Puberty. Neurohumoral regulation of female sexual functions

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. It is known that if the gonad of the embryo does not develop or is removed, then the female genital organs are formed - the oviducts and the uterus. In order for male reproductive organs to develop, hormonal stimulation from the testes is necessary. The fetal ovary is not a source of hormonal influence on the development of the genital organs. 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 male-type hypothalamus 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 the human reproductive system 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.

In newborn girls, sometimes there is a reaction from the uterus, bleeding similar to menstrual discharge appears, and there is also activity of the mammary glands, including 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, a slight and gradual increase in the secretion of pituitary and gonadal hormones 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. This hormone is very similar to the gonadotropic hormone in the structure of the molecule, and therefore easily and firmly connects with the receptors of those cells that are tuned to be sensitive to gonadotropins. However, the gonadotropin-inhibiting factor does not have any stimulating effect on the gonads. On the contrary, it blocks access to gonadotropin hormone receptors. Such competitive regulation is a typical technique used in the metabolic processes of all living organisms.

The leading role in endocrine regulation at this stage belongs to thyroid hormones and growth hormone. 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 increases, and the gonads begin to produce sex steroid hormones in large quantities. 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. A high concentration of 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. Boys retain high levels of 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. At this stage, the formation of secondary sexual characteristics is completed. In boys, this is the formation of the “Adam’s apple”, facial hair, male-type pubic hair, and completion of the development of axillary hair. Facial hair usually appears in the following order: upper lip, chin, cheeks, neck. This trait develops later than others and is finally formed by age 20 or later. Spermatogenesis reaches its full development, the young man’s body is ready for fertilization. Body growth practically stops at this stage.

Girls experience menarche at this stage. Actually, the first menstruation is the beginning of the last, fifth, stage of puberty for girls. Then, over the course of several months, the formation of a characteristic rhythm for women of ovulation and menstruation occurs. Menstruation for most women lasts from 3 to 7 days and repeats every 24-28 days. The cycle is considered established when menstruation occurs at the same intervals, lasts the same number of days with the same intensity distribution over the days. At first, menstruation may last 7-8 days, disappear for several months, even for a year. The appearance of regular menstruation indicates the achievement of puberty: the ovaries produce mature eggs ready for fertilization. Body length growth stops at this stage in 90% of girls.

The described dynamics of puberty clearly demonstrates that in girls this process occurs spasmodically and is less extended over time than in boys.

Features of adolescence. During puberty, not only the function of the hypothalamic-pituitary system and the activity of the gonads are radically restructured, all physiological functions without exception undergo significant, sometimes revolutionary changes. This often leads to the development of an imbalance of individual systems among themselves, a violation of consistency in their action, which negatively affects the functional state of the body. In addition, the influence of hormones extends to the functions of the central nervous system, as a result of which adolescents experience a serious crisis associated with internal and external factors. The emotional sphere of adolescents and numerous self-regulation mechanisms are especially unstable during this period.

All this should be taken into account by teachers and parents, who often forget about the features of the “transitional” age, especially about the physiological stress that children experience during this period. Meanwhile, many psychological characteristics of adolescents are due to their poor health, frequent and sudden changes in the hormonal situation in the body, the emergence of completely new and not always pleasant bodily sensations, to which gradual adaptation is required.

For example, for many girls, the first menstruation is often accompanied by quite severe pain, weakness, a general loss of tone, and significant blood loss. Sometimes the body temperature rises, disturbances in the functioning of the digestive system occur, and vegetative disorders are observed (dizziness, nausea, vomiting, etc.). All this, naturally, leads to irritability and uncertainty; moreover, girls are often embarrassed by the changes happening to them and do not know how to explain their condition. The teacher and parents need to show special tact and respect for the child at such a moment. It would be a mistake to force a girl to limit her movements during “critical days” and abandon her usual regime - on the contrary, maintaining the usual mode of behavior (if her state of health allows) helps to quickly overcome unpleasant sensations and the age crisis in general. However, it is necessary to take a reasonable approach to the level and nature of physical activity that is permissible during such periods: of course, any power loads associated with straining, as well as excessive loads - long walking, cycling, skiing, etc. should be excluded. transitions, hypothermia and overheating should be avoided. For hygienic reasons, it is better not to take a bath during this period, but to use a shower. During the cold season, young people should not sit on metal and stone surfaces, because hypothermia of the organs located in the pelvis and lower abdominal cavity is fraught with the development of a number of serious diseases. Any painful sensation in a teenager is a reason to consult a doctor: it is much easier to prevent a disease than to treat it afterward.

Boys have no problems with regular bleeding. However, the changes in their body during puberty are also very significant and are sometimes a cause for surprise and concern for both the child himself and the adults around him, who have often already forgotten how this period proceeded for them. In addition, in the modern world there are many single-parent families where boys are raised by mothers and grandmothers who are simply unaware of the specific “male” troubles of puberty. The first thing that often worries boys at the third or fourth stage of puberty is gynecomastia, i.e. swelling and tenderness of the mammary glands. In this case, sometimes a clear liquid is released from the nipple, similar in composition to colostrum. As mentioned above, this period does not last long and the unpleasant sensations end on their own after a few months, however, it is important to follow hygiene rules: keep the breasts clean, do not introduce an infection into it with your hands, which can complicate the natural process for a long time. Following this stage, there is a rapid increase in the size of the penis, which creates unpleasant sensations at first, especially if the boy wears tight-fitting clothes - shorts and jeans. Touching the head of the penis with clothing during this period can be unbearably painful, since the powerful receptive field of this area of the skin has not yet been adapted to mechanical influences. Although all boys are familiar with erections right from birth (the penis becomes erect in healthy children during urination), the organ, which has greatly increased in size at the time of erection, causes physical suffering to many adolescents, not to mention psychological stress. Meanwhile, a normally healthy teenager, like a young adult man, wakes up almost every day with a strongly erect penis - this is a natural consequence of the activation of the vagus nerve during sleep. Teenagers are often embarrassed by this condition, and the demands of parents (or teachers in child care institutions) to immediately leave bed after waking up are impossible for them precisely for this reason. The child should not be pressured in this regard: over time, he will develop the correct behavior that will allow him to psychologically adapt to this physiological feature. 2-3 minutes after waking up, the erection goes away on its own, and the teenager can get out of bed without feeling awkward. Similar situations occur when sitting for a long time, especially on a soft surface: blood rushes to the pelvic organs, and a spontaneous erection occurs. This often happens when riding on public transport. Such an erection has nothing to do with sexual arousal and goes away quickly and painlessly in 1-2 minutes. The main thing is not to concentrate the teenager’s attention on this fact, and certainly not to shame him - it is not his fault at all that he is healthy.

At the fourth or fifth stage of puberty (usually at 15-16 years old), the young man is almost ready for fertilization, his testes continuously produce mature sperm, and seminal fluid accumulates in the epididymis - a special connective tissue vessel, where it is stored until ejaculation (ejaculation). ). Since this process occurs continuously, the amount of seminal fluid increases, and sometimes the limited volume of the epididymis is not able to accommodate new portions of the seed. In this case, the body is able to spontaneously free itself from the accumulated product - this phenomenon is called a wet dream and usually happens at night. Wet dreams are a normal, healthy and biologically appropriate reaction of a young body. The ejected seed frees up space for new portions of the production of the sex glands, and also prevents poisoning of the body by the decay products of its own seed. In addition, sexual tension, which is not realized by the young man, affecting the activity of all spheres of nervous and hormonal control, is discharged thanks to wet dreams, and the state of the body is normalized.

Sexual desire, which awakens in girls and boys in the final stages of the pubertal process, without having an outlet, often develops into a serious problem. Many of them find various ways to relieve themselves, including through masturbation. In earlier times, the attitude towards masturbation was sharply negative; doctors assured that it could lead to impotence and mental changes. However, studies conducted in the second half of the 20th century did not confirm the existence of such cause-and-effect relationships; on the contrary, it is now generally accepted that masturbation is a normal and acceptable means of relieving excess tension when there is no other way to satisfy sexual desire. Teenagers should not be encouraged, but in no case should they be reproached or punished for masturbation - this will go away on its own without any consequences after they become adults and begin to have a regular sex life. However, it is very important in all cases of manipulation of the external genitalia to strictly observe hygiene and infection prevention measures. Regular hand washing and daily hygiene of the external genitalia are the most important habits that boys and girls should learn.

Zero stage – newborn stage - 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 considered as a stage of sexual infantilism. During this period, the regulatory structures of the brain mature and there is a gradual and slight increase in the secretion of pituitary hormones. The development of the gonads is not observed 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. This hormone is very similar in molecular structure to gonadotropin hormone, and therefore easily and firmly connects with the receptors of those cells that are tuned to be sensitive to gonadotropins. However, the gonadotropin-inhibiting factor does not have any stimulating effect on the gonads. On the contrary, it blocks the gonadotropin hormone from accessing the receptors. Such competitive regulation is typical of hormonal regulation of metabolism. The leading role in endocrine regulation at this stage belongs to thyroid hormones and growth hormone. Just before puberty, the secretion of growth hormone increases, and this causes an acceleration of growth processes. The external and internal genitalia develop inconspicuously, and there are no secondary sexual characteristics. The stage ends for girls at 8–10 years, and for boys at 10–13 years. The long duration of the stage leads to the fact that upon entering puberty, boys are larger than girls.

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. The sensitivity of the gonads to pituitary influences increases, and effective feedback is gradually established in the hypothalamus-pituitary-gonadal system. In girls during this 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, sometimes it occurs asymmetrically. 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 11–13 years for boys, and at 9–11 years 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 sex steroid hormones in large quantities. 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, approaching the size of an adult by the age of 15. A high concentration of 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 disappear without intervention several months after their appearance. At this stage, both boys and girls experience intense hair growth in the pubis and armpits. The stage ends for girls at 11–13, and for boys at 12–16 years.

Fourth stage - stage of maximum steroidogenesis. The activity of the gonads reaches a maximum, the adrenal glands synthesize a large amount of sex steroids. Boys retain high levels of 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 – the stage of final formation – is physiologically characterized by the establishment of a balanced feedback between pituitary hormones and peripheral glands and begins in girls at 11–13 years old, in boys – at 15–17 years old. At this stage, the formation of secondary sexual characteristics is completed. In boys, this is the formation of the “Adam's apple”, facial hair, male-type pubic hair, and completion of the development of axillary hair. Facial hair usually appears in the following order: upper lip, chin, cheeks, neck. This trait develops later than others and is finally formed by age 20 or later. Spermatogenesis reaches its full development, the young man’s body is ready for fertilization. Body growth practically stops.

Girls experience menarche at this stage. Actually, the first menstruation is the beginning of the last, fifth, stage of puberty for girls. Then, over the course of several months, the formation of a characteristic rhythm for women of ovulation and menstruation occurs. The cycle is considered established when menstruation occurs at the same intervals, lasts the same number of days with the same intensity distribution over the days. At first, menstruation may last 7–8 days, disappear for several months, even for a year. The appearance of regular menstruation indicates the achievement of puberty: the ovaries produce mature eggs ready for fertilization. Body growth in length also practically stops.

During the second to fourth stages of puberty, a sharp increase in the activity of the endocrine glands, intensive growth, structural and physiological changes in the body increase the excitability of the central nervous system. This is expressed in the emotional response of adolescents: their emotions are mobile, changeable, contradictory: increased sensitivity is combined with callousness, shyness with swagger; excessive criticism and intolerance towards parental care appear. During this period, a decrease in performance and neurotic reactions - irritability, tearfulness (especially in girls during menstruation) are sometimes observed. New relationships between the sexes are emerging. Girls become more interested in their appearance, boys demonstrate their strength. The first love experiences often unsettle teenagers, they become withdrawn and begin to study worse.

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 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.

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.

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.

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 increases, and the gonads begin to produce sex steroid hormones in large quantities. 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. A high concentration of 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. Boys retain high levels of growth hormone, so they continue to grow rapidly; in girls, growth processes slow down.

PC is a complex neurohumor reflex. percent, accompanying the complex physiol and morph changes in the sex organs and all organs of the female from one stage of exciter to another. During this period, a number of changes occurred: 3 stages – 1. excitation 2. inhibition 3. balancing
---St. exc:
There were 4 phenomena - estrus, general reaction to excitatory sex, heat, follicle maturity and ovulation. In a herd of food, all reflexes, even food, are subordinated to the sexual. Increase the cr. pressure, the composition of the blood and the quality of milk change. In the sex org, the growth of vasitxyjuj cells and the mucous layer and nerve formations, in the endo and myometrium, increased blood flow, increased oxidation, increased absorption of oxygen by the uterine mucosa, activation of catalase and peroxidase. In the reproductive and other systems of the body, proliferative percentages predominate.
Estrus - the percentage of mucus secretion from the sex org of the female as a consequence of the morphologist of changes in sex appt. Diagnose by examining the bed. floor. org. Hyperemia of the floor of the apparatus, growth of silizus, rejection of epithelial cells, dilation of the cervix, some are alive, rupture of small vessels and bleeding. According to the degree of dilatation of the cervix, estrus of the 1st, 2nd, 3rd degree is distinguished.
The sex of the female is a change in the behavior of the female, which arose in connection with the maturity of the fall. Occurs later than estrus, anxiety, refusal of food, decreased productivity, change. pumping milk, viciousness. The female has shown interest in the male, she can jump on him, but does not allow the cage. As the concentration of estrogen in the blood increases, estrus and sexual excitability intensify; the effect of these hormones on the nervous system causes sexual desire.
Hunting - put sex. The female’s reaction to the male, showing a sex reflex, strives to get closer to the male, takes a pose for urination, often performing the act of urination, which, having completed the rhythmic contraction of the sex of the lips, allows mounting and coitus.
Maturation of the foll and ovule - nga division of the ovary 2 zones - cortical (follicle, from the stem, rich in spindle fibrocytes, few fibers, contains foll and corpus luteum) and medulla - vascular. Prouc vsuryt ripe fall - ovulation.
--Step braking - the stud weakened the recognition of the floor ex. Start immediately after 1st abc. The hunt is replaced by a brightly expressed retreat, an indifferent attitude towards the male in place of the ovular fall, having developed a yellow body. By reducing the hyperemia and volume of all glands of the sex appendix, the cervix closes, no mucus is secreted, the glands of the sex appendix undergo reverse development, and the layers that have grown into the epithelial vagina are rejected. Nuclear cells and scales with a large number of leukocytes were found in the moisture. The predominance of the phenomenon of involution of all processes, disturbances in the herd of excitement. Calm alive, the appetite has been restored, the quality of milk has improved, the blood has changed, the structure of the mucous membranes has improved. The female is aggressive towards the male.
--Standard balance - us after braking, lasts until the onset of a new stage of excitation. The female is indifferent to the male; the eggs contain a follicle and functioning corpus luteum for half the cycle.
Proliferative and degenerative percentages are equally expressed. The cervix is closed. A microscope of a moisture smear revealed predominantly mucus, leukocytes, squamous nuclear epithelial cells and scales.
The rhythm of sexual cycles, the sequence and interrelation of sexual phenomena (ovulation, estrus, heat and sexual arousal) can be explained by the interaction of the nervous and humoral systems of the body. A necessary condition for the occurrence and course of sexual cycles is the presence of two groups of hormones: gonadotropic and gonadal (ovarian). There are three gonadotropic hormones produced by the pituitary gland: follicle-stimulating hormone (FSH), luteinizing hormone (LH) and luteotropic hormone (LTG), or lactogenic. FSH causes the growth and maturation of follicles in the ovaries. Under the influence of luteinizing hormone (with an optimal ratio of FSH and LH, approximately 1:10), ovulation and the formation of the corpus luteum occur. If this physiological ratio is violated, then ovulation does not occur (anovulatory sexual cycle). The corpus luteum is formed under the influence of LH, and LTG regulates its function and stimulates the formation of milk during lactation.
Gonadal hormones involved in the regulation of the reproductive cycle are produced in the ovaries. These include follicular hormone (folliculin, folliculosterone) and corpus luteum hormone (progesterone, luteohormone). The follicular hormone produced in maturing follicles is called estrogen, as it causes estrus in animals. There are three types of estrogens: estrone, estradiol and estriol. The most active follicular hormone is estradiol, and estrone and estriol are products of its transformations; Estrogens are also produced in significant quantities by the placenta and in smaller quantities by the adrenal cortex and testes.
The highest hormonal activity of the corpus luteum of the reproductive cycle appears on the 10-12th day, when it reaches its maximum development.
Progesterone determines the development of the secretory function of the endometrium, prepares the uterine mucosa for the attachment of the embryo and its normal development. This is an extremely important function of progesterone. If it is deficient, the embryo dies. Progesterone helps maintain pregnancy in the early stages; Squeezing out the corpus luteum of the ovary during this period causes abortion. This hormone inhibits the growth of follicles and ovulation, prevents contraction of the uterus, maintaining it in a state of balance. In addition, the hormone of the corpus luteum causes hypertrophy of the mammary glands and prepares them for lactation.
The entire specified humoral system
receives primary impulses from the cerebral cortex.
It has been experimentally established that the introduction of FSH into the body of a castrated female does not cause morphological changes in her reproductive system. Consequently, FSH acts on the reproductive system only through the ovaries. In uncastrated females, FSH provokes the development of the follicle, accompanied by the production of the female sex hormone in it - folliculin,
determining the estrus pattern. The administration of folliculin to immature or sexually mature females does not affect the ovaries, but is accompanied by an enlargement of the uterus, swelling of its mucous membrane, increased secretion of all glands of the reproductive apparatus and other signs of estrus. The same picture is given by folliculin in castrated animals. Thus, follicular hormone acts only on the conductive tract of the reproductive apparatus, causing its hyperemia, secretion and proliferation. It stimulates the contraction of the muscles of the uterus and its horns, increasing their sensitivity to the action of pituitrin. The accumulation of folliculin in the body causes a reaction in the nervous system, manifested by sexual arousal and hunting. The concentration of the hormone changes throughout the sexual cycle.
In addition to internal factors, the formation and manifestation of the sexual cycle is also influenced by external factors. Of the external factors affecting the reproductive cycle, food, light and the male as a specific stimulator of the reproductive system are of primary importance.
The food supplies sterones and vitamins, from which folliculin-like substances are synthesized in the body. They can also form in body tissues under the influence of sunlight (insolation).
Irritation from the sun's rays of the receptors of the eyes and skin, sterones of the digestive tract and other organs, as well as olfactory, visual, auditory and tactile perceptions, which arise especially intensely in the presence of a male, are transmitted through the centripetal nerves to the perceptive centers of the cerebral cortex. From the cortex analyzers, impulses travel along centrifugal pathways to the hypothalamus. Here, in particular in its supraoptic and paraventricular nuclei, a neurosecretion (releasing factor) is formed, which through the blood (portal vein) affects the pituitary gland, prompting the latter to release FSH. The entry of follicle-stimulating hormone into the blood determines the development and maturation of the follicle. The maturation of the follicle is accompanied by the formation of estrogens, which, through chemoreceptors and brain analyzers, cause estrus, general arousal and hunting. The presence of a large amount of estrogens inhibits the secretion of FSH and at the same time stimulates the release of LH, which causes ovulation and the formation of the corpus luteum. The corpus luteum hormone inhibits further release of LH and stimulates the luteotropic function of the pituitary gland without interfering with the secretion of FSH, resulting in the growth of new follicles and the sexual cycle repeats. For normal. During the course of sexual cycles, hormones from the pineal gland (through which light effects are realized), adrenal glands, thyroid and other glands are necessary.
When pregnancy occurs, the proliferative processes in the uterus that arose during estrus are intensified under the influence of the corpus luteum hormone.
The influence of all hormones of the reproductive cycle and their very formation in the body occur as a consequence of the stimulating effect of the nervous system. When the pituitary gland is denervated (disruption of nerve connections), its functions are disrupted and sexual cycles stop.

The mechanisms of regulation of physiological functions are traditionally divided into nervous and humoral, although in reality they form a single regulatory system that ensures the maintenance of homeostasis and adaptive activity of the body. These mechanisms have numerous connections both at the level of functioning of nerve centers and in the transmission of signal information to effector structures. Suffice it to say that when the simplest reflex is implemented as an elementary mechanism of nervous regulation, the transmission of signaling from one cell to another is carried out through humoral factors - neurotransmitters. The sensitivity of sensory receptors to the action of stimuli and the functional state of neurons changes under the influence of hormones, neurotransmitters, a number of other biologically active substances, as well as the simplest metabolites and mineral ions (K+, Na+, Ca-+, C1~). In turn, the nervous system can initiate or correct humoral regulations. Humoral regulation in the body is under the control of the nervous system.

Humoral mechanisms are phylogenetically more ancient; they are present even in unicellular animals and acquire great diversity in multicellular animals and especially in humans.

Nervous regulatory mechanisms were formed phylogenetically and are formed gradually during human ontogenesis. Such regulations are possible only in multicellular structures that have nerve cells that are united into nerve chains and make up reflex arcs.

Humoral regulation is carried out by the distribution of signaling molecules in body fluids according to the principle of “everyone, everyone, everyone”, or the principle of “radio communication”.

Nervous regulation is carried out according to the principle of “letter with an address”, or “telegraph communication”. Signaling is transmitted from nerve centers to strictly defined structures, for example, to precisely defined muscle fibers or their groups in a specific muscle. Only in this case are targeted, coordinated human movements possible.

Humoral regulation, as a rule, occurs more slowly than nervous regulation. The speed of signal transmission (action potential) in fast nerve fibers reaches 120 m/s, while the speed of transport of a signal molecule with the blood flow in arteries is approximately 200 times less, and in capillaries it is thousands of times less.

The arrival of a nerve impulse to the effector organ almost instantly causes a physiological effect (for example, contraction of skeletal muscle). The response to many hormonal signals is slower. For example, the manifestation of a response to the action of hormones of the thyroid gland and adrenal cortex occurs after tens of minutes and even hours.

Humoral mechanisms are of primary importance in the regulation of metabolic processes, the rate of cell division, growth and specialization of tissues, puberty, and adaptation to changing environmental conditions.

The nervous system in a healthy body influences all humoral regulations and corrects them. At the same time, the nervous system has its own specific functions. It regulates life processes that require quick reactions, ensures the perception of signals coming from sensory receptors of the senses, skin and internal organs. Regulates the tone and contractions of skeletal muscles, which ensure the maintenance of posture and movement of the body in space. The nervous system ensures the manifestation of such mental functions as sensation, emotions, motivation, memory, thinking, consciousness, and regulates behavioral reactions aimed at achieving a useful adaptive result.

Humoral regulation is divided into endocrine and local. Endocrine regulation is carried out due to the functioning of the endocrine glands (endocrine glands), which are specialized organs that secrete hormones.

A distinctive feature of local humoral regulation is that biologically active substances produced by the cell do not enter the bloodstream, but act on the cell producing them and its immediate environment, spreading through diffusion through the intercellular fluid. Such regulations are divided into regulation of metabolism in the cell due to metabolites, autocrin, paracrin, juxtacrin, and interactions through intercellular contacts. In all humoral regulations carried out with the participation of specific signaling molecules, cellular and intracellular membranes play an important role.

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(From the Latin word humor - “liquid”) is carried out due to substances released into the internal environment of the body (lymph, blood, tissue fluid). This is a more ancient regulation system compared to the nervous system.

Examples of humoral regulation:

adrenaline (hormone)
histamine (tissue hormone)
carbon dioxide in high concentration (formed during active physical work)

causes local expansion of capillaries, more blood flows to this place
stimulates the respiratory center of the medulla oblongata, breathing intensifies

Comparison of nervous and humoral regulation

By speed of work: nervous regulation is much faster: substances move along with the blood (the effect occurs after 30 seconds), nerve impulses occur almost instantly (tenths of a second).
By duration of work: humoral regulation can act much longer (while the substance is in the blood), the nerve impulse acts for a short time.
By scale of impact: humoral regulation operates on a larger scale, because
Humoral regulation

chemicals are carried by the blood throughout the body, nervous regulation acts precisely - on one organ or part of an organ.

Thus, it is advantageous to use nervous regulation for fast and precise regulation, and humoral regulation for long-term and large-scale regulation.

Relationship nervous and humoral regulation: chemicals affect all organs, including the nervous system; nerves go to all organs, including the endocrine glands.

Coordination Nervous and humoral regulation is carried out by the hypothalamic-pituitary system, thus we can talk about a unified neurohumoral regulation of body functions.

Main part. The hypothalamic-pituitary system is the highest center of neurohumoral regulation

Introduction.

The hypothalamic-pituitary system is the highest center of neurohumoral regulation of the body. In particular, hypothalamic neurons have unique properties - to secrete hormones in response to PD and generate PD (similar to PD when excitation arises and spreads) in response to hormone secretion, that is, they have the properties of both secretory and nerve cells at the same time. This determines the connection between the nervous system and the endocrine system.

From the course of morphology and practical lessons in physiology, we are well aware of the location of the pituitary gland and hypothalamus, as well as their close connection with each other. Therefore, we will not dwell on the anatomical organization of this structure, and will move directly to the functional organization.

Main part

The main endocrine gland is the pituitary gland - the gland of glands, the conductor of humoral regulation in the body. The pituitary gland is divided into 3 anatomical and functional parts:

1. The anterior lobe or adenohypophysis - consists mainly of secretory cells that secrete tropic hormones. The work of these cells is regulated by the work of the hypothalamus.

2. Posterior lobe or neurohypophysis - consists of axons of nerve cells of the hypothalamus and blood vessels.

3. These lobes are separated by the intermediate lobe of the pituitary gland, which in humans is reduced, but nevertheless is capable of producing the hormone intermedin (melanocyte-stimulating hormone). This hormone is secreted in humans in response to intense light irritation of the retina and activates the cells of the black pigment layer in the eye, protecting the retina from damage.

The functioning of the entire pituitary gland is regulated by the hypothalamus. The adenohypophysis is subject to the work of tropic hormones secreted by the pituitary gland - releasing factors and inhibitory factors according to one nomenclature, or liberins and statins according to another. Liberins or releasing factors stimulate, and statins or inhibitory factors inhibit the production of the corresponding hormone in the adenohypophysis. These hormones enter the anterior pituitary gland through the portal vessels. In the hypothalamic region, a neural network is formed around these capillaries, formed by processes of nerve cells that form neuro-capillary synapses on the capillaries. The outflow of blood from these vessels goes straight to the adenohypophysis, carrying with it hypothalamic hormones. The neurohypophysis has a direct neural connection with the nuclei of the hypothalamus, along the axons of the nerve cells of which hormones are transported to the posterior lobe of the pituitary gland. There they are stored in extended axon terminals, and from there they enter the blood when PD is generated by the corresponding neurons of the hypothalamus.

Regarding the regulation of the posterior lobe of the pituitary gland, it should be said that the hormones secreted by it are produced in the supraoptic and paraventricular nuclei of the hypothalamus, and are transported to the neurohypophysis by axonal transport in transport granules.

It is also important to note that the dependence of the pituitary gland on the hypothalamus is proven by transplanting the pituitary gland to the neck. In this case, it stops secreting tropic hormones.

Now let's discuss the hormones secreted by the pituitary gland.

Neurohypophysis produces only 2 hormones oxytocin and ADH (antidiuretic hormone) or vasopressin (preferably ADH, because this name better reflects the action of the hormone). Both hormones are synthesized in both the supraoptic and paraventricular nuclei, but each neuron synthesizes only one hormone.

ADH– target organ – kidneys (in very high concentrations it affects blood vessels, increasing blood pressure, and in the portal system of the liver reducing it; important for large blood loss), with the secretion of ADH, the collecting ducts of the kidneys become permeable to water, which increases reabsorption, and with absence - reabsorption is minimal and practically absent. Alcohol reduces the production of ADH, which is why diuresis increases, water loss occurs, hence the so-called hangover syndrome (or in common parlance - dryness). We can also say that under conditions of hyperosmolarity (when the salt concentration in the blood is high), the production of ADH is stimulated, which ensures minimal water loss (concentrated urine is formed). Conversely, under conditions of hypoosmolarity, ADH increases diuresis (diluted urine is produced). Consequently, we can say about the presence of osmo- and baroreceptors that control osmotic pressure and blood pressure (arterial pressure). Osmoreceptors are probably located in the hypothalamus itself, the neurohypophysis and the portal vessels of the liver. Baroreceptors are located in the carotid artery and aortic bulb, as well as in the thoracic region and atrium, where pressure is minimal. Regulate blood pressure in horizontal and vertical positions.

Pathology. If the secretion of ADH is impaired, diabetes insipidus develops - a large amount of urine production, and the urine does not taste sweet. Previously, they actually tasted urine and made a diagnosis: if it was sweet, it was diabetes, and if it was not, diabetes insipidus.

Oxytocin– target organs – myometrium and myoepithelium of the mammary gland.

1. Myoepithelium of the mammary gland: after childbirth, milk begins to be released within 24 hours. The nipples of the breast become very irritated during the act of sucking. Irritation goes to the brain, where the release of oxytocin is stimulated, affecting the myoepithelium of the mammary gland. This is a muscular epithelium located paraalveolarly, and when contracted, squeezes milk out of the mammary gland. Lactation stops more slowly in the presence of a baby than in its absence.

2. Myometrium: when the cervix and vagina are irritated, the production of oxytocin is stimulated, which causes the myometrium to contract, pushing the fetus to the cervix, from the mechanoreceptors of which the irritation again enters the brain and stimulates even greater production of oxytocin. This process ultimately progresses to childbirth.

An interesting fact is that oxytocin is also released in men, but its role is not clear. Perhaps it stimulates the muscle that lifts the testicle during ejaculation.

Adenohypophysis. Let us immediately indicate the pathological moment in the phylogenesis of the adenohypophysis. During embryogenesis, it is formed in the area of the primary oral cavity, and then moves to the sella turcica. This can lead to the fact that particles of nervous tissue may remain on the path of movement, which during life can begin to develop as ectoderm and give rise to tumor processes in the head area. The adenohypophysis itself has the origin of glandular epithelium (reflected in the name).

The adenohypophysis secretes 6 hormones(shown in the table).

Glandotropic hormones- These are hormones whose target organs are endocrine glands. The release of these hormones stimulates the activity of the glands.

Gonadotropic hormones– hormones that stimulate the functioning of the gonads (genital organs). FSH stimulates follicle maturation in the ovaries in women and sperm maturation in men. And LH (lutein is a pigment belonging to the group of oxygen-containing carotenoids - xanthophylls; xanthos - yellow) causes ovulation and the formation of the corpus luteum in women, and in men it stimulates the synthesis of testosterone in the interstitial Leydig cells.

Effector hormones– affect the entire body as a whole or its systems. Prolactin involved in lactation; other functions are likely present but are not known in humans.

Secretion somatotropin caused by the following factors: hypoglycemia of fasting, certain types of stress, physical work. The hormone is released during deep sleep and, in addition, the pituitary gland occasionally secretes large amounts of this hormone in the absence of stimulation. The hormone affects growth indirectly, causing the formation of liver hormones - somatomedins. They affect bone and cartilage tissue, promoting their absorption of inorganic ions. The main one is somatomedin C, stimulating protein synthesis in all cells of the body. The hormone directly affects metabolism, mobilizing fatty acids from fat reserves and facilitating the entry of additional energy material into the blood. I draw the attention of the girls to the fact that the production of somatotropin is stimulated by physical activity, and somatotropin has a lipomobilizing effect. On carbohydrate metabolism, GH has two opposite effects. One day after the administration of growth hormone, the concentration of glucose in the blood drops sharply (insulin-like effect of somatomedin C), but then the glucose concentration begins to increase as a result of the direct effect of GH on adipose tissue and glycogen. At the same time inhibiting the uptake of glucose by cells. Thus, there is a diabetogenic effect. Hypofunction causes normal dwarfism, hyperfunction gigantism in children and acromegaly in adults.

The regulation of the secretion of hormones by the pituitary gland, as it turned out, is more difficult than expected. Previously, it was believed that each hormone had its own liberin and statin.

But it turned out that the secretion of some hormones is stimulated only by liberin, while the secretion of two others is stimulated only by liberin (see table 17.2).

Hypothalamic hormones are synthesized through the occurrence of APs on nuclear neurons. The strongest PDs come from the midbrain and limbic system, particularly the hippocampus and amygdala through noradrenergic, adrenergic and serotonergic neurons. This allows you to integrate external and internal influences and emotional state with neuroendocrine regulation.

Conclusion

All that remains to be said is that such a complex system must work like a clock. And the slightest failure can lead to disruption of the entire body. It’s not for nothing that they say: “All diseases come from nerves.”

References

1. Ed. Schmidt, Human Physiology, 2nd volume, p.389

2. Kositsky, human physiology, p. 183

mybiblioteka.su - 2015-2018. (0.097 sec.)

Humoral mechanisms regulating the physiological functions of the body

In the process of evolution, humoral regulatory mechanisms were the first to be formed. They arose at the stage when blood and circulation appeared. Humoral regulation (from Latin humor- liquid), this is a mechanism for coordinating the vital processes of the body, carried out through liquid media - blood, lymph, interstitial fluid and cell cytoplasm with the help of biologically active substances. Hormones play an important role in humoral regulation. In highly developed animals and humans, humoral regulation is subordinated to nervous regulation, together with which they form a unified system of neurohumoral regulation that ensures the normal functioning of the body.

The body fluids are:

— extravasar (intracellular and interstitial fluid);

— intravasar (blood and lymph)

- specialized (CSF - cerebrospinal fluid in the ventricles of the brain, synovial fluid - lubrication of joint capsules, liquid media of the eyeball and inner ear).

All basic life processes, all stages of individual development, and all types of cellular metabolism are under the control of hormones.

The following biologically active substances participate in humoral regulation:

— vitamins, amino acids, electrolytes, etc. supplied with food;

- hormones produced by endocrine glands;

— CO2, amines and mediators formed in the process of metabolism;

- tissue substances - prostaglandins, kinins, peptides.

Hormones. The most important specialized chemical regulators are hormones. They are produced in the endocrine glands (endocrine glands, from the Greek. endo– inside, krino- highlight).

There are two types of endocrine glands:

- with a mixed function - internal and external secretion, this group includes the sex glands (gonads) and the pancreas;

- with the function of organs only of internal secretion, this group includes the pituitary gland, pineal gland, adrenal glands, thyroid and parathyroid glands.

The transmission of information and regulation of the body’s activities is carried out by the central nervous system with the help of hormones. The central nervous system exerts its influence on the endocrine glands through the hypothalamus, in which regulatory centers and special neurons are located that produce hormone intermediaries - releasing hormones, with the help of which the activity of the main endocrine gland - the pituitary gland - is regulated. The emerging optimal concentrations of hormones in the blood are called hormonal status .

Hormones are produced in secretory cells. They are stored in granules inside cellular organelles, separated from the cytoplasm by a membrane. Based on their chemical structure, they distinguish between protein (derivatives of proteins, polypeptides), amine (derivatives of amino acids) and steroid (derivatives of cholesterol) hormones.

Hormones are classified according to their functional characteristics:

- effector– act directly on target organs;

- tropic– produced in the pituitary gland and stimulate the synthesis and release of effector hormones;

—releasing hormones (liberins and statins), they are secreted directly by the cells of the hypothalamus and regulate the synthesis and secretion of tropic hormones. Through releasing hormones, they communicate between the endocrine and central nervous systems.

All hormones have the following properties:

- strict specificity of action (it is associated with the presence in target organs of highly specific receptors, special proteins to which hormones bind);

— distance of action (target organs are located far from the place of hormone formation)

The mechanism of action of hormones. It is based on: stimulation or inhibition of the catalytic activity of enzymes; changes in the permeability of cell membranes. There are three mechanisms: membrane, membrane-intracellular, intracellular (cytosolic.)

Membrane– ensures the binding of hormones to the cell membrane and, at the site of binding, changes its permeability to glucose, amino acids and some ions. For example, the pancreatic hormone insulin increases glucose transport through the membranes of liver and muscle cells, where glucagon is synthesized from glucose (Fig **)

Membrane-intracellular. Hormones do not penetrate the cell, but influence metabolism through intracellular chemical intermediaries. Protein-peptide hormones and amino acid derivatives have this effect. Cyclic nucleotides act as intracellular chemical messengers: cyclic 3′,5′-adenosine monophosphate (cAMP) and cyclic 3′,5′-guanosine monophosphate (cGMP), as well as prostaglandins and calcium ions (Figure **).

Hormones influence the formation of cyclic nucleotides through the enzymes adenylate cyclase (for cAMP) and guanylate cyclase (for cGMP). Adeilate cyclase is built into the cell membrane and consists of 3 parts: receptor (R), conjugating (N), catalytic (C).

The receptor part includes a set of membrane receptors that are located on the outer surface of the membrane. The catalytic part is an enzyme protein, i.e. adenylate cyclase itself, which converts ATP into cAMP. The mechanism of action of adenylate cyclase is as follows. After the hormone binds to the receptor, a hormone-receptor complex is formed, then the N-protein-GTP (guanosine triphosphate) complex is formed, which activates the catalytic part of adenylate cyclase. The coupling part is represented by a special N-protein located in the lipid layer of the membrane. Activation of adenylate cyclase leads to the formation of cAMP inside the cell from ATP.

Under the influence of cAMP and cGMP, protein kinases are activated, which are in the inactive state in the cytoplasm of the cell (Figure **)

In turn, activated protein kinases activate intracellular enzymes, which, acting on DNA, participate in the processes of gene transcription and synthesis of the necessary enzymes.

Intracellular (cytosolic) mechanism action is typical for steroid hormones, which have smaller molecules than protein hormones. In turn, they are related to lipophilic substances in terms of physicochemical properties, which allows them to easily penetrate the lipid layer of the plasma membrane.

Having penetrated into the cell, the steroid hormone interacts with a specific receptor protein (R) located in the cytoplasm, forming a hormone-receptor complex (GRa). This complex in the cytoplasm of the cell undergoes activation and penetrates through the nuclear membrane to the chromosomes of the nucleus, interacting with them. In this case, gene activation occurs, accompanied by the formation of RNA, which leads to enhanced synthesis of the corresponding enzymes. In this case, the receptor protein serves as an intermediary in the action of the hormone, but it acquires these properties only after it is combined with the hormone.

Along with the direct influence on the enzyme systems of tissues, the effect of hormones on the structure and functions of the body can be carried out in more complex ways with the participation of the nervous system.

Humoral regulation and vital processes

In this case, hormones act on interoreceptors (chemoreceptors) located in the walls of blood vessels. Irritation of chemoreceptors serves as the beginning of a reflex reaction, which changes the functional state of the nerve centers.

The physiological effects of hormones are very diverse. They have a pronounced effect on metabolism, differentiation of tissues and organs, growth and development. Hormones are involved in the regulation and integration of many body functions, adapting it to changing conditions of the internal and external environment, and maintaining homeostasis.

Human biology

Textbook for 8th grade

Humoral regulation

Various life support processes constantly occur in the human body. Thus, during the waking period, all organ systems function simultaneously: a person moves, breathes, blood flows through his vessels, digestion processes take place in the stomach and intestines, thermoregulation takes place, etc. A person perceives all changes occurring in the environment and reacts to them. All these processes are regulated and controlled by the nervous system and the 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 the neurons of the diencephalon enter the posterior lobe of the pituitary gland along the stalk. 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 stress, i.e. under stress: these hormones enhance muscle work, increase blood glucose (to ensure increased energy expenditure of the brain), and increase blood flow in the brain and other vital organs, increase the level of systemic blood pressure, and enhance 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 that enters 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 does not have enough “fuel”, the person goes into so-called insulin shock and loses consciousness. In this case, it is necessary to quickly introduce glucose into the blood.

The gonads form germ cells and produce hormones that regulate the growth and maturation of the body and the formation of secondary sexual characteristics. In men, this is the growth of a mustache and beard, a deepening of the voice, a change in physique; in women, a high voice, roundness of body shape. Sex hormones determine the development of the genital organs, the maturation of germ cells; in women they control the phases of the sexual cycle and the course of pregnancy.

Structure of the thyroid gland

The thyroid gland is one of the most important internal secretion organs. A 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 towards 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 removal of this organ.

In 1896, A. Bauman established a high iodine content in iron and drew the attention of researchers to the fact that even the ancient Chinese successfully treated cretinism with the ashes of sea sponges, which contained 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, and heart rate sharply increase, 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, iodine consumption by the population should be increased, which can be achieved, for example, by using table salt with the obligatory 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 adopted by the World Health Organization when defining various vital parameters), 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 growth has already ceased, the disease acromegaly occurs, in which the nose, lips, fingers and toes and some other parts of the body grow.

Test your knowledge

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

Think

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

Direction of the process in humoral regulation

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.

Nervous and humoral regulation

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 released into the internal environment of the body (lymph, blood, tissue fluid).

Humoral regulation can be carried out with the help of:

hormones- biologically active (acting in a very small concentration) substances released into the blood by the endocrine glands;
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: thyroid gland, pituitary gland, adrenal glands.

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 pancreas secretes insulin and glucagon into the blood, and not into the blood (into the duodenum) - pancreatic juice;
sexual The glands secrete sex hormones into the blood, but not into the blood - sex cells.

MORE INFORMATION: Humoral regulation, Types of glands, Types of hormones, timing and mechanisms of their action, Maintaining blood glucose concentrations
TASKS PART 2: Nervous and humoral regulation

Tests and assignments

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

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) stimulation of the respiratory center in the medulla oblongata
3) transmission of impulse to the intercostal muscles and diaphragm
4) increased oxidative processes during active muscle work
5) inhalation and air entering the lungs

Establish a correspondence between the process that occurs during human breathing and the method of its regulation: 1) humoral, 2) nervous
A) stimulation 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

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

2. Establish a correspondence between the characteristics of the glands and their type: 1) external secretion, 2) internal secretion.

Humoral regulation of the body

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

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

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

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

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

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

Choose one, the most 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

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

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 body’s reaction to changes in body position in space
5) release of adrenaline during stress

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) stopping 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

Select three endocrine glands.
1) pituitary gland
2) sexual
3) adrenal glands
4) thyroid
5) stomach
6) dairy

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