is carried out according to the principle of negative feedback: the hormone itself, its amount in the blood, regulates its formation. This effect is mediated through the formation of the corresponding releasing hormones (Fig. 6,7)

In the hypothalamus (supraoptic nucleus), in addition to releasing hormones, vasopressin (antidiuretic hormone, ADH) and oxytocin are synthesized. Which in the form of granules are transported along the nerve processes to the neurohypophysis. The release of hormones into the bloodstream by neuroendocrine cells is due to reflex nerve stimulation.

Rice. 7 Direct and feedback connections in the neuroendocrine system.

1 - slowly developing and long-lasting inhibition of the secretion of hormones and neurotransmitters , as well as behavior change and memory formation;

2 - rapidly developing but long-lasting inhibition;

3 - short-term inhibition

Pituitary hormones

The posterior lobe of the pituitary gland, the neurohypophysis, contains oxytocin and vasopressin (ADH). ADH affects three types of cells:

1) renal tubular cells;

2) smooth muscle cells of blood vessels;

3) liver cells.

In the kidneys, it promotes the reabsorption of water, which means preserving it in the body, reducing diuresis (hence the name antidiuretic), in blood vessels it causes contraction of smooth muscles, narrowing their radius, and as a result, increases blood pressure (hence the name “vasopressin”), in liver - stimulates gluconeogenesis and glycogenolysis. In addition, vasopressin has an antinociceptive effect. ADH is designed to regulate the osmotic pressure of the blood. Its secretion increases under the influence of such factors: increased blood osmolarity, hypokalemia, hypocalcemia, increased decrease in blood volume, decreased blood pressure, increased body temperature, activation of the sympathetic system.

If ADH secretion is insufficient, diabetes insipidus develops: the volume of urine excreted per day can reach 20 liters.

Oxytocin in women plays the role of a regulator of uterine activity and is involved in lactation processes as an activator of myoepithelial cells. An increase in oxytocin production occurs during dilation of the cervix at the end of pregnancy, ensuring its contraction during childbirth, as well as during feeding of the baby, ensuring milk secretion.

The anterior lobe of the pituitary gland, or adenohypophysis, produces thyroid-stimulating hormone (TSH), somatotropic hormone (GH) or growth hormone, gonadotropic hormones, adrenocorticotropic hormone (ACTH), prolactin, and in the middle lobe - melanocyte-stimulating hormone (MSH) or intermedia.

A growth hormone stimulates protein synthesis in bones, cartilage, muscles and liver. In an immature organism, it ensures growth in length by increasing the proliferative and synthetic activity of cartilage cells, especially in the growth zone of long tubular bones, while simultaneously stimulating the growth of the heart, lungs, liver, kidneys and other organs. In adults, it controls the growth of organs and tissues. STH reduces the effects of insulin. Its release into the blood increases during deep sleep, after muscle exertion, and during hypoglycemia.

The growth effect of growth hormone is mediated by the hormone’s effect on the liver, where somatomedins (A, B, C) or growth factors are formed, which cause the activation of protein synthesis in cells. The value of growth hormone is especially great during the period of growth (prepubertal, pubertal periods).

During this period, GH agonists are sex hormones, an increase in the secretion of which contributes to a sharp acceleration of bone growth. However, prolonged formation of large quantities of sex hormones leads to the opposite effect - to the cessation of growth. An insufficient amount GH leads to dwarfism (nanism), and excessive GH leads to gigantism. Growth of some adult bones may resume if there is excessive secretion of GH. Then the proliferation of cells in the germ zones resumes. What causes growth

In addition, glucocorticoids inhibit all components of the inflammatory reaction - they reduce capillary permeability, inhibit exudation, and reduce the intensity of phagocytosis.

Glucocorticoids sharply reduce the production of lymphocytes, reduce the activity of T-killers, the intensity of immunological surveillance, hypersensitivity and sensitization of the body. All this allows us to consider glucocorticoids as active immunosuppressants. This property is used clinically to stop autoimmune processes and to reduce the host’s immune defense.

Glucocorticoids increase sensitivity to catecholamines and increase secretion of hydrochloric acid and pepsin. An excess of these hormones causes bone demineralization, osteoporosis, loss of Ca 2+ in the urine, and reduces Ca 2+ absorption. Glucocorticoids affect the function of the internal nervous system - they increase the activity of information processing and improve the perception of external signals.

Mineralocorticoids(aldosgerone, deoxycorticosterone) are involved in the regulation of mineral metabolism. The mechanism of action of aldosterone is associated with the activation of protein synthesis involved in the reabsorption of Na + - Na +, K h -ATPase. By increasing reabsorption and reducing it for K + in the distal tubules of the kidney, salivary and gonads, aldosterone promotes the retention of Na and SG in the body and the removal of K + and H from the body. Thus, aldosterone is a sodium-sparing and also a kaliuretic hormone. Due delay of Ia\ and, after it, water, it contributes to an increase in blood volume and, as a result, an increase in blood pressure.Unlike glucocorticoids, mineralocorticoids contribute to the development of inflammation, because they increase capillary permeability.

Sex hormones The adrenal glands perform the function of developing the genital organs and the appearance of secondary sexual characteristics during the period when the gonads are not yet developed, that is, in childhood and in old age.

The hormones of the adrenal medulla - adrenaline (80%) and norepinephrine (20%) - cause effects that are largely identical to the activation of the nervous system. Their action is realized through interaction with a- and beta-adrenergic receptors. Consequently, they are characterized by activation of the heart, constriction of skin vessels, dilation of the bronchi, etc. Adrenaline affects carbohydrate and fat metabolism, enhancing glycogenolysis and lipolysis.

Catecholamines are involved in the activation of thermogenesis, in the regulation of the secretion of many hormones - they increase the release of glucagon, renin, gastrin, parathyroid hormone, calcitonin, thyroid hormones; reduce insulin release. Under the influence of these hormones, the performance of skeletal muscles and the excitability of receptors increase.

With hyperfunction of the adrenal cortex in patients, secondary sexual characteristics noticeably change (for example, in women, male sexual characteristics may appear - a beard, mustache, timbre of voice). Obesity (especially in the neck, face, and torso), hyperglycemia, water and sodium retention in the body, etc. are observed.

Hypofunction of the adrenal cortex causes Addison's disease - a bronze tint of the skin (especially the face, neck, hands), loss of appetite, vomiting, increased sensitivity to cold and pain, high susceptibility to infections, increased diuresis (up to 10 liters of urine per day), thirst, decreased performance.

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Hormonal regulation of puberty. Carries out humoral regulation of vital processes In men and women, the function of the gonads is under the control of neurohumoral regulation, which ensures the coordination of neuronal (Latin nervus - nerve) and humoral (Latin humor - fluid) phenomena (the release of certain fluids to nerve stimuli). One of mandatory conditions their functioning is the normal activity of the cerebral appendage (pituitary gland). The secretion and release of hormones into the blood occur under the control of special centers located in the hypothalamus. Human sex life also depends on the cerebral cortex. Nervous regulation of sexual function. It is carried out by the genital centers, which are located in the lumbar and sacral segments of the spinal cord, the hypothalamus and the cerebral cortex. These centers are directly (humorally) and indirectly (by fibers of the autonomic nervous system) connected to the genitals, endocrine glands and to each other. Before puberty, the main active center of nervous regulation is the spinal cord (sacral segments). With the onset of active functioning of the anterior lobe of the pituitary gland and the hormone-producing cells of the gonads, the remaining nerve centers (lumbar segments of the spinal cord, midbrain and cerebral cortex) are activated. However, if, due to dysfunction, the pituitary gland is unable to produce gonadotropic hormones that stimulate the genital organs, as a result of which more advanced nerve centers begin to function, sexual development does not occur. The regulatory function of the genital centers, which are located in the sacral segments of the spinal cord, is carried out according to the type of unconditioned reflexes; centers in the lumbar segments of the spinal cord and in the midbrain - unconditional; cortical centers- conditional. Endocrine regulation of sexual function. Specific endocrine regulation of the functions of the genital organs is provided by the pituitary-gonadal system. The pituitary gland secretes gonadotropic hormones, under the influence of which sex hormones are produced in the gonads. The sensitivity of the genital Centers, the development and excitability of the genital organs depend on them. Visual, auditory, olfactory, and tactile signals pass through the cerebral cortex and are transformed in the hypothalamus, causing the synthesis of its hormones, which enter the pituitary gland and stimulate the production of other hormones. Hormones are released directly into the bloodstream and are transported through the bloodstream to the tissues on which they act. The most important hormone affecting sexual function is testosterone. It is also called the male sex hormone, although it is also found in much smaller quantities in women. The body of a healthy man produces 6 - 8 mg of testosterone per day (more than 95% is produced by the testes, the rest by the adrenal glands). A woman's testicles and adrenal glands produce approximately 0.5 mg of it every day. Testosterone is the main biological factor, determines sexual desire in men and women. An insufficient amount of it leads to a decrease in sexual activity, and an excess of it increases sexual desire. In men, testosterone levels that are too low can make it difficult to achieve and maintain an erection. in women - causes a decrease in libido. There is no evidence that, in general, women’s interest in sex is lower compared to men due to less testosterone in their blood. There is an opinion that the threshold of sensitivity of men and WOMEN to its action is different, with women being more sensitive to less of it in the blood. Estrogens (Greek oistros - passion and genos - birth) (mainly estradiol), which are also called female sex hormones, are also found in men. In women they are produced in the ovaries, in men - in the testicles. The female body needs them to maintain the normal state of the vaginal mucosa and the production of vaginal secretions. Estrogens also help preserve the structure and function of a woman’s mammary glands and the elasticity of her vagina. However, they do not significantly affect a woman's interest in sex or her sexual performance, since surgical removal of the ovaries does not reduce sexual desire women and their sexual activity. The function of estrogen in men has not yet been sufficiently studied. However, their level that is too high in men sharply reduces sexual activity and can cause difficulty in erection and enlargement of the mammary glands. In both men and women it is also progesterone (Latin pro - prefix, means one who acts in the interests of whom, what, and gestatio - pregnancy) - a hormone similar in structure to estrogens and androgens. It is assumed that its high level has an inhibitory effect on human sexual activity and restrains it. So, the neurohumoral regulation of sexual function is ensured by the activity of the deep structures of the brain and the endocrine system, which form the expression of sexual desire and excitation of all parts of the nervous system that affect sexual life. Nervous regulation carried out using electrical impulses traveling along nerve cells. Compared to humoral it happens faster more accurate requires a lot of energy more evolutionarily young. Humoral regulation vital processes (from the Latin word humor - “liquid”) are carried out due to substances secreted in internal environment body (lymph, blood, tissue fluid). Humoral regulation can be carried out with the help of: hormones- biologically active (acting in very small concentrations) substances secreted into the blood by glands internal secretion; other substances. For example, carbon dioxide causes local expansion of capillaries, more blood flows to this place; stimulates the respiratory center of the medulla oblongata, breathing intensifies. All glands of the body are divided into 3 groups 1) Endocrine glands ( endocrine) do not have excretory ducts and secrete their secretions directly into the blood. The secretions of the endocrine glands are called hormones, they have biological activity (act in microscopic concentration). For example: . 2) Exocrine glands have excretory ducts and secrete their secretions NOT into the blood, but into some cavity or onto the surface of the body. For example, liver, tearful, salivary, sweaty. 3) Mixed secretion glands carry out both internal and external secretion. For example the gland secretes insulin and glucagon into the blood, and not into the blood (into the duodenum) - pancreatic juice; sexual glands secrete sex hormones into the blood, and not into the blood - germ cells. Establish a correspondence between the organ (organ department) involved in the regulation of the vital functions of the human body and the system to which it belongs: 1) nervous, 2) endocrine. A) bridge B) pituitary gland B) pancreas D) spinal cord D) cerebellum Answer Establish the sequence in which the humoral regulation of respiration occurs during muscular work in the human body 1) accumulation of carbon dioxide in tissues and blood 2) excitation of the respiratory center in the medulla oblongata 3) impulse transmission to the intercostal muscles and diaphragm 4) increased oxidative processes during active muscle work 5) inhalation and air flow into the lungs Answer Establish a correspondence between the process that occurs during human breathing and the method of its regulation: 1) humoral, 2) nervous A) excitation of nasopharyngeal receptors by dust particles B) slowing down breathing when immersed in cold water C) change in breathing rhythm with excess carbon dioxide in the room D) difficulty breathing when coughing D) a change in breathing rhythm when the carbon dioxide content in the blood decreases Answer 1. Establish a correspondence between the characteristics of the gland and the type to which it is classified: 1) internal secretion, 2) external secretion. Write numbers 1 and 2 in the correct order. A) have excretory ducts B) produce hormones C) provide regulation of all vital functions of the body D) secrete enzymes into the stomach cavity D) excretory ducts exit to the surface of the body E) produced substances are released into the blood Answer 2. Establish a correspondence between the characteristics of the glands and their type: 1) external secretion, 2) internal secretion. Write numbers 1 and 2 in the correct order. A) form digestive enzymes B) secrete secretions into the body cavity C) release chemically active substances - hormones D) participate in the regulation of vital processes of the body D) have excretory ducts Answer Establish a correspondence between the glands and their types: 1) external secretion, 2) internal secretion. Write numbers 1 and 2 in the correct order. A) pineal gland B) pituitary gland B) adrenal gland D) salivary D) liver E) pancreatic cells that produce trypsin Answer Establish a correspondence between the example of regulation of the heart and the type of regulation: 1) humoral, 2) nervous A) increased heart rate under the influence of adrenaline B) changes in heart function under the influence of potassium ions B) change in heart rate under the influence of the autonomic system D) weakening of heart activity under the influence of the parasympathetic system Answer Establish a correspondence between the gland in the human body and its type: 1) internal secretion, 2) external secretion A) dairy B) thyroid B) liver D) sweat D) pituitary gland E) adrenal glands Answer 1. Establish a correspondence between the sign of regulation of functions in the human body and its type: 1) nervous, 2) humoral. Write numbers 1 and 2 in the correct order. A) delivered to organs by blood B) high response speed B) is more ancient D) is carried out with the help of hormones D) is associated with the activity of the endocrine system Answer 2. Establish a correspondence between the characteristics and types of regulation of body functions: 1) nervous, 2) humoral. Write numbers 1 and 2 in the order corresponding to the letters. A) turns on slowly and lasts a long time B) the signal propagates through the structures of the reflex arc B) is carried out by the action of a hormone D) the signal travels through the bloodstream D) turns on quickly and has a short duration E) evolutionarily more ancient regulation Answer Choose the one that suits you best correct option. Which of the following glands secrete their products through special ducts into the cavities of the body organs and directly into the blood? 1) greasy 2) sweat 3) adrenal glands 4) sexual Answer Establish a correspondence between the gland of the human body and the type to which it belongs: 1) internal secretion, 2) mixed secretion, 3) external secretion A) pancreas B) thyroid B) lacrimal D) greasy D) sexual E) adrenal gland Answer Choose three options. In what cases is humoral regulation carried out? 1) excess carbon dioxide in the blood 2) the body's reaction to a green traffic light 3) excess glucose in the blood 4) the reaction of the body to a change in the position of the body in space 5) release of adrenaline during stress Answer Establish a correspondence between examples and types of breathing regulation in humans: 1) reflex, 2) humoral. Write numbers 1 and 2 in the order corresponding to the letters. A) stop breathing on inspiration when entering cold water B) an increase in the depth of breathing due to an increase in the concentration of carbon dioxide in the blood C) cough when food enters the larynx D) slight holding of breath due to a decrease in the concentration of carbon dioxide in the blood D) change in breathing intensity depending on the emotional state E) cerebral vascular spasm due to a sharp increase in oxygen concentration in the blood Answer Select three endocrine glands. 1) pituitary gland 2) sexual 3) adrenal glands 4) thyroid 5) stomach 6) dairy Answer Choose three options. Humoral effects on physiological processes in the human body 1) carried out using chemically active substances 2) associated with the activity of the exocrine glands 3) spread more slowly than nervous ones 4) occur with the help of nerve impulses 5) controlled by the medulla oblongata 6) carried out through the circulatory system Answer Choose three correct answers out of six and write down the numbers under which they are indicated. What is characteristic of the humoral regulation of the human body? 1) the response is clearly localized 2) the signal is a hormone 3) turns on quickly and acts instantly 4) signal transmission is only chemical through body fluids 5) signal transmission occurs through the synapse 6) the response lasts for a long time Answer © D.V. Pozdnyakov, 2009-2019 Anatomical and physiological features of puberty and the tasks of educational hygiene Anatomical and physiological features of brain maturation. psychophysical aspects of child behavior The chromosome sets of male and female bodies differ in that women have two X chromosomes, and men have one X and one Y chromosome. This difference determines the sex of the embryo and occurs at the moment of fertilization. Already in the embryonic period, the development of the reproductive system completely depends on the activity of hormones. The activity of sex chromosomes is observed during a very short period of ontogenesis - from the 4th to the 6th week of intrauterine development and is manifested only in the activation of the testes. There are no differences in the differentiation of other body tissues between boys and girls, and if not for the hormonal influence of the testes, development would proceed only according to the female type. The female pituitary gland works cyclically, which is determined by hypothalamic influences. In men, the pituitary gland functions evenly. It has been established that there are no sex differences in the pituitary gland itself; they are contained in the nervous tissue of the hypothalamus and adjacent nuclei of the brain. In the period between the 8th and 12th weeks of intrauterine development, the testis must “form” the hypothalamus according to male type with the help of androgens. If this does not happen, the fetus will continue to have a cyclic type of gonadotropin secretion, even if it has a male set of XY chromosomes. Therefore, the use of sex steroids by a pregnant woman in the initial stages of pregnancy is very dangerous. Boys are born with well-developed excretory cells of the testes (Leydig cells), which, however, degrade in the 2nd week after birth. They begin to develop again only during puberty. This and some other facts suggest that reproductive system a person is, in principle, ready for development at the time of birth, however, under the influence of specific neurohumoral factors, this process is inhibited for several years - until the onset of pubertal changes in the body. Newborn girls sometimes experience a reaction from the uterus, appearing bloody issues similar to menstrual ones, and the activity of the mammary glands is also noted, up to the secretion of milk. A similar reaction of the mammary glands occurs in newborn boys. In the blood of newborn boys, the content of the male hormone testosterone is higher than in girls, but already a week after birth, this hormone is almost not detected in either boys or girls. However, after a month in boys, the level of testosterone in the blood increases rapidly again, reaching 4-7 months. half the level of an adult male, and remains at this level for 2-3 months, after which it decreases slightly and does not change until the onset of puberty. What causes this infantile release of testosterone is unknown, but there is an assumption that during this period some very important “male” properties are formed. The process of puberty proceeds unevenly, and it is customary to divide it into certain stages, at each of which specific relationships develop between the nervous and endocrine regulatory systems. The English anthropologist J. Tanner called these stages stages, and research by domestic and foreign physiologists and endocrinologists made it possible to establish what morphofunctional properties are characteristic of the body at each of these stages. Zero stage- newborn stage. This stage is characterized by the presence of preserved maternal hormones in the child’s body, as well as a gradual regression of the activity of the child’s own endocrine glands after the birth stress ends. First stage- stage of childhood (infantilism). The period from a year before the appearance of the first signs of puberty is regarded as the stage of sexual infantilism, i.e. it is understood that nothing happens during this period. However, minor and gradual increase secretion of hormones from the pituitary gland and gonads occurs during this period, and this indirectly indicates the maturation of the diencephalic structures of the brain. The development of the gonads during this period does not occur because it is inhibited by the gonadotropin-inhibiting factor, which is produced by the pituitary gland under the influence of the hypothalamus and another brain gland - the pineal gland. Starting from the age of 3, girls are ahead of boys in terms of physical development, and this is combined with a higher level of growth hormone in their blood. Immediately before puberty, the secretion of growth hormone increases even more, and this causes an acceleration of growth processes - a prepubertal growth spurt. The external and internal genitalia develop inconspicuously, and there are no secondary sexual characteristics. This stage ends for girls at 8-10 years old, and for boys at 10-13 years old. Although boys grow slightly slower than girls at this stage, the longer duration of the stage results in boys being larger than girls when they enter puberty. Second stage- pituitary (beginning of puberty). By the beginning of puberty, the formation of the gonadotropin inhibitor decreases, and the pituitary gland secretes two important gonadotropic hormones that stimulate the development of the gonads - follitropin and lutropin. As a result, the glands “wake up” and active synthesis of testosterone begins. At this moment, the sensitivity of the gonads to pituitary influences increases significantly, and effective feedback is gradually established in the hypothalamic-pituitary-gonadal system. In girls, during this same period, the concentration of growth hormone is highest; in boys, the peak of growth activity is observed later. The first external sign of the onset of puberty in boys is the enlargement of the testicles, which occurs under the influence of gonadotropic hormones of the pituitary gland. At the age of 10, these changes can be noticed in a third of boys, at 11 - in two thirds, and by 12 years - in almost all. In girls, the first sign of puberty is swelling of the mammary glands, and often the left gland begins to enlarge a little earlier. At first, the glandular tissue can only be palpated, then the isola is protruded. The deposition of adipose tissue and the formation of a mature gland occurs in subsequent stages of puberty. This stage of puberty ends at 11-12 years old for boys, and at 9-10 years old for girls. Third stage- stage of gonadal activation. At this stage, the effect of pituitary hormones on the gonads intensifies, and the gonads begin to produce large quantities ah sex steroid hormones. At the same time, the gonads themselves enlarge: in boys this is clearly noticeable by a significant increase in the size of the testicles. In addition, under the combined influence of growth hormone and androgens, boys become greatly elongated in length, and the penis also grows, almost reaching adult size by the age of 15. High concentration female sex hormones - estrogens - in boys during this period can lead to swelling of the mammary glands, expansion and increased pigmentation of the nipple and areola area. These changes are short-lived and usually resolve without intervention within a few months of their onset. At this stage, both boys and girls experience intense hair growth in the pubis and armpits. This stage ends for girls at 10-11 years old, and for boys at 12-16 years old. Fourth stage- stage of maximum steroidogenesis. The activity of the gonads reaches a maximum, the adrenal glands synthesize a large amount of sex steroids. In boys it persists high level growth hormone, so they continue to grow rapidly; in girls, growth processes slow down. Primary and secondary sexual characteristics continue to develop: pubic and axillary hair growth increases, and the size of the genitals increases. In boys, it is at this stage that a mutation (break) of the voice occurs. Fifth stage- stage of final formation. Physiologically, this period is characterized by the establishment of a balanced feedback between pituitary hormones and peripheral glands. This stage begins in girls at 11-13 years old, in boys - at 15-17 years old. Ticket 1. 1. Factors of nonspecific resistance of the organism Nonspecific protective factors are congenital, have specific characteristics, and are inherited. Animals with reduced resistance adapt poorly to any changes in OS and are susceptible to both infectious and non-infectious diseases. The following factors protect the body from any foreign agent. Histohematic barriers- these are barriers formed nearby biological membranes between blood and tissues. These include: the blood-brain barrier (between the blood and the brain), the hematothymic barrier (between the blood and the thymus), the placental barrier (between the mother and the fetus), etc. They protect the organs from those agents that nevertheless penetrate the blood through the skin or mucous membranes. Phagocytosis is the process of absorption of foreign particles by cells and their digestion. Phagocytes include microphages and macrophages. Microphages are granulocytes; the most active phagocytes are neutrophils. Light and mobile, neutrophils are the first to rush towards the stimulus, absorb and break down foreign particles with their enzymes, regardless of their origin and properties. Eosinophils and basophils have weakly expressed phagocytic activity. Macrophages include blood monocytes and tissue macrophages - wandering or fixed in certain areas. Phagocytosis proceeds in 5 phases. 1. Positive chemotaxis - active movement of phagocytes towards chemical stimuli. 2. Adhesion - adhesion of a foreign particle to the surface of a phagocyte. A restructuring of the receptor molecules occurs, they come closer and concentrate, then the contractile mechanisms of the cytoskeleton are launched, and the phagocyte membrane seems to float onto the object. 3. Formation of a phagosome - drawing a particle surrounded by a membrane into the phagocyte. 4. Formation of a phagolysosome - the fusion of a lysosome of a phagocyte with a phagosome. Digestion of a foreign particle, that is, its enzymatic cleavage 5. Removing unnecessary products from the cage. Lysozyme is an enzyme that hydrolyzes the glycosidic bonds of polyamino sugars in the shells of many sugars. The result of this is damage to the membrane structure and the formation of defects (large pores) in it, through which water penetrates into the microbial cell and causes its lysis. Lysozyme is synthesized by neutrophils and monocytes; it is found in blood serum and in the secretions of exocrine glands. Very high concentrations of lysozyme in saliva, especially in dogs, and in tear fluid. B-lysines. These are the enzymes that activate the dissolution cell membranes, including m / o, their own enzymes. B-lysines are formed during the destruction of platelets during blood clotting; they are found in high concentrations in blood serum. Complement system. It includes: complement, properdin and magnesium ions. Properdin is a protein complex that has antimicrobial and antiviral activity, but it does not act in isolation, but in combination with magnesium and complement, activating and enhancing its effect. Complement (“supplement”) is a group of blood proteins that have enzymatic activity and interact with each other according to the type of cascade reaction, that is, the first activated enzymes activate enzymes next row by splitting them into fragments, these fragments also have enzymatic activity, therefore the number of participants in the reaction increases like an avalanche (cascade). Complement components are designated by the Latin letter C and serial numbers - C1, C2, C3, etc. Complement components are synthesized by tissue macrophages in the liver, skin, intestinal mucosa, as well as by vascular endothelium and neutrophils. They are constantly in the blood, but in an inactive state, and their content does not depend on the introduction of the antigen. Activation of the complement system can be carried out in two ways - classical and alternative. The classical pathway of activation of the first component of the system (C1) requires the mandatory presence of antigen + antigen immune complexes in the blood. It's fast and effective way. An alternative activation pathway occurs in the absence of immune complexes, then the surfaces of cells and bacteria become the activator. Starting with the activation of the S3 component, the general path of subsequent reactions is launched, which ends with the formation of a membrane attack complex - a group of enzymes that ensure lysis (dissolution) of the object of enzymatic attack. Properdin and magnesium ions are involved in the activation of S3, a key component of complement. The C3 protein binds to the microbial cell membrane. M/o carrying activated S3 on the surface are easily absorbed and destroyed by phagocytes. In addition, the released complement fragments attract other participants to the site of the reaction - neutrophils, basophils and mast cells. The value of the complement system: 1 - enhances the AG + AT connection, adhesion and phagocytic activity of phagocytes, that is, it promotes opsonization of cells, prepares them for subsequent lysis; 2 - promotes the dissolution (lysis) of immune complexes and their removal from the body; 3 - participates in inflammatory processes (release of histamine from mast cells, local hyperemia, increased vascular permeability), in blood coagulation processes (destruction of platelets and release of platelet-derived coagulation factors). Interferons are substances of antiviral protection. They are synthesized by some lymphocytes, fibroblasts, cells connective tissue. Interferons do not destroy viruses, but, when formed in infected cells, they bind to nearby receptors, healthy cells. Next, intracellular enzyme systems are turned on, blocking the synthesis of proteins and their own cells and viruses => the source of infection is localized and does not spread to healthy tissue. Thus, nonspecific resistance factors are constantly present in the body, they act regardless of the specific properties of antigens, they do not increase when the body comes into contact with foreign cells or substances. This is a primitive, ancient way of protecting the body from foreign substances. It is not “remembered” by the body. Although many of these factors are also involved in the body’s immune response, the mechanisms of complement or phagocyte activation are nonspecific. Thus, the mechanism of phagocytosis is nonspecific; it does not depend on the individual properties of the agent, but is carried out against any foreign particle. Also lysozyme: its physiological significance lies in regulating the permeability of body cells by destroying polysaccharide complexes of cell membranes, and not a reaction to microbes. In system preventive measures In veterinary medicine, measures to increase the natural resistance of animals occupy an important place. They include proper, balanced nutrition, sufficient amounts of proteins, lipids, minerals and vitamins in the feed. Great importance In keeping animals, solar insolation, dosed physical activity, provision of good sanitary conditions, and relief from stressful situations are allotted. 2. Functional characteristics of the female reproductive system. Terms of sexual and physiological maturity of females. Follicular development, ovulation and formation of the corpus luteum. The reproductive cycle and the factors that determine it. 72 Female reproductive cells are formed in the ovaries, and hormones necessary for the reproductive processes are synthesized here. By the time of puberty, females have a large number of developing follicles in the cortical layer of the ovaries. The development of follicles and eggs is a cyclical process. One or more follicles and, accordingly, one or more eggs develop simultaneously. Stages of follicle development: The primary follicle consists of a germ cell (a first-order oocyte), a single layer of follicular cells surrounding it and a connective tissue membrane - the theca; The secondary follicle is formed as a result of the proliferation of follicular cells, which at this stage surround the germ cell in several layers; Graafian vesicle - in the center of such a follicle there is a fluid-filled cavity, surrounded by a zone of follicular cells arranged in 10-12 layers. Of the growing follicles, only a part develops completely. Most of them die on different stages development. This phenomenon is called follicular atresia. This process is a physiological phenomenon necessary for the normal course of cyclic processes in the ovaries. After maturation, the follicle wall ruptures, and the egg in it, along with the follicular fluid, enters the oviduct funnel. The process of releasing an egg from a follicle is called ovulation. It is currently believed that ovulation is associated with certain biochemical and enzymatic processes in the follicle wall. Before ovulation, the amount of hyaluronidase and proteolytic enzymes increases in the follicle, which take a significant part in the lysis of the follicle membrane. Hyaluronidase synthesis occurs under the influence of LH. After ovulation, the egg enters the cavity through the funnel of the oviduct. There are reflex and spontaneous ovulation. reflex ovulation characteristic of cats and rabbits. In these animals, rupture of the follicle and release of the egg occurs only after sexual intercourse (or less often, after strong sexual arousal). Spontaneous ovulation does not require completed sexual intercourse; rupture of the follicle occurs when it reaches a certain degree of maturity. Spontaneous ovulation is typical for cows, goats, mares, dogs. After the release of the egg with the cells of the corona radiata, the cavity of the follicles is filled with blood from the ruptured vessels. The cells of the follicle membrane begin to multiply and gradually replace the blood clot, forming corpus luteum. There are cyclic corpus luteum and corpus luteum of pregnancy. The corpus luteum is a temporary endocrine gland. Its cells secrete progesterone, as well as (especially, but in the second half of pregnancy) relaxin. Sexual cycle The sexual cycle should be understood as a set of structural and functional changes occurring in the reproductive apparatus and the entire body of the female from one ovulation to the next. The period of time from one ovulation (estrus) to the next is the duration of the sexual cycle. Animals in which sexual cycles are repeated frequently throughout the year (in the absence of pregnancy) are called polycyclic (cows, pigs). Monocyclic animals are those animals in which the sexual cycle occurs only once or twice during the year (for example, cats, foxes). Sheep are an example of polycyclic animals with a pronounced sexual season; they have several sexual cycles one after another, after which there is no cyclicity for a long time. The English researcher Hipp, based on the morphofunctional changes occurring in the female reproductive apparatus, identified the following stages of the sexual cycle: - proestrus (precursor)- the beginning of rapid growth of follicles. Developing follicles produce estrogens. Under their influence, the blood supply to the genital organs was increased, and the vaginal mucosa acquired a reddish color. Its cells become keratinized. The secretion of mucus by the cells of the mucous membrane of the vagina and cervix increases. The uterus enlarges, its mucous membrane becomes full of blood and the uterine glands become active. At this time, bitches experience bloody discharge from the vagina. - Estrus (heat)- sexual arousal occupies a dominant position. The animal tends to mate and allows cage. The blood supply to the genital apparatus and the secretion of mucus are enhanced. The cervical canal relaxes, which leads to mucus flowing out of it (hence the name “estrus”). The growth of the follicle ends and ovulation occurs - its rupture and the release of the egg. - Metestrus (after-leak)- epithelial cells opened follicles turn into luteal, formed yellow body. Blood vessels grow in the wall of the uterus, and the activity of the uterine glands increases. The cervical canal is closed. Reduced blood flow to the external genitalia. Sexual hunting stops. - Diestrus - the last stage of the sexual cycle. Dominance of the corpus luteum. The uterine glands are active, the cervix is ​​closed. There is little cervical mucus. The vaginal mucosa is pale. - Anestrus - a long period of sexual rest, during which ovarian function is weakened. Characteristic of monocyclic animals and animals with a pronounced sexual season in the period between cycles. Follicle development does not occur during this period. The uterus is small and anemic, its cervix is ​​tightly closed. The vaginal mucosa is pale. Russian scientist Studentsov proposed another classification of stages of the reproductive cycle, reflecting the characteristics of the state of the nervous system and behavioral reactions of females. According to Student's views, the sexual cycle is a manifestation of the vital activity of the entire organism as a whole, and not just the reproductive system. This process includes the following stages: - excitement stage characterized by the presence of four phenomena: estrus, sexual (general) arousal of the female, heat and ovulation. Excitation stage begins with follicle maturation. The process of ovulation completes the arousal stage. Ovulation in mares, sheep and pigs occurs a few hours after the start of heat, and in cows (unlike females of other species) 11-26 hours after the extinction of the immobility reflex. You can count on successful insemination of the female only during the arousal stage. - braking stage- during this period, there is a weakening and complete cessation of estrus and sexual arousal. In the reproductive system, involutionary processes predominate. The female no longer reacts to the male or other females in heat (unresponsiveness); in place of the ovulated follicles, corpus luteum begins to develop, which secrete the pregnancy hormone progesterone. If fertilization does not occur, then the processes of proliferation and secretion that began during the period of estrus gradually stop. - balancing stage- during this period of the sexual cycle there are no signs of estrus, hunting and sexual arousal. This stage is characterized by a balanced state of the animal, the presence of both corpus luteum and follicles in the ovary. Approximately two weeks after ovulation, the secretory activity of the corpus luteum ceases in the absence of pregnancy. The processes of follicle maturation are activated again and a new sexual cycle begins. Neurohumoral regulation female sexual functions Excitation of sexual processes occurs through the nervous system and its highest department - the cerebral cortex. Signals about the action of external and internal stimuli are received there. From there, impulses enter the hypothalamus, whose neurosecretory cells secrete specific neurosecrets (releasing factors). The latter affect the pituitary gland, which as a result releases gonadotropic hormones: FSH, LH and LTG. The entry into the blood of FSH determines the growth, development and maturation of follicles in the ovaries. Maturing follicles produce follicular (estrogenic) hormones, which cause estrus in animals. The most active estrogen is estradiol. Under the influence of estrogen, the uterus enlarges, the epithelium of its mucous membrane expands, swells, and the secretion of all gonads increases. Estrogens stimulate contractions of the uterus and fallopian tubes, increasing their sensitivity to oxytocin, breast development, and metabolism. As estrogen accumulates, their effect on the nervous system increases, which causes sexual arousal and hunting in animals. Estrogens in large quantities affect the pituitary-hypothalamus system (as a negative connection), as a result of which the secretion of FSH is inhibited, but at the same time the release of LH and LTG increases. Under the influence of LH in combination with FSH, ovulation occurs and the formation of the corpus luteum, the function of which is supported by LH. The resulting corpus luteum produces the hormone progesterone, which determines the secretory function of the endometrium and prepares the uterine mucosa for implantation of the embryo. Progesterone helps maintain variability in animals at the initial stage, inhibits the growth of follicles and ovulation, and prevents uterine contraction. A high concentration of progesterone (by the principle of a negative connection) inhibits further release of LH, while stimulating (by a type of positive connection) the secretion of FSH, as a result of which new follicles are formed and the sexual cycle is repeated. For the normal manifestation of sexual processes, hormones of the pineal gland, adrenal glands, thyroid and other glands are also necessary. 3. Skin analyzer 109 PERCEPTION APPARATUS: four types of reception in the skin - heat, cold, tactile, pain. CONDUCTION PATHWAYS: segmental afferent nerves - spinal cord - medulla oblongata - thalamus - subcortical nuclei- bark. CENTRAL PART: bark cerebral hemispheres(coincides with the motor zones). Temperature reception . Krause flasks perceive low temperature, papillary brushes by Ruffini , Golgi-Mazzoni bodies - high. Cold receptors are located more superficially. Tactile reception. Taurus Vater-Pacini, Merkel, Meissner - perceive touch and pressure (touch). Pain reception. Free nerve endings. They do not have an adequate stimulus: the sensation of pain occurs with any type of stimulus, if it is strong enough or causes a metabolic disorder in the skin and the accumulation of metabolic products in it (histamine, serotonin, etc.). The skin analyzer has high sensitivity (the horse distinguishes between touches different points skin at a very short distance; the difference in temperature can be determined as 0.2ºС), contrast , adaptation (animals do not feel the harness or collar). Ticket 3. 1. Physiological characteristics of water-soluble vitamins. Water-soluble vitamins - C, P, B vitamins. Sources of water-soluble vitamins: green food, sprouted grains, shells and germs of seeds, cereals, legumes, yeast, potatoes, pine needles, milk and colostrum, eggs, liver. Most water-soluble vitamins in the body of farm animals are synthesized by the microflora of the gastrointestinal tract VITAMIN C- ascorbic acid, anti-scorbutic vitamin. Meaning: factor of nonspecific resistance of the body (stimulation of immunity); participation in the metabolism of proteins (especially collagen) and carbohydrates, in oxidative processes, in hematopoiesis. Regulation of capillary permeability. For hypovitaminosis C: scurvy - bleeding and fragility of capillaries, tooth loss, disruption of all metabolic processes. VITAMIN P- citrine. Meaning: acts together with vitamin C, regulates capillary permeability and metabolism. VITAMIN B₁- thiamine, antineurological vitamin. Meaning: part of enzymes that decarboxylate keto acids; A particularly important function of thiamine is metabolism in nervous tissue and in the synthesis of acetylcholine. With hypovitaminosis B₁ dysfunction nerve cells and nerve fibers (polyneuritis), exhaustion, muscle weakness. VITAMIN B 2- riboflavin. Meaning: metabolism of carbohydrates, proteins, oxidative processes, functioning of the nervous system, gonads. Hypovitaminosis- in birds, pigs, less often - horses. Slow growth, weakness, paralysis. VITAMIN B₃- pantothenic acid. Meaning: constituent of coenzyme A (CoA). Participates in fat metabolism, carbohydrate, protein. Activates acetic acid. Hypovitaminosis- in chickens, piglets. Growth retardation, dermatitis, movement coordination disorder. VITAMIN B4- choline. Meaning: part of lecithins, participates in fat metabolism, in the synthesis of acetylcholine. For hypovitaminosis- fatty liver degeneration. VITAMIN B 5- PP, nicotinic acid, antipellagritic . Meaning: part of the coenzyme of dehydrogenases that catalyze OVR. Stimulates the secretion of parasitic juices, heart function, and hematopoiesis. Hypovitaminosis- in pigs and birds: dermatitis, diarrhea, dysfunction of the cerebral cortex - pellagra. VITAMIN B 6- pyridoxine - adermin. Meaning: participation in protein metabolism - transamination, decarboxylation of AMK. Hypovitaminosis- in pigs, calves, birds: dermatitis, convulsions, paralysis. VITAMIN B₉- folic acid. Meaning: participation in hematopoiesis (together with vitamin B 12), in fat and protein metabolism. For hypovitaminosis- anemia, growth retardation, fatty liver. VITAMIN H- biotin, anti-seborrheic vitamin . Meaning: participation in carboxylation reactions. Hypovitaminosis biotin: dermatitis, profuse excretion sebum(seborrhea). VITAMIN B 12- cyanocobalamin. Meaning: erythropoiesis, synthesis of hemoglobin, NK, methionine, choline; stimulates protein metabolism. Hypovitaminosis- in pigs, dogs, birds: impaired hematopoiesis and anemia, disorder of protein metabolism, accumulation of residual nitrogen in the blood. VITAMIN B 15- pangamic acid. Meaning: strengthening OVR, preventing fatty infiltration of the liver. PABC- para-aminobenzoic acid. Meaning: part of vitamin B c - folic acid. ANTIVITAMINS- substances similar in chemical composition to vitamins, but having the opposite, antagonistic effect and competing with vitamins in biological processes. 2. Bile formation and bile excretion. Composition of bile and its importance in the digestive process. Regulation of bile secretion The formation of bile in the liver is continuous. In the gallbladder, some salts and water are reabsorbed from the bile, as a result of which a thicker, more concentrated, so-called gallbladder bile (pH 6.8) is formed from the liver bile (pH 7.5). It consists of mucus secreted by the cells of the mucous membrane of the gallbladder. Composition of bile: inorganic substances - sodium, potassium, calcium, bicarbonates, phosphates, water; organic matter - bile acids (glycocholic, taurocholic, lithocholic), bile pigments (bilirubin, biliverdin), fats, fatty acids, phospholipids, cholesterol, amino acids, urea. There are no enzymes in bile! Regulation of biliary excretion- complex reflex and neurohumoral. Parasympathetic nerves- contraction of the smooth muscles of the gallbladder and relaxation of the sphincter of the bile duct, resulting in the excretion of bile. Sympathetic nerves - contraction of the bile duct sphincter and relaxation of the gallbladder muscles. Accumulation of bile in the gallbladder. Stimulates bile excretion- food intake, especially fatty foods, irritation of the vagus nerve, cholecystokinin, secretin, acetylcholine, bile itself. Bile meaning: emulsification of fats, enhancing the action of digestive enzymes, formation of water-soluble complexes bile acids with fatty acids and their absorption; increased intestinal motility; excretory function (bile pigments, cholesterol, heavy metal salts); disinfection and deodorization, neutralization of hydrochloric acid, activation of prosecretin. 3. Transfer of excitation from the nerve to the working organ. Synapses and their properties. Mediators and their role 87 The point of contact of the axon with another cell - nerve or muscle - is called synapse. The membrane covering the axon terminal is called presynaptic. The part of the membrane of the second cell located opposite the axon is called postsynaptic. Between them - synaptic cleft. At neuromuscular synapses, to transmit excitation from the axon to the muscle fiber, chemical substances are used - mediators (intermediaries) - acetylcholine, norepinephrine, adrenaline, etc. At each synapse, one mediator is produced, and the synapses are called by the name of the mediator cholinergic or adrenergic. The presynaptic membrane contains vesicles, in which mediator molecules accumulate. On the postsynaptic membrane there are molecular complexes called receptors(not to be confused with receptors - sensitive nerve endings). The structure of the receptor includes molecules that “recognize” the mediator molecule and an ion channel. There is also a macroergic substance - ATP, and the enzyme ATPase, which stimulates the breakdown of ATP to provide energy for excitation. After performing its function, the transmitter must be destroyed, and hydrolytic enzymes are built into the postsynaptic membrane: acetylcholinesterase, or cholinesterase, which destroys acetylcholine and monoamine oxidase, which destroys norepinephrine. 2. The hypothalamic-pituitary system as the main mechanism of neurohumoral regulation of hormone secretion. 3. Pituitary hormones 5. Parathyroid hormones 6. Pancreatic hormones 7. The role of hormones in the body’s adaptation to stress factors Humoral regulation- this is a type of biological regulation in which information is transmitted using biologically active substances that are carried throughout the body by blood, lymph, and intercellular fluid. Humoral regulation differs from nervous regulation: information carrier - a chemical substance (for nervous - nerve impulse, PD); transmission of information is carried out by blood flow, lymph, by diffusion (with nervous - nerve fibers); the humoral signal travels more slowly (with blood flow in the capillaries - 0.05 mm/s) than the nervous signal (up to 120-130 m/s); the humoral signal does not have such a precise “addressee” (the nervous signal is very specific and precise), affecting those organs that have receptors for the hormone. Factors of humoral regulation: "classical" hormones Hormones of the APUD system Classic hormones themselves- these are substances synthesized by endocrine glands. These are hormones of the pituitary gland, hypothalamus, pineal gland, adrenal glands; pancreas, thyroid, parathyroid, thymus, gonads, placenta (Fig. I). In addition to the endocrine glands, in various organs and tissues there are specialized cells that release substances that act on target cells through diffusion, i.e., entering the body locally. These are paracrine hormones. These include neurons of the hypothalamus, which produce some hormones and neuropeptides, as well as cells of the APUD system, or the system for capturing amine precursors and their decarboxylation. Examples include: liberins, statins, hypothalamic neuropeptides; interstinal hormones, components of the renin-angiotensin system. 2) Tissue hormones secreted by unspecialized cells of various types: prostaglandins, enkephalins, components of the kallikrein-inin system, histamine, serotonin. 3) Metabolic factors- these are nonspecific products that are formed in all cells of the body: lactic acid, pyruvic acid, CO 2, adenosine, etc., as well as decomposition products during intense metabolism: increased content of K +, Ca 2+, Na +, etc. Functional meaning hormones: 1) ensuring growth, physical, sexual, intellectual development; 2) participation in the adaptation of the body in various changing conditions of the external and internal environment; 3) maintaining homeostasis.. Rice. 1 Endocrine glands and their hormones Properties of hormones: 1) specificity of action; 2) distant nature of the action; 3) high biological activity. 1. The specificity of action is ensured by the fact that hormones interact with specific receptors located in certain target organs. As a result, each hormone acts only on specific physiological systems or organs. 2. Distance lies in the fact that the target organs on which hormones act are, as a rule, located far from the place of their formation in the endocrine glands. Unlike “classical” hormones, tissue hormones act paracrine, that is, locally, not far from the place of their formation. Hormones act in very small quantities, which is where their high biological activity. Thus, the daily requirement for an adult is: thyroid hormones - 0.3 mg, insulin - 1.5 mg, androgens - 5 mg, estrogens - 0.25 mg, etc. The mechanism of action of hormones depends on their structure Hormones of protein structure Hormones of steroid structure Rice. 2 Mechanism of hormonal control Hormones of protein structure (Fig. 2) interact with receptors of the plasma membrane of the cell, which are glycoproteins, and the specificity of the receptor is determined by the carbohydrate component. The result of the interaction is the activation of protein phosphokinases, which provide phosphorylation of regulatory proteins, transfer of phosphate groups from ATP to hydroxyl groups of serine, threonine, tyrosine, protein. The final effect of these hormones can be a reduction, enhancement of enzymatic processes, for example, glycogenolysis, increased protein synthesis, increased secretion, etc. The signal from the receptor with which the protein hormone interacts is transmitted to the protein kinase with the participation of a specific intermediary or second messenger. Such messengers can be (Fig. 3): 1) cAMP; 2) Ca 2+ ions; 3) diacylglycerol and inositol triphosphate; 4) other factors. Fig.Z. The mechanism of membrane reception of the hormonal signal in the cell with the participation of second messengers. Hormones with a steroid structure (Fig. 2) easily penetrate into the cell through plasma membrane due to their lipophilicity, they interact in the cytosol with specific receptors, forming a “hormone-receptor” complex that moves into the nucleus. In the nucleus, the complex disintegrates and hormones interact with nuclear chromatin. As a result of this, interaction with DNA occurs, and then induction of messenger RNA. Due to the activation of transcription and translation 2-3 hours after exposure to the steroid, increased synthesis of induced proteins is observed. In one cell, the steroid affects the synthesis of no more than 5-7 proteins. It is also known that in the same cell, a steroid hormone can cause induction of the synthesis of one protein and repression of the synthesis of another protein (Fig. 4). The action of thyroid hormones is carried out through receptors in the cytoplasm and nucleus, as a result of which the synthesis of 10-12 proteins is induced. Reflation of hormone secretion is carried out by the following mechanisms: 1) direct influence of blood substrate concentrations on gland cells; 2) nervous regulation; 3) humoral regulation; 4) neurohumoral regulation (hypothalamic-pituitary system). In the regulation of the activity of the endocrine system, the principle of self-regulation, which is carried out according to the type of feedback, plays an important role. There are positive (for example, an increase in blood sugar leads to an increase in insulin secretion) and negative feedback (with an increase in the level of thyroid hormones in the blood, the production of thyroid-stimulating hormone and thyrotropin-releasing hormone, which ensure the release of thyroid hormones, decreases). So, the direct influence of the concentrations of blood substrates on gland cells occurs according to the principle of feedback. If the level of a substance controlled by a specific hormone changes in the blood, then “the tear responds by increasing or decreasing the secretion of this hormone. Nervous regulation carried out due to the direct influence of the sympathetic and parasympathetic nerves on the synthesis and secretion of hormones (neurohypophysis, adrenal medulla), as well as indirectly, “changing the intensity of the blood supply to the gland. Emotional, mental influences through the structures of the limbic system, through the hypothalamus, can significantly influence the production of hormones. Hormonal regulation It is also carried out according to the principle of feedback: if the level of a hormone in the blood increases, then the release of those hormones that control the content of this hormone decreases, which leads to a decrease in its concentration in blood. For example, when the level of cortisone in the blood increases, the release of ACTH (a hormone that stimulates the secretion of hydrocortisone) decreases and, as a consequence, Decrease in its level in the blood. Another example of hormonal regulation could be this: melatonin (pineal gland hormone) modulates the function of the adrenal glands, thyroid gland, gonads, i.e. a certain hormone can influence the content of other hormonal factors in the blood. The hypothalamic-pituitary system as the main mechanism of neurohumoral regulation of hormone secretion. The function of the thyroid, gonads, and adrenal cortex is regulated by hormones of the anterior pituitary gland - the adenohypophysis. Here they are synthesized tropic hormones: adrenocorticotropic (ACTH), thyroid-stimulating (TSH), follicle-stimulating (FS) and luteinizing (LH) (Fig. 5). With some convention, triple hormones also include somatotropic hormone (growth hormone), which affects growth not only directly, but also indirectly through hormones - somatomedins, formed in the liver. All these tropic hormones are so named due to the fact that they ensure the secretion and synthesis of the corresponding hormones of other endocrine glands: ACTH - glucocorticoids and mineralocorticoids: TSH - thyroid hormones; gonadotropic - sex hormones. In addition, intermedia (melanocyte-stimulating hormone, MCH) and prolactin are formed in the adenohypophysis, which have an effect on peripheral organs.

Humoral regulation ensures longer adaptive reactions of the human body. Factors of humoral regulation include hormones, electrolytes, mediators, kinins, prostaglandins, various metabolites, etc.

The highest form of humoral regulation is hormonal. The term “hormone” comes from Greek and means “to stimulate action,” although not all hormones have a stimulating effect.

Hormones - these are biologically highly active substances synthesized and released into the internal environment of the body by the endocrine glands, or endocrine glands, and causing a regulatory effect on the functions of organs and systems of the body remote from the place of their secretion, endocrine gland - This is an anatomical formation, devoid of excretory ducts, the sole or main function of which is the internal secretion of hormones. The endocrine glands include the pituitary gland, pineal gland, thyroid gland, adrenal glands (medulla and cortex), and parathyroid glands (Fig. 2.9). Unlike internal secretion, external secretion is carried out by the exocrine glands through the excretory ducts into the external environment. In some organs both types of secretion are present simultaneously. To the organs with mixed type secretions include the pancreas and gonads. The same endocrine gland can produce hormones that differ in their action. For example, thyroid produces thyroxine and thyrocalcitonin. At the same time, the production of the same hormones can be carried out by different endocrine glands.

The production of biologically active substances is a function not only of the endocrine glands, but also of other traditionally non-endocrine organs: kidneys, gastrointestinal tract, heart. Not all substances formed

specific cells of these organs, satisfy the classical criteria of the concept of “hormones”. Therefore, along with the term “hormone” in Lately The concepts of hormone-like and biologically active substances (BAS) are also used ), topical hormones . For example, some of them are synthesized so close to their target organs that they can reach them by diffusion without entering the bloodstream.

Cells that produce such substances are called paracrine.

The chemical nature of hormones and biologically active substances is different. The duration of its biological action depends on the complexity of the structure of the hormone, for example, from fractions of a second for mediators and peptides to hours and days for steroid hormones and iodothyronines.

Hormones have the following basic properties:

Rice. 2.9 General topography of the endocrine glands:

1 – pituitary gland; 2 – thyroid gland; 3 – thymus gland; 4 – pancreas; 5 – ovary; 6 – placenta; 7 – testis; 8 – kidney; 9 – adrenal gland; 10 - parathyroid glands; 11 – pineal gland of the brain

1. Strict specificity of physiological action;

2. High biological activity: hormones exert their physiological effects in extremely small doses;

3. Distant nature of action: target cells are usually located far from the site of hormone production.

Inactivation of hormones occurs mainly in the liver, where they undergo various chemical changes.

Hormones perform the following important functions in the body:

1. Regulation of growth, development and differentiation of tissues and organs, which determines physical, sexual and mental development;

2. Ensuring the body’s adaptation to changing living conditions;

3. Ensuring the maintenance of the constancy of the internal environment of the body.

Regulation of the activity of the endocrine glands is carried out by nervous and humoral factors. The regulatory influence of the central nervous system on the activity of the endocrine glands is carried out through the hypothalamus. The hypothalamus receives signals from the external and internal environment through the afferent pathways of the brain. Neurosecretory cells of the hypothalamus transform afferent nerve stimuli into humoral factors.

The pituitary gland occupies a special position in the system of endocrine glands. The pituitary gland is spoken of as the “central” endocrine gland. This is due to the fact that the pituitary gland, through its special hormones, regulates the activity of other, so-called “peripheral” glands.

The pituitary gland is located at the base of the brain. The pituitary gland is a complex organ in its structure. It consists of anterior, middle and posterior lobes. The pituitary gland is well supplied with blood.

In the anterior lobe of the pituitary gland, somatotropic hormone, or growth hormone (somatotropin), prolactin, thyroid-stimulating hormone (thyrotropin), etc. are formed. Somatotropin takes part in the regulation of growth, which is due to its ability to enhance the formation of protein in the body. The most pronounced effect of the hormone is on bone and cartilage tissue. If the activity of the anterior lobe of the pituitary gland (hyperfunction) manifests itself in childhood, this leads to increased growth of the body in length - gigantism. When the function of the anterior lobe of the pituitary gland (hypofunction) decreases in a growing body, a sharp growth retardation occurs - dwarfism. Excessive production of the hormone in an adult does not affect the growth of the body as a whole, since it is already completed. Prolactin promotes the formation of milk in the alveoli of the mammary gland.

Thyrotropin stimulates thyroid function. Corticotropin is a physiological stimulator of the zona fasciculata and reticularis of the adrenal cortex, where glucocorticoids are formed.

Corticotropin causes breakdown and inhibits protein synthesis in the body. In this regard, the hormone is an antagonist of somatotropin, which enhances protein synthesis.

The middle lobe of the pituitary gland produces a hormone that affects pigment metabolism.

The posterior lobe of the pituitary gland is closely connected with the nuclei of the hypothalamic region. The cells of these nuclei are capable of forming substances of a protein nature. The resulting neurosecretion is transported along the axons of the neurons of these nuclei to the posterior lobe of the pituitary gland. The hormones oxytocin and vasopressin are produced in the nerve cells of the nuclei.

Or vasopressin, performs two functions in the body. The first function is associated with the influence of the hormone on the smooth muscles of arterioles and capillaries, the tone of which it increases, which leads to an increase in blood pressure. The second and main function is related to, expressed in its ability to enhance the reabsorption of water from the kidney tubules into the blood.

The pineal body (epiphysis) is an endocrine gland, which is a cone-shaped formation located in the diencephalon. In appearance, the gland resembles a fir cone.

The pineal gland produces primarily serotonin and melatonin, as well as norepinephrine and histamine. Peptide hormones and biogenic amines were found in the pineal gland. The main function of the pineal gland is the regulation of daily biological rhythms, endocrine functions and metabolism, and the body’s adaptation to changing light conditions. Excess light inhibits the conversion of serotonin to melatonin and promotes the accumulation of serotonin and its metabolites. In the dark, on the contrary, melatonin synthesis increases.

The thyroid gland consists of two lobes located in the neck on either side of the trachea below the thyroid cartilage. The thyroid gland produces iodine-containing hormones - thyroxine (tetraiodothyronine) and triiodothyronine. There is more thyroxine in the blood than triiodothyronine. However, the activity of the latter is 4-10 times higher than that of thyroxine. The human body has a special hormone, thyrocalcitonin, which is involved in the regulation of calcium metabolism. Under the influence of thyrocalcitonin, the level of calcium in the blood decreases. The hormone inhibits the removal of calcium from bone tissue and increases its deposition in it.

There is a relationship between the iodine content in the blood and the hormone-forming activity of the thyroid gland. Small doses of iodine stimulate, and large doses inhibit the processes of hormone formation.

The autonomic nervous system plays an important role in regulating the formation of hormones in the thyroid gland. Excitation of its sympathetic department leads to an increase, and the predominance of parasympathetic tone causes a decrease in the hormone-forming function of this gland. Substances (neurosecretions) are formed in the neurons of the hypothalamus, which, when entering the anterior lobe of the pituitary gland, stimulate the synthesis of thyrotropin. When there is a lack of thyroid hormones in the blood, there is an increased formation of these substances in the hypothalamus, and when there is an excess content, their synthesis is inhibited, which in turn reduces the production of thyrotropin in the anterior pituitary gland.

The cerebral cortex also takes part in regulating the activity of the thyroid gland.

The secretion of thyroid hormones is regulated by the iodine content in the blood. With a lack of iodine in the blood, as well as iodine-containing hormones, the production of thyroid hormones increases. When there is an excess amount of iodine in the blood and thyroid hormones, a negative feedback mechanism operates. Excitation of the sympathetic part of the autonomic nervous system stimulates the hormone-producing function of the thyroid gland, and excitation of the parasympathetic part inhibits it.

Disorders of the thyroid gland are manifested by its hypofunction and hyperfunction. If insufficiency of function develops in childhood, this leads to growth retardation, disturbance of body proportions, sexual and mental development. This pathological condition is called cretinism. In adults, hypofunction of the thyroid gland leads to the development of a pathological condition - myxedema. With this disease, inhibition of neuropsychic activity is observed, which manifests itself in lethargy, drowsiness, apathy, decreased intelligence, decreased excitability of the sympathetic part of the autonomic nervous system, impaired sexual function, inhibition of all types of metabolism and a decrease in basal metabolism. In such patients, body weight is increased due to an increase in the amount of tissue fluid and facial puffiness is noted. Hence the name of this disease: myxedema - mucous swelling.

Hypofunction of the thyroid gland can develop in people living in areas where there is a lack of iodine in the water and soil. This is the so-called endemic goiter. The thyroid gland in this disease is enlarged (goiter), however, due to a lack of iodine, few hormones are produced, which leads to corresponding disturbances in the body, manifested in the form of hypothyroidism.

With hyperfunction of the thyroid gland, the disease thyrotoxicosis develops (diffuse toxic goiter, Basedow's disease, Graves' disease). Characteristic signs of this disease are an enlargement of the thyroid gland (goiter), increased metabolism, especially the basal one, loss of body weight, increased appetite, disturbance of the body's thermal balance, increased excitability and irritability.

Parathyroid glands- paired organ. A person has two pairs of parathyroid glands, located on the posterior surface or buried inside the thyroid gland.

The parathyroid glands are well supplied with blood. They have both sympathetic and parasympathetic innervation.

The parathyroid glands produce parathyroid hormone (parathyrin). From the parathyroid glands, the hormone enters directly into the blood. Parathyroid hormone regulates calcium metabolism in the body and maintains a constant level of calcium in the blood. With insufficiency of the parathyroid glands (hypoparathyroidism), there is a significant decrease in the level of calcium in the blood. On the contrary, with increased activity of the parathyroid glands (hyperparathyroidism), an increase in the concentration of calcium in the blood is observed.

Skeletal bone tissue is the main depot of calcium in the body. Therefore, there is a certain relationship between the level of calcium in the blood and its content in bone tissue. Parathyroid hormone regulates the processes of calcification and decalcification (deposition and release of calcium salts) in the bones. By influencing calcium metabolism, the hormone simultaneously affects phosphorus metabolism in the body.

The activity of these glands is determined by the level of calcium in the blood. There is an inverse relationship between the hormone-producing function of the parathyroid glands and the level of calcium in the blood. If the concentration of calcium in the blood increases, this leads to a decrease in the functional activity of the parathyroid glands. When the level of calcium in the blood decreases, the hormone-forming function of the parathyroid glands increases.

The thymus gland (thymus) is a paired lobular organ located in the chest cavity behind the sternum.

The thymus gland consists of two lobes of unequal size, connected to each other by a layer of connective tissue. Each lobe of the thymus gland includes small lobules, in which the cortex and medulla are distinguished. The cortex is represented by parenchyma, which contains a large number of lymphocytes. The thymus gland is well supplied with blood. It produces several hormones: thymosin, thymopoietin, thymic humoral factor. All of them are proteins (polypeptides). The thymus gland plays a large role in regulating the body's immune processes, stimulating the formation of antibodies, and controls the development and distribution of lymphocytes involved in immune reactions.

The thymus gland reaches its maximum development in childhood. After puberty, it stops developing and begins to atrophy. The physiological significance of the thymus gland is also that it contains a large amount of vitamin C, second only to the adrenal glands in this regard.

The pancreas is a mixed-function gland. As an exocrine gland, it produces pancreatic juice, which through excretory duct secreted into the cavity of the duodenum. The intrasecretory activity of the pancreas is manifested in its ability to produce hormones that come from the gland directly into the blood.

The pancreas is innervated by sympathetic nerves coming from the celiac (solar) plexus and branches of the vagus nerve. The islet tissue of the gland contains a large amount of zinc. Zinc is also a component of insulin. The gland has an abundant blood supply.

The pancreas secretes two hormones, insulin and glucagon, into the blood. Insulin takes part in the regulation of carbohydrate metabolism. Under the influence of the hormone, the concentration of sugar in the blood decreases - hypoglycemia occurs. If the blood sugar level is normally 4.45-6.65 mmol/l (80-120 mg%), then under the influence of insulin, depending on the dose administered, it becomes below 4.45 mmol/l. The decrease in blood glucose levels under the influence of insulin is due to the fact that the hormone promotes the conversion of glucose into glycogen in the liver and muscles. In addition, insulin increases the permeability of cell membranes to glucose. In this regard, there is an increased penetration of glucose into the cell, where it is utilized. The importance of insulin in the regulation of carbohydrate metabolism also lies in the fact that it prevents the breakdown of proteins and their conversion into glucose. Insulin stimulates protein synthesis from amino acids and their active transport into cells. It regulates fat metabolism, promoting the formation fatty acids from products of carbohydrate metabolism. Insulin inhibits the mobilization of fat from adipose tissue.

Insulin production is regulated by blood glucose levels. Hyperglycemia leads to an increase in the release of insulin into the blood. Hypoglycemia reduces the formation and flow of the hormone into the vascular bed. Insulin converts glucose into glycogen and blood sugar levels are restored to normal levels.

If the amount of glucose falls below normal and hypoglycemia occurs, then a reflexive decrease in the formation of insulin occurs.

Insulin secretion is regulated by the autonomic nervous system: stimulation of the vagus nerves stimulates the formation and release of the hormone, and sympathetic nerves inhibit these processes.

The amount of insulin in the blood depends on the activity of the enzyme insulinase, which destroys the hormone. The largest amounts of the enzyme are found in the liver and skeletal muscles. When blood flows through the liver once, insulinase destroys up to 50% of insulin.

Insufficiency of the intrasecretory function of the pancreas, accompanied by a decrease in insulin secretion, leads to a disease called diabetes mellitus. The main manifestations of this disease are: hyperglycemia, glucosuria (sugar in the urine), polyuria (increased urine output up to 10 liters per day), polyphagia ( increased appetite), polydipsia (increased thirst), resulting from loss of water and salts. In patients, not only carbohydrate metabolism is disrupted, but also the metabolism of proteins and fats.

Glucagon is involved in the regulation of carbohydrate metabolism. By the nature of its effect on carbohydrate metabolism, it is an insulin antagonist. Under the influence of glucagon, glycogen is broken down in the liver into glucose. As a result, the concentration of glucose in the blood increases. In addition, glucagon stimulates the breakdown of fat in adipose tissue.

The formation of glucagon is influenced by the amount of glucose in the blood. With an increased level of glucose in the blood, glucagon secretion is inhibited, and with a decrease, there is an increase. The formation of glucagon is also influenced by the hormone of the anterior pituitary gland - somatotropin; it increases cell activity, stimulating the formation of glucagon.

The adrenal glands are paired glands. They are located directly above the upper poles of the kidneys, surrounded by a dense connective tissue capsule and immersed in adipose tissue. The bundles of the connective capsule penetrate inside the gland, passing into the septa that divide the adrenal glands into two layers - the cortex and the medulla. The adrenal cortex consists of three zones: glomerular, fascicular and reticular.

The cells of the zona glomerulosa lie directly under the capsule and are collected into glomeruli. In the fascicular zone, cells are arranged in the form of longitudinal columns or bundles. All three zones of the adrenal cortex are not only morphologically separate structural formations, but also perform different physiological functions.

The adrenal medulla consists of tissue in which there are two types of cells that produce adrenaline and norepinephrine.

The adrenal glands are richly supplied with blood and innervated by sympathetic and parasympathetic nerves.

They are an endocrine organ that has vital important. Removal of both adrenal glands results in death. It has been shown that the adrenal cortex is vital.

Hormones of the adrenal cortex are divided into three groups:

1) glucocorticoids - hydrocortisone, cortisone and corticosterone;

2) mineralocorticoids - aldosterone, deoxycorticosterone;

3) sex hormones - androgens, estrogens, progesterone.

The formation of hormones occurs predominantly in one area of ​​the adrenal cortex. Thus, mineralocorticoids are produced in the cells of the zona glomerulosa, glucocorticoids - in the zona fasciculata, and sex hormones - in the reticularis.

According to their chemical structure, adrenal hormones are steroids. They are formed from cholesterol. Ascorbic acid is also required for the synthesis of adrenal hormones.

Glucocorticoids affect the metabolism of carbohydrates, proteins and fats. They stimulate the formation of glucose from proteins and the deposition of glycogen in the liver. Glucocorticoids are insulin antagonists in the regulation of carbohydrate metabolism: they delay the utilization of glucose in tissues, and in case of an overdose, an increase in the concentration of sugar in the blood and its appearance in the urine can occur.

Glucocorticoids cause the breakdown of tissue protein and prevent the incorporation of amino acids into proteins and thereby delay the formation of granulations and subsequent scar formation, which negatively affects wound healing.

Glucocorticoids are anti-inflammatory hormones, as they have the ability to inhibit the development of inflammatory processes, in particular, by reducing the permeability of vascular membranes.

Mineralocorticoids are involved in the regulation of mineral metabolism. In particular, aldosterone enhances the reabsorption of sodium ions in the renal tubules and reduces the reabsorption of potassium ions. As a result, the excretion of sodium in the urine decreases and the excretion of potassium increases, which leads to an increase in the concentration of sodium ions in the blood and tissue fluid and an increase in osmotic pressure.

Sex hormones of the adrenal cortex stimulate the development of the genital organs in childhood, that is, when the intrasecretory function of the gonads is still poorly developed. Sex hormones of the adrenal cortex determine the development of secondary sexual characteristics and the functioning of the genital organs. They also have an anabolic effect on protein metabolism, stimulating protein synthesis in the body.

An important role in the regulation of the formation of glucocorticoids in the adrenal cortex is played by adrenocorticotropic hormone of the anterior pituitary gland. The influence of corticotropin on the formation of glucocorticoids in the adrenal cortex is carried out according to the principle of direct and feedback connections: corticotropin stimulates the production of glucocorticoids, and the excess content of these hormones in the blood leads to inhibition of the synthesis of corticotropin in the anterior pituitary gland.

In addition to the pituitary gland, the hypothalamus is involved in the regulation of glucocorticoid formation. In the kernels anterior section The hypothalamus produces a neurosecretion that contains a protein factor that stimulates the formation and release of corticotropin. This factor, through the common circulatory system of the hypothalamus and pituitary gland, enters its anterior lobe and promotes the formation of corticotropin. Functionally, the hypothalamus, the anterior pituitary gland and the adrenal cortex are closely connected.

The formation of mineralocorticoids is influenced by the concentration of sodium and potassium ions in the body. An increased amount of sodium ions in the blood and tissue fluid or an insufficient content of potassium ions in the blood leads to inhibition of the secretion of aldosterone in the adrenal cortex, which causes increased excretion of sodium in the urine. With a lack of sodium ions in the internal environment of the body, the production of aldosterone increases, and as a result, the reabsorption of these ions in the renal tubules increases. Excessive concentration of potassium ions in the blood stimulates the formation of aldosterone in the adrenal cortex. The process of mineralocorticoid formation is influenced by the amount of tissue fluid and blood plasma. An increase in their volume leads to inhibition of aldosterone secretion, which is accompanied by increased release of sodium ions and associated water.

The adrenal medulla produces catecholamines: adrenaline and norepinephrine (the precursor of adrenaline in the process of its biosynthesis). Adrenaline functions as a hormone; it flows from the adrenal glands into the blood constantly. In some emergency conditions of the body (acute drop in blood pressure, blood loss, cooling of the body, hypoglycemia, increased muscle activity: emotions - pain, fear, rage), the formation and release of the hormone into the vascular bed increases.

Excitation of the sympathetic nervous system is accompanied by an increase in the flow of adrenaline and norepinephrine into the blood. These catecholamines enhance and prolong the effects of the sympathetic nervous system. Adrenaline has the same effect on organ functions and the activity of physiological systems as the sympathetic nervous system. Adrenaline has a pronounced effect on carbohydrate metabolism, increasing the breakdown of glycogen in the liver and muscles, resulting in an increase in blood glucose levels. It increases the excitability and contractility of the heart muscle, and also increases the heart rate. The hormone increases vascular tone, which increases blood pressure. However, on coronary vessels heart, blood vessels of the lungs, brain and working muscles, adrenaline has a vasodilating effect.

Adrenaline enhances the contractile effect of skeletal muscles, inhibits the motor function of the gastrointestinal tract and increases the tone of its sphincters.

Adrenaline is a so-called short-acting hormone. This is due to the fact that the hormone is quickly destroyed in the blood and tissues.

Norepinephrine, unlike adrenaline, acts as a mediator - a transmitter of excitation from nerve endings to the effector. Norepinephrine is also involved in the transmission of excitation in neurons of the central nervous system.

The secretory function of the adrenal medulla is controlled by the hypothalamic region of the brain, since the higher autonomic centers of the sympathetic nervous system are located in the posterior group of its nuclei. When the neurons of the hypothalamus are irritated, adrenaline is released from the adrenal glands and its content in the blood increases.

The cerebral cortex influences the flow of adrenaline into the vascular bed.

The release of adrenaline from the adrenal medulla can occur reflexively, for example, during muscular work, emotional excitement, cooling the body and other effects on the body. The release of adrenaline from the adrenal glands is regulated by blood sugar levels.

Hormones of the adrenal cortex are involved in the development of adaptive reactions of the body that arise when exposed to various factors(cooling, fasting, trauma, hypoxia, chemical or bacterial intoxication, etc.). In this case, the same type of nonspecific changes occur in the body, manifested primarily by the rapid release of corticosteroids, especially glucocorticoids under the influence of corticotropin.

Gonads (sex glands) ) - testes (testes) in men and ovaries in women - belong to the glands with a mixed function. Due to the exocrine function of these glands, male and female reproductive cells are formed - sperm and eggs. The intrasecretory function is manifested in the secretion of male and female sex hormones that enter the blood.

The development of the gonads and the release of sex hormones into the blood determines sexual development and maturation. Puberty in humans occurs at the age of 12-16 years. It is characterized by the full development of primary and appearance of secondary sexual characteristics.

Primary sexual characteristics are characteristics related to the structure of the gonads and genital organs.

Secondary sexual characteristics are characteristics related to the structure and function of various organs other than the genitals. In men, secondary sexual characteristics are facial hair, features of the distribution of hair on the body, a low voice, a characteristic body structure, characteristics of the psyche and behavior. In women, secondary sexual characteristics include the location of body hair, body structure, and development of the mammary glands.

Male sex hormones are formed in special cells of the testicles: testosterone and androsterone. These hormones stimulate the growth and development of the reproductive system, male secondary sexual characteristics and the appearance of sexual reflexes. Androgens (male sex hormones) are necessary for the normal maturation of male germ cells - sperm. In the absence of hormones, motile mature sperm are not formed. In addition, androgens contribute to more long-term preservation motor activity male reproductive cells. Androgens are also necessary for the manifestation of sexual instinct and the implementation of behavioral reactions associated with it.

Androgens have big influence on metabolism in the body. They increase protein formation in various tissues, especially muscles, reduce body fat, and increase basal metabolism.

In the female reproductive glands - the ovaries - estrogen is synthesized.

Estrogens promote the development of secondary sexual characteristics and the manifestation of sexual reflexes, and also stimulate the development and growth of the mammary glands.

Progesterone ensures the normal course of pregnancy.

The formation of sex hormones in the gonads is under the control of gonadotropic hormones of the anterior pituitary gland.

Nervous regulation of the functions of the gonads is carried out in a reflex way due to changes in the process of formation of gonadotropic hormones in the pituitary gland.

7. The expression “sexy type” is widely used. What needs and motivations are constantly present in such a person?

8. What is the difference between first love and love at first sight? Needs? Hormones? Structure of behavior?

9. Diogenes, a prominent representative of the Cynic school of philosophy, lived in a barrel; condemned those who cared about the beauty of clothing; masturbated in public; condemned those who use utensils when eating, denied patriotism. What can be said about the teaching of the cynics using the concept of “needs”?

10. Why did Natasha Rostova, Prince Andrei’s fiancée, try to run away with someone else? What are the motives for her behavior, if we look at them from a biological point of view?

11. What is the role of hormones in organizing needs; motivation; movements?

12. What is a “mental state”?

Dewsbury D. Animal behavior. Comparative aspects. M., 1981.

Zorina Z. A., Poletaeva I. I., Reznikova Z. I. Fundamentals of ethology and genetics of behavior. M., 1999.

McFarland D. Animal behavior. Psychobiology, ethology and evolution. M., 1988.

Simonov P.V. Motivated brain. M., 1987.

Simonov P.V. Emotional brain. M., 1981.

Tinbergen N. Animal behavior. M., 1978.

Chapter 3
Humoral system

A common part.Differences between nervous and humoral regulation. Functional division of humoral agents: hormones, pheromones, mediators and modulators.

Basic hormones and glands.Hypothalamic-pituitary system. Hypothalamic and pituitary hormones. Vasopressin and oxytocin. Peripheral hormones. Steroid hormones. Melatonin.

Principles of hormonal regulation.Hormonal signal transmission: synthesis, secretion, transport of hormones, their effect on target cells and inactivation. Polyvalency of hormones. Regulation by the negative feedback mechanism and its important consequence. Interaction of endocrine systems: direct connection, feedback, synergism, permissive action, antagonism. Mechanisms of hormonal influences on behavior.

Carbohydrate metabolism.The meaning of carbohydrates. Psychotropic effect of carbohydrates. The blood glucose level is the most important constant. Humoral influences on various stages of carbohydrate metabolism. Metabolic and hedonic function of carbohydrates.

A complex example of the psychotropic effect of hormones: premenstrual syndrome.The influence of contraceptives. The effect of excess salt in the diet. The influence of dietary carbohydrates. Effect of alcohol.

Humoral (“humor” – liquid) control of body functions is carried out by substances transported throughout the body with fluids, primarily blood. Blood and other fluids carry substances that enter the body from the external environment, in particular through diet, 37
A diet is not a food restriction, but everything that enters the body with food.

As well as substances produced inside the body - hormones.

Nervous control is carried out using impulses distributed along the processes of nerve cells. The convention of dividing into nervous and humoral mechanisms of regulation of functions is already manifested in the fact that a nerve impulse is transmitted from cell to cell using a humoral signal - molecules of a neurotransmitter are released at the nerve ending, which is a humoral factor.

Humoral and nervous systems of regulation are two aspects of a single system of neurohumoral regulation of integral functions of the body.

All body functions are under dual control: nervous and humoral. Absolutely all organs and tissues of the human body are under humoral influence, while nervous control is absent in two organs: the adrenal cortex and the placenta. This means that these two organs do not have nerve endings. However, this does not mean that the functions of the adrenal cortex and placenta are outside the sphere of nervous influences. As a result of the activity of the nervous system, the release of hormones that regulate the functions of the adrenal cortex and placenta changes.

Nervous and humoral regulation are equally important for the preservation of the organism as a whole, including in the organization of behavior. It should be emphasized once again that humoral and nervous regulation are not, strictly speaking, different regulatory systems. They represent two sides of a single neurohumoral system. The role and share of participation of each of the two systems is different for different functions and states of the body. But in the regulation of an integral function, both humoral and purely nervous influences are always present. The division into nervous and humoral mechanisms is due to the fact that either physical or chemical methods are used to study them. To study neural mechanisms, exclusively methods of recording electric fields are more often used. The study of humoral mechanisms is impossible without the use of biochemical methods.

3.1.1. Differences between nervous and humoral regulation

The two systems - nervous and humoral - differ in the following properties. First, neural regulation is goal-directed. The signal along the nerve fiber comes to a strictly defined place: to a certain muscle, or to another nerve center, or to a gland. The humoral signal, i.e. hormone molecules, spreads with the bloodstream throughout the body. Whether or not tissues and organs will respond to this signal depends on the presence in the cells of these tissues of a perceptive apparatus - molecular receptors (see section 3.3.1).

Secondly, the nerve signal is fast, it moves to another organ - another nerve cell, muscle cell, gland cell - at a speed of 7 to 140 m/s, delaying the switching at synapses for only 1 millisecond. Thanks to neural regulation, we can do something “in the blink of an eye.” The content of most hormones in the blood increases only a few minutes after stimulation, and reaches a maximum no earlier than 30 minutes, or even one hour. Hence, maximum effect The action of the hormone can be observed several hours after a single exposure to the body. Thus, the humoral signal is slow.

Third, the nerve signal is brief. Typically, the burst of impulses caused by a stimulus lasts no more than a fraction of a second. This is the so-called inclusion reaction. A similar burst of electrical activity in nerve nodes noted when the stimulus ceases - a switch-off reaction. The humoral system carries out slow tonic regulation, that is, it has a constant effect on the organs, maintaining their function in a certain state. This demonstrates the supporting function of humoral factors (see section 1.2.2). The level of the hormone can remain elevated throughout the duration of the stimulus, and, in some conditions, up to several months. Such a persistent change in the level of activity of the nervous system is characteristic, as a rule, of an organism with impaired functions.

The main differences between nervous regulation and humoral regulation are as follows: the nerve signal is purposeful; the nerve signal is fast; the nervous signal is brief.

Another difference, or rather a group of differences, between the two systems of regulation of functions is due to the fact that the study of the neural regulation of behavior is more attractive when conducting research on humans. The most popular method of recording electrical fields in humans is recording an electroencephalogram (EEG), i.e., electrical fields of the brain. Its use does not cause pain, whereas taking a blood test to study humoral factors is associated with pain. The fear that many people experience while waiting for a shot can and does influence some test results. When a needle is inserted into the body, there is a risk of infection. Such a danger is negligible when recording an EEG. Finally, EEG recording is more cost-effective. If the determination of biochemical parameters requires constant financial costs for the purchase of chemical reagents, then to conduct long-term and large-scale EEG studies, a large, but one-time financial investment is sufficient - to purchase an electroencephalograph.

As a result of all the above circumstances, the study of the humoral regulation of human behavior is carried out mainly in clinics, i.e. by-product therapeutic measures. Therefore, there is incomparably less experimental data on the participation of humoral factors in the organization of the holistic behavior of a healthy person than experimental data on nervous mechanisms. When studying psychophysiological data, this should be kept in mind - the physiological mechanisms underlying psychological reactions are not limited to EEG changes. In a number of cases EEG changes They only reflect mechanisms that are based on diverse, including humoral, processes. For example, interhemispheric asymmetry - differences in EEG recordings on the left and right half of the head - is based mainly on the action of sex hormones.

3.1.2. Functional division of humoral agents: hormones, pheromones, mediators and neuromodulators

The endocrine system is made up of endocrine glands - glands that synthesize biologically active substances and secrete (release) them into the internal environment (usually into the circulatory system), which distributes them throughout the body. The secretions of the endocrine glands are called hormones. Hormones are one of the groups of biologically active substances secreted in the body of humans and animals. These groups differ in the nature of secretion.

"Internal secretion" means that substances are secreted into the blood or other internal fluid; “exocrine” means that substances are secreted into the digestive tract or onto the surface of the skin.

In addition to internal secretion, there is also external secretion. This includes highlighting digestive enzymes V gastrointestinal tract and various substances with sweat, urine and feces. Along with metabolic products, biologically active substances specially synthesized in various tissues, called pheromones, are also released into the environment. They perform a signaling function in communication between members of the community. Pheromones, which are perceived by animals through smell and taste, carry information about the gender, age, and condition (fatigue, fear, illness) of the animal. Moreover, with the help of pheromones, individual recognition of one animal by another and even the degree of relatedness of two individuals occurs. Special role pheromones play in the early stages of maturation of the body, in infancy. In this case, pheromones of both mother and father are important. In their absence, the development of the newborn slows down and may be disrupted.

Pheromones cause certain reactions in other individuals of the same species, and chemicals secreted by animals of one species, but perceived by animals of another species, are called kairomones. Thus, in the animal community, pheromones perform the same function as hormones within the body. Because humans have a much weaker sense of smell than animals, pheromones play a lesser role in the human community than in the animal community. However, they influence human behavior, particularly interpersonal relationships (see section 7.4).

The humoral regulation of functions also involves substances that are not classified as hormones, i.e., agents of internal secretion, since they are not released into the circulatory or lymphatic systems - these are mediators (neurotransmitters). They stand out nerve ending into the synaptic cleft, transmitting signals from one neuron to another. Inside the synapse they disintegrate without entering the bloodstream. Among the substances secreted by tissues that are not classified as hormones, a group of neuromodulators, or local hormones, is distinguished. These substances do not spread with the bloodstream throughout the body, like true hormones, but act on a group of nearby cells, releasing into the intercellular space.

The difference between the types of humoral agents is a functional difference. The same chemical substance can act as a hormone, a pheromone, a neurotransmitter, and a neuromodulator.

It should be emphasized that the above division of secretion products into groups is called functional, since it is made according to a physiological principle. The same chemical can perform different functions by being released in different tissues. For example, vasopressin, secreted in the posterior pituitary gland, is a hormone. It, released at synapses in various brain structures, is a mediator in these cases. Dopamine, being a hypothalamic hormone, is released into the circulatory system connecting the hypothalamus with the pituitary gland, and, at the same time, dopamine is a mediator in many brain structures. Norepinephrine, secreted by the adrenal medulla into the systemic circulation, performs the functions of a hormone, secreted in synapses - a mediator. Finally, entering (in a not entirely clear way) into the intercellular space in some brain structures, it is a neuromodulator.

Many biologically active substances, although distributed with the bloodstream throughout the body, are not hormones, since they are not synthesized by specialized cells, but are metabolic products, i.e. they enter the circulatory system as a result of the breakdown of nutrients in the gastrointestinal tract tract. These are, first of all, numerous amino acids (glycine, GABA, tyrosine, tryptophan, etc.) and glucose. These simple chemical compounds influence various forms of behavior in humans and animals.

Thus, the basis of the system of humoral regulation of the functions of the human and animal body is hormones, i.e., biologically active substances that are synthesized by specialized cells, secreted into the internal environment, transported throughout the body with the bloodstream and change the functions of target tissues.

Hormones are biologically active substances synthesized by specialized cells, secreted into the internal environment, transported through the bloodstream throughout the body and changing the functions of target tissues.

The role of neurotransmitters and neuromodulators is not discussed and almost not mentioned in this book, since they are not systemic factors that organize behavior - they act at the point of contact of nerve cells, or in an area limited by several nerve cells. In addition, consideration of the role of neurotransmitters and neuromodulators would require a preliminary presentation of a number of biological disciplines.

3.2. Major hormones and glands

Data from studies of the endocrine system, i.e., the system of endocrine glands, obtained in recent years, allow us to say that the endocrine system “permeates” almost the entire body. Cells that secrete hormones are found in almost every organ, the main function of which has long been known to be unrelated to the endocrine gland system. Thus, hormones of the heart, kidneys, lungs and numerous hormones of the gastrointestinal tract were discovered. The number of hormones found in the brain is so large that the volume of research on the secretory function of the brain is now comparable to the volume of electrophysiological studies of the central nervous system. This led to the joke: “The brain is not just an endocrine organ,” reminding researchers that the main function of the brain is, after all, the integration of many body functions into whole system. Therefore, only the main endocrine glands and the central endocrine unit of the brain will be described here.

3.2.1. Hypothalamic-pituitary system

The hypothalamus is the highest division of the endocrine system. This structure of the brain receives and processes information about changes in motivational systems, changes in the external environment and in the state of internal organs, changes in the humoral constants of the body.

In accordance with the needs of the body, the hypothalamus modulates the activity of the endocrine system by controlling the functions of the pituitary gland (Fig. 3-1).

Modulation (i.e. activation or inhibition) is carried out through the synthesis and secretion of special hormones - releasing hormones ( release- secrete), which, entering a special (portal) circulatory system, are transported to the anterior lobe of the pituitary gland. In the anterior lobe of the pituitary gland, hypothalamic hormones stimulate (or inhibit) the synthesis and secretion of pituitary hormones, which enter the general bloodstream. Some pituitary hormones are tropic ( tropos– direction) hormones, i.e. they stimulate the secretion of hormones from the peripheral glands: the adrenal cortex, gonads (sex glands) and the thyroid gland. There are no pituitary hormones that inhibit the functions of peripheral glands. Another part of the pituitary hormones does not act on peripheral glands, but directly on organs and tissues. For example, prolactin stimulates the mammary gland. Peripheral hormones, interacting with the pituitary gland and hypothalamus, inhibit the secretion of the corresponding hypothalamic and pituitary hormones through a feedback mechanism. This is, in the most general terms, the organization of the central department of the endocrine system.

Rice. 3–1. A – drawing by Leonardo da Vinci. The hypothalamus is located approximately at the point where the planes intersect.

B – Scheme of the structure of the hypothalamic-pituitary region: 1 – hypothalamus, 2 – anterior pituitary gland, 3 – posterior pituitary gland: (a) – neurons synthesizing vasopressin and oxytocin; (b) – neurons secreting releasing hormones; (c) – cell of the anterior pituitary gland, secreting tropic hormones; (d) – portal circulatory system, through which releasing hormones are transmitted from the hypothalamus to the pituitary gland; (e) – systemic blood flow into which pituitary hormones enter.

Oxytocin and vasopressin, synthesized in hypothalamic neurons, enter the processes of nerve cells into synapses that border directly on blood vessels. Thus, these two hormones, synthesized in the hypothalamus, are released into the bloodstream in the pituitary gland. Other hormones, synthesized in the hypothalamus, enter the vessels of the portal circulatory system, which connects the hypothalamus and pituitary gland. In the pituitary gland, they are released and act on pituitary cells, regulating the synthesis and secretion of pituitary hormones, which enter the general bloodstream.

The hypothalamus integrates the processing of information entering the central nervous system. The hypothalamus also synthesizes releasing hormones, which control the pituitary gland. In the pituitary gland, under the influence of hypothalamic hormones, the synthesis of pituitary hormones increases or decreases. Pituitary hormones are distributed through the general bloodstream. Some of them affect body tissues, and some stimulate the synthesis of hormones in peripheral endocrine glands (called tropic hormones).

Some of the hypothalamic neurons, in which releasing hormones are synthesized, send out processes into many parts of the brain. In these neurons, releasing hormone molecules, released at synapses, act as mediators.

By chemical nature, all hypothalamic and pituitary hormones are peptides, that is, they consist of amino acids. Peptides are proteins whose molecules consist of a small number of amino acids - no more than a hundred. For example, the thyrotropin-releasing hormone molecule consists of three amino acids, the corticoliberin molecule consists of 41, and the molecule of a hormone such as prolactin-inhibiting factor (which will not be discussed in this course) consists of only one amino acid. Due to their peptide nature, all hypothalamic and pituitary hormones, entering the blood, are very quickly decomposed by enzymes. The time during which the content of the administered peptide is halved (half-life) is usually several minutes. This makes them difficult to define and determines some features of their action. Additional difficulties in determining the concentration of hypothalamic hormones are created by the fact that in the absence of external stimuli their secretion occurs in separate peaks. Therefore, for most hypothalamic hormones, their concentration in the blood in a state of physiological norm is determined only by indirect methods.

All hypothalamic hormones, in addition to endocrine functions, have a pronounced psychotropic effect. Unlike hypothalamic hormones, not all pituitary hormones have a psychotropic effect. For example, the influence of follicle-stimulating and luteotropic hormones on behavior is due only to their influence on other endocrine glands.

All hypothalamic hormones affect mental functions, i.e. they are psychotropic agents.

3.2.2. Hypothalamic and pituitary hormones

We will consider in detail only some hypothalamic hormones and the corresponding endocrine systems. Corticotropic hormone (CRH), synthesized in the hypothalamus, stimulates the secretion of adrenocorticotropic hormone (ACTH) in the anterior pituitary gland. ACTH stimulates the function of the adrenal cortex. Gonadotropin-releasing hormone (GnRH or LH-RH), synthesized in the hypothalamus, stimulates the secretion of follicle-stimulating (FSH) and luteotropic (LH) hormones in the anterior pituitary gland. FSH and LH stimulate the function of the gonads (sex glands). LH stimulates the production of sex hormones, and FSH stimulates the production of germ cells in the gonads. Thyrotropin-releasing hormone (TRH), synthesized in the hypothalamus, stimulates the secretion thyroid-stimulating hormone(TSH) in the anterior pituitary gland. TSH stimulates the secretory activity of the thyroid gland.

Endorphins and enkephalins are secreted in the hypothalamus (as well as in other structures of the central nervous system) and the pituitary gland. These are groups of peptide hormones (in the pituitary gland) and neuromodulators and mediators (in the hypothalamus), which have two main functions: they reduce pain and improve mood - causing euphoria. Due to the euphoric effect of these hormones, i.e. the ability to elevate mood, they are involved in the development of new forms of behavior, being part of the reinforcement system in the central nervous system. The secretion of endorphins increases under stress.

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Perm State

Technical University

Department of Physical Culture.

Regulation of nervous activity: humoral and nervous.
Features of the functioning of the central nervous system.

Completed by: student of group ASU-01-1
Kiselev Dmitry

Checked: _______________________

_______________________

Perm 2003

The human body is a single self-developing and self-regulating system.

All living things are characterized by four characteristics: growth, metabolism, irritability and the ability to reproduce themselves. The combination of these characteristics is characteristic only of living organisms. Man, like all other living beings, also has these abilities.

Normal healthy man does not notice the internal processes occurring in his body, for example, how his body processes food. This happens because in the body all systems (nervous, cardiovascular, respiratory, digestive, urinary, endocrine, reproductive, skeletal, muscular) interact harmoniously with each other without the person himself directly interfering in this process. We often have no idea how this happens, and how all the most complex processes in our body are controlled, like one vital important function the body combines and interacts with another. How nature or God took care of us, what tools they provided our body with. Let's consider the mechanism of control and regulation in our body.

In a living organism, cells, tissues, organs and organ systems work as a single unit. Their coordinated work is regulated by two fundamentally different, but aimed at the same ways: humorally (from lat. "humor"– liquid: through blood, lymph, intercellular fluid) and nervously. Humoral regulation is carried out with the help of biologically active substances - hormones. Hormones are secreted by endocrine glands. The advantage of humoral regulation is that hormones are delivered through the blood to all organs. Nervous regulation is carried out by organs of the nervous system and acts only on the “target organ”. Nervous and humoral regulation carries out the interconnected and coordinated work of all organ systems, so the body functions as a single whole.

Humoral system

The humoral system for regulating metabolism in the body is a collection of endocrine and mixed secretion glands, as well as ducts that allow biologically active substances (hormones) to reach blood vessels or directly affected organs.

Below is a table showing the main endocrine and mixed glands and the hormones they secrete.

As can be seen from the table below, the endocrine glands influence both normal organs, and on other endocrine glands (this ensures self-regulation of the activity of the endocrine glands). The slightest violations in the activity of this system, they lead to developmental disorders of the entire organ system (for example, with hypofunction of the pancreas, diabetes mellitus develops, and with hyperfunction of the anterior pituitary gland, gigantism may develop).

The lack of certain substances in the body can lead to the inability to produce certain hormones in the body and, as a result, to impaired development. For example, insufficient intake of iodine (J) in the diet can lead to the inability to produce thyroxine (hypothyroidism), which can lead to the development of diseases such as myxedema (dry skin, hair loss, decreased metabolism) and even cretinism (stunted growth, mental development).

Nervous system

The nervous system is the unifying and coordinating system of the body. It includes the brain and spinal cord, nerves, and associated structures such as the meninges (layers of connective tissue around the brain and spinal cord).

Despite the well-defined functional separation, the two systems are largely related.

With the help of the cerebrospinal system (see below), we feel pain, temperature changes (heat and cold), touch, perceive the weight and size of objects, feel the structure and shape, the position of body parts in space, feel vibration, taste, smell, light and sound. In each case, stimulation of the sensory endings of the corresponding nerves causes a stream of impulses that are transmitted by individual nerve fibers from the site of the stimulus to the corresponding part of the brain, where they are interpreted. When any of the sensations is formed, impulses spread across several neurons separated by synapses until they reach conscious centers in the cerebral cortex.

In the central nervous system, the received information is transmitted by neurons; the pathways they form are called tracts. All sensations, except visual and auditory, are interpreted in the opposite half of the brain. For example, the touch of the right hand is projected to the left hemisphere of the brain. Sound sensations coming from each side enter both hemispheres. Visually perceived objects are also projected into both halves of the brain.

The figures on the left show the anatomical location of the nervous system organs. The figure shows that the central part of the nervous system (brain and spinal cord) is concentrated in the head and in spinal canal, while the organs of the peripheral nervous system (nerves and ganglia) are distributed throughout the body. This structure of the nervous system is the most optimal and has been developed evolutionarily.

Conclusion

The nervous and humoral systems have the same goal - to help the body develop and survive in changing environmental conditions, so it makes no sense to talk separately about nervous or humoral regulation. There is a single neurohumoral regulation, which uses "humoral" and " nervous mechanisms"for regulation. "Humoral mechanisms" set the general direction in the development of the body's organs, and "nervous mechanisms" make it possible to correct the development of a specific organ. It is a mistake to assume that the nervous system is given to us only to think; it is a powerful tool that is also unconscious regulates such vital biological processes as food processing, biological rhythms and much more. Amazingly, even the smartest and most active person uses only 4% of their brain capacity. The human brain is a unique mystery that has been fought over from ancient times to the present day and, perhaps, will be fought for more than one thousand years.

Bibliography:

1. "General Biology" edited by; ed. "Enlightenment" 1975

3. Encyclopedia "Around the World"

4. Personal notes on biology grades 9-11

A variety of life-support processes are constantly taking place in the human body. So, during the period of wakefulness, all organ systems function simultaneously: a person moves, breathes, blood flows through his vessels, digestion processes take place in the stomach and intestines, thermoregulation is carried out, etc. A person perceives all changes occurring in the environment, reacts to them. All these processes are regulated and controlled by the nervous system and glands of the endocrine apparatus.

Humoral regulation (from the Latin “humor” - liquid) is a form of regulation of the body’s activity, inherent in all living things, carried out with the help of biologically active substances - hormones (from the Greek “hormao” - I excite), which are produced by special glands. They are called endocrine or endocrine glands (from the Greek “endon” - inside, “crineo” - to secrete). The hormones they secrete enter directly into the tissue fluid and blood. The blood carries these substances throughout the body. Once in organs and tissues, hormones have a certain effect on them, for example, they affect tissue growth, the rhythm of contraction of the heart muscle, cause a narrowing of the lumen of blood vessels, etc.

Hormones affect strictly specific cells, tissues or organs. They are very active and act even in negligible quantities. However, hormones are quickly destroyed, so they must be released into the blood or tissue fluid as needed.

Typically, endocrine glands are small: from fractions of a gram to several grams.

The most important endocrine gland is the pituitary gland, located under the base of the brain in a special recess of the skull - the sella turcica and connected to the brain by a thin stalk. The pituitary gland is divided into three lobes: anterior, middle and posterior. Hormones are produced in the anterior and middle lobes, which, entering the blood, reach other endocrine glands and control their work. Two hormones produced in neurons enter the posterior pituitary along the stalk diencephalon. One of these hormones regulates the volume of urine produced, and the second enhances the contraction of smooth muscles and plays a very important role in the process of childbirth.

The thyroid gland is located in the neck in front of the larynx. It produces a number of hormones that are involved in the regulation of growth processes and tissue development. They increase the metabolic rate and the level of oxygen consumption by organs and tissues.

The parathyroid glands are located on the posterior surface of the thyroid gland. There are four of these glands, they are very small, their total mass is only 0.1-0.13 g. The hormone of these glands regulates the content of calcium and phosphorus salts in the blood; with a lack of this hormone, the growth of bones and teeth is impaired, and the excitability of the nervous system increases.

The paired adrenal glands are located, as their name suggests, above the kidneys. They secrete several hormones that regulate the metabolism of carbohydrates and fats, affect the content of sodium and potassium in the body, and regulate the activity of the cardiovascular system.

The release of adrenal hormones is especially important in cases where the body is forced to work under conditions of mental and physical tension, i.e., under stress: these hormones enhance muscle function, increase blood glucose levels (to ensure increased energy expenditure by the brain), increase blood flow in the brain and other vital organs, and increase the level of systemic blood pressure, increase cardiac activity.

Some glands of our body perform a double function, that is, they act simultaneously as glands of internal and external - mixed - secretion. These are, for example, the gonads and the pancreas. The pancreas secretes digestive juice, entering the duodenum; At the same time, its individual cells function as endocrine glands, producing the hormone insulin, which regulates the metabolism of carbohydrates in the body. During digestion, carbohydrates are broken down into glucose, which is absorbed from the intestines into the blood vessels. Decreased insulin production means that most of the glucose cannot penetrate from the blood vessels further into the organ tissues. As a result, cells of various tissues are left without the most important source of energy - glucose, which is ultimately excreted from the body in the urine. This disease is called diabetes. What happens when the pancreas produces too much insulin? Glucose is very quickly consumed by various tissues, primarily muscles, and blood sugar levels drop to dangerously low levels. As a result, the brain lacks “fuel”, the person falls into the so-called insulin shock and loses consciousness. In this case, it is necessary to quickly introduce glucose into the blood.

The sex glands form sex cells and produce hormones that regulate the growth and maturation of the body, the formation of secondary sexual characteristics. In men, this is the growth of mustaches and beards, coarsening of the voice, a change in physique, in women - a high voice, roundness of body shapes. Sex hormones determine the development of the genital organs, the maturation of germ cells, in women they control the phases of the sexual cycle, the course of pregnancy.

Structure of the thyroid gland

The thyroid gland is one of the the most important organs internal secretion. The description of the thyroid gland was given back in 1543 by A. Vesalius, and it received its name more than a century later - in 1656.

Modern scientific ideas about the thyroid gland began to take shape by the end of the 19th century, when the Swiss surgeon T. Kocher in 1883 described signs of mental retardation (cretinism) in a child that developed after the removal of this organ.

In 1896 A. Bauman established high content iodine in the gland and drew the attention of researchers to the fact that even the ancient Chinese successfully treated cretinism with the ashes of sea sponges containing a large amount of iodine. The thyroid gland was first subjected to experimental study in 1927. Nine years later, the concept of its intrasecretory function was formulated.

It is now known that the thyroid gland consists of two lobes connected by a narrow isthmus. It is the largest endocrine gland. In an adult, its mass is 25-60 g; it is located in front and on the sides of the larynx. The gland tissue consists mainly of many cells - thyrocytes, united into follicles (vesicles). The cavity of each such vesicle is filled with the product of thyrocyte activity - colloid. Blood vessels are adjacent to the outside of the follicles, from where the starting materials for the synthesis of hormones enter the cells. It is the colloid that allows the body to do without iodine for some time, which usually comes with water, food, and inhaled air. However, with long-term iodine deficiency, hormone production is impaired.

The main hormonal product of the thyroid gland is thyroxine. Another hormone, triiodothyranium, is produced only in small quantities by the thyroid gland. It is formed mainly from thyroxine after the elimination of one iodine atom from it. This process occurs in many tissues (especially in the liver) and plays an important role in maintaining the hormonal balance of the body, since triiodothyronine is much more active than thyroxine.

Diseases associated with dysfunction of the thyroid gland can occur not only due to changes in the gland itself, but also due to a lack of iodine in the body, as well as diseases of the anterior pituitary gland, etc.

With a decrease in the functions (hypofunction) of the thyroid gland in childhood, cretinism develops, characterized by inhibition in the development of all body systems, short stature, and dementia. In an adult, with a lack of thyroid hormones, myxedema occurs, which causes swelling, dementia, decreased immunity, and weakness. This disease responds well to treatment with thyroid hormone medications. With increased production of thyroid hormones, Graves' disease occurs, in which excitability, metabolic rate, heart rate increase sharply, bulging eyes (exophthalmos) develop and weight loss occurs. In those geographical areas where the water contains little iodine (usually found in the mountains), the population often experiences goiter - a disease in which the secreting tissue of the thyroid gland grows, but cannot synthesize full-fledged hormones in the absence of the required amount of iodine. In such areas, the consumption of iodine by the population should be increased, which can be ensured, for example, by the use of table salt with mandatory small additions of sodium iodide.

A growth hormone

The first suggestion about the secretion of a specific growth hormone by the pituitary gland was made in 1921 by a group of American scientists. In the experiment, they were able to stimulate the growth of rats to twice their normal size by daily administration of pituitary gland extract. In its pure form, growth hormone was isolated only in the 1970s, first from the pituitary gland of a bull, and then from horses and humans. This hormone affects not just one gland, but the entire body.

Human height is not a constant value: it increases until 18-23 years old, remains unchanged until about 50 years old, and then decreases by 1-2 cm every 10 years.

In addition, growth rates vary among individuals. For a “conventional person” (this term is accepted World Organization health care in determining various parameters of life) the average height is 160 cm for women and 170 cm for men. But a person below 140 cm or above 195 cm is considered very short or very tall.

With a lack of growth hormone, children develop pituitary dwarfism, and with an excess, pituitary gigantism. The tallest pituitary giant whose height was accurately measured was the American R. Wadlow (272 cm).

If an excess of this hormone is observed in an adult, when normal height already stopped, acromegaly disease occurs, in which the nose, lips, fingers and toes and some other parts of the body grow.

Test your knowledge

1. What is the essence of humoral regulation of processes occurring in the body?
2. Which glands are classified as endocrine glands?
3. What are the functions of the adrenal glands?
4. Name the main properties of hormones.
5. What is the function of the thyroid gland?
6. What mixed secretion glands do you know?
7. Where do the hormones secreted by the endocrine glands go?
8. What is the function of the pancreas?
9. List the functions of the parathyroid glands.

Think

What can a lack of hormones secreted by the body lead to?

The endocrine glands secrete hormones directly into the blood - biolo! ically active substances. Hormones regulate metabolism, growth, development of the body and the functioning of its organs.