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Female reproductive system:
Ovarian-menstrual cycle; age-related changes; hormonal regulation

sexual cycle

The ovarian-menstrual cycle is a successive change in the function and structure of the organs of the female reproductive system, regularly repeating in the same order. In women and female great apes, the sexual cycles are characterized by regular uterine bleeding (menstruation).

In most women who have reached puberty, menstruation is repeated regularly every other 28 days. In the ovarian-menstrual cycle, three periods or phases are distinguished: the menstrual (endometrial desquamation phase), which ends the previous menstrual cycle, the postmenstrual period (endometrial proliferation phase) and, finally, the premenstrual period (functional phase, or secretion phase), during which preparation of the endometrium for possible implantation of the embryo if fertilization has occurred.

menstrual period. It consists in desquamation, or rejection, of the functional layer. In the absence of fertilization, the intensity of secretion of progesterone by the corpus luteum decreases sharply. As a result, the spiral arteries that feed the functional layer of the endometrium spasm. In the future, non-rotic changes and rejection of the functional layer of the endometrium occur.

The basal layer of the endometrium, fed by the direct arteries, continues to be supplied with blood and is the source for the regeneration of the functional layer in the next phase of the cycle.

On the day of menstruation, there are practically no ovarian hormones in the body of a woman, since the secretion of progesterone stops, and the secretion of estrogens (which was prevented by the corpus luteum while it was in its prime) has not yet resumed.

Regression of the corpus luteum disinhibits the growth of the next follicle - estrogen production is restored. Under their influence, the regeneration of the endometrium is activated in the uterus - the proliferation of the epithelium is enhanced due to the bottoms of the uterine glands, which are preserved in the basal layer after desquamation of the functional layer. After 2-3 days of proliferation, menstrual bleeding stops and the next postmenstrual period begins. Thus, the postmenstrual phase is determined by the influence of estrogen, and the premenstrual phase by the influence of progesterone.

postmenstrual period. This period begins after the end of menstruation. At this moment, the endometrium is represented only by the basal layer, in which the distal sections of the uterine glands remain. The regeneration of the functional layer that has already begun allows us to call this period the proliferation phase. It continues from the 5th to the 14th ... 15th day of the cycle. The proliferation of the regenerating endometrium is most intense at the beginning of this phase (5...11th day of the cycle), then the rate of regeneration slows down and a period of relative rest begins (11...14th day). The uterine glands in the postmenstrual period grow rapidly, but remain narrow, straight and do not secrete.

As already mentioned, endometrial growth is stimulated by estrogens, which are produced by growing follicles. Therefore, during the postmenstrual period, another follicle grows in the ovary, which reaches the mature stage (tertiary, or vesicular) by the 14th day of the cycle.

Ovulation occurs in the ovary on the 12th ... 17th day of the menstrual cycle, i.e. approximately halfway between two consecutive periods. In connection with the participation of ovarian hormones in the regulation of uterine restructuring, the described process is usually called not the menstrual cycle, but the ovarian-menstrual cycle.

premenstrual period. At the end of the postmenstrual period, ovulation occurs in the ovary, and in place of the bursting vesicular follicle, a corpus luteum is formed that produces progesterone, which activates the uterine glands, which begin to secrete. They increase in size, become convoluted and often branch out. Their cells swell, and the gaps of the glands are filled with secretions. Vacuoles containing glycogen and glycoproteins appear in the cytoplasm, first in the basal part, and then shifting to the apical edge. Mucus, abundantly secreted by the glands, becomes thick. In areas of the epithelium lining the uterine cavity between the mouths of the uterine glands, the cells acquire a prismatic shape, and cilia develop on the tops of many of them. The thickness of the endometrium increases compared to the previous postmenstrual period, which is due to hyperemia and the accumulation of edematous fluid in the lamina propria. Lumps of glycogen and lipid droplets are also deposited in the cells of the connective tissue stroma. Some of these cells differentiate into decidual cells.

If fertilization occurs, then the endometrium is involved in the formation of the placenta. If fertilization did not take place, then the functional layer of the endometrium is destroyed and rejected during the next menstruation.

Cyclic changes in the vagina. With the onset of endometrial proliferation (on the 4-5th day after the end of menstruation), i.e. in the postmenstrual period, epithelial cells noticeably swell in the vagina. On the 7-8th day, an intermediate layer of compacted cells differentiates in this epithelium, and by the 12-14th day of the cycle (towards the end of the postmenstrual period), the cells in the basal layer of the epithelium strongly swell and increase in volume. In the upper (functional) layer of the vaginal epithelium, the cells loosen and clumps of keratohyalin accumulate in them. However, the process of keratinization does not reach full keratinization.

In the premenstrual period, the deformed compacted cells of the functional layer of the vaginal epithelium continue to be rejected, and the cells of the basal layer become denser.

The condition of the epithelium of the vagina depends on the level of ovarian hormones in the blood, so the picture of the vaginal smear can be used to judge the phase of the menstrual cycle and its violations.

Vaginal smears contain desquamated epitheliocytes, there may be blood cells - leukocytes and erythrocytes. Among epitheliocytes, cells that are at various stages of differentiation are distinguished - basophilic, acidophilic and intermediate. The ratio of the number of the above cells varies depending on the phase of the ovarian-menstrual cycle. In the early, proliferative phase (7th day of the cycle), superficial basophilic epitheliocytes predominate; large nuclei and leukocytes; in the menstrual phase, the number of blood cells - leukocytes and erythrocytes - increases significantly.

During menstruation, erythrocytes and neutrophils predominate in the smear, epithelial cells are found in small numbers. At the beginning of the postmenstrual period (in the proliferative phase of the cycle), the vaginal epithelium is relatively thin, and the content of leukocytes in the smear decreases rapidly and epithelial cells with pycnotic nuclei appear. By the time of ovulation (in the middle of the ovarian-menstrual cycle), such cells in the smear become predominant, and the thickness of the vaginal epithelium increases. Finally, in the premenstrual phase of the cycle, the number of cells with a pyknotic nucleus decreases, but the desquamation of the underlying layers increases, the cells of which are found in the smear. Before the onset of menstruation, the content of red blood cells in the smear begins to increase.

Age-related changes in the organs of the female reproductive system

The morphofunctional state of the organs of the female reproductive system depends on the age and activity of the neuroendocrine system.

Uterus. In a newborn girl, the length of the uterus does not exceed 3 cm and, gradually increasing during the prepubertal period, reaches its final size upon reaching puberty.

By the end of the childbearing period and in connection with the approach of menopause, when the hormone-forming activity of the ovaries weakens, involutive changes begin in the uterus, primarily in the endometrium. Deficiency of luteinizing hormone in the transitional (premenopausal) period is manifested by the fact that the uterine glands, while still retaining the ability to grow, already cease to function. After the establishment of menopause, endometrial atrophy progresses rapidly, especially in the functional layer. In parallel, atrophy of muscle cells develops in the myometrium, accompanied by hyperplasia of the connective tissue. In this regard, the size and weight of the uterus, undergoing age-related involution, are significantly reduced. The onset of menopause is characterized by a decrease in the size of the organ and the number of myocytes in it, and sclerotic changes occur in the blood vessels. This is a consequence of a decrease in hormone production in the ovaries.

Ovaries. In the first years of life, the size of the ovaries in a girl increases mainly due to the growth of the brain part. Atresia of the follicles, progressing in childhood, is accompanied by proliferation of connective tissue, and after 30 years, proliferation of connective tissue also captures the cortical substance of the ovary.

The attenuation of the menstrual cycle in the menopause is characterized by a decrease in the size of the ovaries and the disappearance of follicles in them, sclerotic changes in their blood vessels. Due to insufficient production of lutropin, ovulation and the formation of corpus luteum do not occur, and therefore the ovarian-menstrual cycles first become anovulatory, and then stop and occur. menopause.

Vagina. Morphogenetic and histogenetic processes leading to the formation of the main structural elements of the organ are completed by the period of puberty.

After the onset of menopause, the vagina undergoes atrophic changes, its lumen narrows, the mucosal folds smooth out, and the amount of vaginal mucus decreases. The mucous membrane is reduced to 4...5 layers of cells that do not contain glycogen. These changes create conditions for the development of infection (senile vaginitis).

Hormonal regulation of the activity of the female reproductive system

Clitoris in embryonic development and structure corresponds to the dorsal part of the male penis. It consists of two erectile cavernous bodies ending in a head, which is covered with a stratified squamous epithelium, slightly keratinized.

Innervation. The external genital organs, especially the clitoris, are richly supplied with various. In the epithelium of these organs, free nerve endings branch out. In the connective tissue papillae of the lamina propria of their mucous membrane there are tactile nerve bodies, and in the dermis - encapsulated genital bodies. Lamellar bodies are also found in the large lips and clitoris.

Milk glands

The histofunctional characteristics of the mammary glands are given earlier, in the topic.

Some terms from practical medicine:

• menopause, menopause, climacteric ( climax; Greek klimax stairs; climacterium; Greek klimakter step (stairs), turning point) - the period of life (both men and women), during which the cessation of the generative function occurs;
• menopause (menopause; Meno-Greek men month + Greek pause termination, break) - the second phase of the menopause, which occurs after the last menstrual-like bleeding and is characterized by the cessation of cyclic changes in the endometrium and reproductive function, progressive involution of the genital organs and a decrease in the secretion of sex hormones;
• menophobia (menophobia; meno- + phobia) - obsessive fear - fear of menstruation and (or) associated discomfort;
• vaginismus (vaginismus; lat. vagina vagina; synonym: vulvism, colpospasm) - reflex spastic contraction of the muscles of the vestibule of the vagina and the pelvic floor, which makes it difficult to have sexual intercourse or gynecological examination;
• vulvovaginitis (vulvovaginitis; vulva - female external genitalia + lat. vagina vagina + -it) - inflammation of the female external genitalia and vagina;
• colpitis -- (colpitis; colp - Greek kolpos deepening, sinus, vagina + -itis, synonym: vaginitis, endocolpitis) - inflammation of the vaginal mucosa;

The secretion of female sex steroid hormones (estrogens and progesterone), as well as ovogenesis and ovulation, occur in the ovaries cyclically - within the framework of the ovarian cycle with an average duration of 28 days. Fluctuations from 21 to 32 days are possible. Menstrual the cycle ensures the integration in time of various processes necessary for reproductive function: egg maturation and ovulation, periodic preparation of the endometrium for implantation of a fertilized egg, changes in the woman's body, including behavior.

Ovarian the cycle consists of three phases: follicular (from the 1st to the 14th day of the cycle), ovulatory (13th day of the cycle) and luteal (from the 15th to the 28th day of the cycle). After the completion of the previous cycle, the new follicle is included in the new cycle. The growth of the follicle occurs under the influence of the pituitary follicle-stimulating hormone (FSH) - the follicular phase. At this time, the formation of the outer and inner membranes of the follicle occurs, the egg grows and matures. Envelope cells increase as they grow estrogen synthesis, the concentration of estrogen depends not only on FSH, but also on LH and increases towards the middle of the cycle.

It is estrogens that determine the changes that occur in a woman's body in the first half of the cycle. Consider their effects in relation to various organs. First of all, estrogens enhance the growth and development of the egg and the follicle itself. In the uterus, under the influence of hormones, the proliferative phase begins, during which the thickening of the endometrial mucosa and the development of its glands occur. In the hypothalamus in the first quarter of the cycle, under the influence of small concentrations of hormones, the secretion of FSH and LH increases, at the peak of estrogen concentration - the middle of the cycle - the secretion of FSH is suppressed.

Table 1

Effects of estrogens

in the ovaries	· Growth and development of the ovaries themselves · Formation of follicles · Increased sensitivity of follicles to gonadotropins (FSH and LH) and prolactin · Increase in the number of estrogen receptors.
In the uterus	Growth of the endometrium and myometrium. Early effects - 15 min - 8 hours: increase in RNA polymerase activity, release of prostaglandins, watering, increase in the concentration of growth factors, accumulation of eosinophils from the blood. Late effects 6 - 28 hours: increase in the amount of RNA polymerase, protein synthesis, proliferation of myometrial and endometrial cells · Increased contractility of the myometrium. · Increased sensitivity to progesterone associated with increased synthesis of receptors. Increase in the number of receptors for oxytocin and NA.
In the mammary glands	Growth of mammary ducts
In the brain	· Estrogens are the main inducers of sexual differentiation of the hypothalamus and pituitary gland. The preovulatory rise in estrogen levels enhances the secretion of gonadoliberins, increases the sensitivity of gonadotropes to their action. The influence of estrogens on the ventromedial nuclei causes the corresponding sexual behavior.
In other organs	In the liver, the synthesis of hormone carrier proteins increases. In the kidneys, an increase in ARP (plasma renin activity), therefore, sodium and water retention. The anabolic effect, however, is much weaker than the effects of androgens Increased fat deposition

The follicular phase of the cycle ends with ovulation, which occurs at the peak of LH secretion, note that without luteinizing hormone, ovulation does not occur, in which case the cycle becomes anovulatory. After ovulation, the corpus luteum of the ovary, which develops at the site of the burst follicle, begins to produce a hormone - progesterone. Progesterone secretion is regulated by LH. The main function of progesterone is to prepare the endometrium for implantation of a fertilized egg and ensure the normal course of pregnancy. If fertilization does not occur, the corpus luteum degenerates.

Progesterone together with estrogen regulates morphological changes in the uterus and mammary glands, enhancing the processes of proliferation and secretory activity. As a result, in the secretion of the endometrial glands, the concentrations of lipids and glycogen, which are necessary for the development of the embryo, increase. Progesterone enhances hyperplasia and hypertrophy of the myometrium during pregnancy and reduces the excitability of the uterus. In non-pregnant women, progesterone is involved in the regulation of the menstrual cycle. The hormone promotes the growth of alveoli in the mammary glands. In the hypothalamus, high concentrations of progesterone suppress the secretion of all tropic hormones: FSH, LH, PRl. That is why bleeding occurs - the rejection of a new mucous layer with blood vessels. In the brain, under the influence of progesterone, a decrease in excitability is observed. Progesterone enhances basal metabolism and increases basal body temperature, which is used in practice to determine the time of ovulation.

The regulation of the menstrual cycle is carried out by gonadoliberin and gonadotropins.

GONADOLIBERIN - a hypothalamic decapeptide that regulates the secretion of both follicle-stimulating (FSH) and luteinizing (LH) hormones. The ability of GL in some cases to stimulate the synthesis and release of FSH, and in others LH is explained by the modulating effect of sex hormones (different levels during the sexual cycle) and the participation of prostaglandins.

GONADOTROPINS - adenohypophysis hormones - follicle-stimulating (FSH) and luteinizing (LH).

In women with the onset of puberty, ovulation is periodically repeated.

female sexual cycle lasts 27-28 days. It is divided into four periods:

1. preovulatory (praeoestrus),
2. ovulation (rus),
3. post-ovulation (metaoestrus),
4. dormant period (dioestrus).

Pre-ovulatory period

During this period, preparation for pregnancy takes place. In many animal species with seasonal mating, the pre-ovulation period is also the period of preparation of the female reproductive apparatus for sexual intercourse. During this period, they have estrus and the female allows the male to commit this act.

In the pre-ovulation period, the following changes are observed in women: the uterus increases in size and becomes full-blooded; the lining of the uterus and its glands grow; there comes an increase and an increase in peristaltic contractions of the fallopian tubes and the muscular layer of the uterus; the vaginal mucosa grows and the number of desquamated epithelial cells increases in the vaginal mucus.

The cause of the emerging changes is the increased secretion of follicle-stimulating hormone from the pituitary gland.

This hormone also acts on immature female animals: if they are given increasing amounts of an extract from the anterior pituitary gland, or follicle-stimulating hormone, from day to day, then they develop changes characteristic of the preovulatory period in the uterus and vagina, and ovulation may occur. If in sexually mature female animals the pituitary gland is surgically removed at the beginning of the preovulation period, then the further development of preovulatory changes in the uterus and vagina stops and ovulation does not occur.

All preovulatory changes are caused by pituitary gonadotropic hormones through their effect on the intrasecretory function of the ovaries. In the ovaries at this time, there is an increased production of estrogens, which stimulate the growth of the uterus and its mucous membrane, the proliferation of the mucous epithelium of the vagina and increase the contraction of the uterus and fallopian tubes. If administered over several days to women who, for medical reasons, have had their ovaries removed and, as a result, there is no sexual cycle, increasing amounts of estrogen, then they experience typical pre-ovulatory changes in the uterus and vagina.

In the normal body, the gradually increasing FSH accelerates the final maturation of the most mature of the Graafian vesicles. The surface of this Graafian vesicle ruptures and an egg is released from it, in other words, ovulation occurs.

ovulation period

This period begins with the rupture of the Graafian vesicle, the release of the egg from it and its movement through the fallopian tube into the uterus. During the passage of the egg through the fallopian tube, fertilization occurs. A fertilized egg, getting into the uterus, is attached to its mucous membrane. The sexual cycle is interrupted and pregnancy occurs. After the release of the egg, a corpus luteum begins to develop in place of the burst Graafian vesicle. The hormone produced by the cells of the corpus luteum is no longer estrogen, but progesterone. This, of course, does not mean that the production of estrogen in the ovaries has ceased: it is still secreted by numerous other maturing follicles.

The egg, released from the bursting Graafian vesicle, enters the fallopian tube, guided into it by the movements of the ciliated epithelium lining the fimbria of the tube hanging over the ovary. The contractions of the smooth muscles of the tubes at this time are enhanced under the influence of an increased amount of estrogen in the blood. Due to this, the egg is pushed through the tube quite quickly at first. As the developing corpus luteum secretes more and more testerone in the ovary, peristaltic contractions of the tubes become less frequent and weaker, as progesterone counteracts the stimulating effect of estrogen on the contractions of the muscles of the tubes and uterus. In general, it takes about three days to bring the egg through the tube to the uterus. If fertilization of the cell does not occur, the post-ovulation period begins.

Post-ovulation period

Women during this period have menstruation. Animals (with the exception of monkeys) do not menstruate.

An unfertilized egg, having entered the uterus, remains alive for several days, and then dies. Meanwhile, under the influence of progesterone, the release of gonadotropic hormones by the anterior pituitary gland decreases.

The decrease in the follicle-stimulating hormone of the pituitary gland leads to a decrease in the formation of estrogens in the ovaries, therefore, the factor that caused and maintained the preovulatory changes in the tubes, uterus and vagina drops out. The decrease in the luteinizing hormone of the pituitary gland causes atrophy of the corpus luteum with its replacement by a connective tissue scar, as a result of which the ovarian production of progesterone stops. Preovulatory changes in the uterus, tubes and vagina begin to decrease.

In this period, due to a decrease in the blood of ovarian hormones, tonic contractions of the uterus increase, leading to the rejection of its mucous membrane. Scraps of the latter come out with the blood - menstrual bleeding occurs, after which there is a rapid regeneration of the uterine mucosa.

At the end of the post-ovulation period, a period of inter-ovulation rest begins, followed by the pre-ovulation period of a new cycle.

The sexual cycle is also called the menstrual cycle. These are changes occurring periodically in the body of a woman of reproductive age, which are aimed at the probable possibility of conception. In medicine, the first day of menstruation is considered to be the beginning of the menstrual cycle. In total, it includes three phases, which we will discuss in this article. These are proliferative, menstrual and secretory. If in animals females are capable of sexual behavior at any time, then in humans, after about five hundred cycles, menopause occurs. This occurs between the ages of 46 and 54. In this condition, the ovaries become insensitive to luteotropin and follitropin.

Duration

The duration of the sexual cycle in women can be different. The physiological processes taking place in her body are of decisive importance. At the same time, there are approximate deadlines in which it should fit. If this does not happen, then there is reason to suspect various violations.

The duration of the sexual cycle in a woman is 28 days. Depending on various factors, it can vary, becoming a week longer or shorter.

First menstruation

To understand the concept of the sexual cycle, one should delve into the specialized terminology related to this condition. This article will discuss the main terms.

The central event in the process of sexual development of every woman is the menarche. This is the first sexual cycle in her life. It indicates that the body is now ready for reproduction. As a rule, in women, menarche occurs at the age of twelve to fourteen years. The norm is considered to be between the ages of nine and fifteen.

With the appearance of menstruation at the age of nine, they speak of early menarche, and at 15 years of age - of primary amenorrhea. The time at which the first menstrual bleeding occurs depends on many factors. This is nutrition, heredity, the general health of the girl.

Possible violations

Violations of the sexual cycle can be caused by a large number of different factors. These are pregnancy, hormonal disruptions in adolescence, and other natural causes. The menstrual cycle can also go astray due to internal and external stresses.

It is customary to talk about a delay in menstruation if there are no cyclic bleeding within 35 days. It should be noted that small delays in menstruation are considered normal. However, only if their duration does not exceed ten days.

One of the most common reasons for missed periods is pregnancy. In this case, a test should be purchased to confirm. If the result is negative, you should consult a gynecologist. He will understand the causes and, if necessary, prescribe the appropriate treatment.

The causes of violations of the regulation of the sexual cycle can be a large number:

• neurological and mental diseases;
• mental shocks;
• obesity;
• avitaminosis;
• infectious diseases;
• liver problems;
• diseases of the hematopoietic system, blood vessels or heart;
• consequences of gynecological operations;
• violation of puberty;
• urinary tract injury;
• genetic diseases;
• hormonal changes that occur during menopause.

It is worth noting that in adolescents, a delay in menstruation is a common occurrence. In the first couple of years after the onset of menstruation, girls rarely experience a constant cycle. In this case, do not worry, this is a common occurrence. It is due to the fact that at this age the hormonal background is still unstable, so ups and downs in mood are likely, which leads to a significant increase or decrease in the level of hormones in the blood. When the hormones stop raging, the cycle immediately stabilizes. If it does not become regular two years after the onset of menstruation, you should consult a gynecologist for help.

Climax

Termination of regular periods of the sexual cycle occurs during menopause. This is characterized by the extinction of the reproductive function. Irregular periods or their complete cessation is called menopause.

When this time comes, mainly depends on heredity. Medical interventions, in particular, gynecological operations, and certain diseases, can also have an impact. All these problems can lead to early menopause.

Phases

The processes that occur during menstruation make up the phases of the sexual cycle, they are also called stages.

They correspond to the changes that occur in the ovaries and endometrium, that is, the internal mucous membrane of the uterus that lines its cavity.

Follicular phase

The first stage of the sexual cycle is called the menstrual or follicular. At this stage, the woman begins to bleed from the uterus. This happens due to the rejection of the endometrial layer, which is abundantly supplied with blood vessels.

Rejection begins at the end of the ovarian cycle. It occurs necessarily only if the egg has not been fertilized. The beginning of the first stage of the sexual cycle or the follicular phase of the ovary is considered the very first day of menstruation. The duration of this period may be different, for each woman it is individual. During this time, the dominant follicle should finally mature. On average, it is two weeks, but the time interval from seven to 22 days is considered the norm.

The course of the menstrual cycle

The follicular phase and the accompanying ovarian cycle begin with the release of GnRH by the hypothalamus. It actively stimulates the pituitary gland to secrete small amounts of luteinizing and follicle-stimulating hormones. These are, respectively, lutropin and follitropin.

Due to the reduced level of estradiol secretion, the release of lutropin and follitropin is suppressed. As a result, their level of education remains low.

Under the influence of follitropin, several follicles begin to develop in the ovaries at once. Of these, the dominant follicle stands out, which has the maximum number of receptors for folliculotropin. In addition, it most intensively synthesizes estradiol. The rest at the same time undergo atresia, that is, the reverse development of follicles in the ovary.

Over time, the level of estradiol in the body begins to rise. At its low concentration, the secretion of gonadotropins is suppressed, and at a high one, on the contrary, it is stimulated. As a result, these processes lead to a significant release of GnRH by the hypothalamus.

This effect is especially pronounced for lutropin, since a high concentration of estradiol increases the sensitivity of adenohypophysis cells. In addition, follicles react much more intensively to lutropin due to the presence of a larger number of receptors for this hormone.

The result of this is regulation according to the principle of positive feedback. The follicle continues to increase in size exactly until a sharp release of lutropin begins. This means the end of the follicular phase.

ovulatory phase

The new phase is called ovulatory or proliferative. Around the end of the first week of the cycle, the dominant follicle is released. It continues to grow steadily, and also increases the amount of estradiol. At this time, the remaining follicles undergo reverse development.

The follicle, which finally matures and is ready for ovulation, is scientifically called the Graafian vesicle. It is worth noting that the ovulatory phase lasts only about three days. During this time, the main release of luteinizing hormone occurs.

Hormone release

Within one and a half to two days, several waves of release of this hormone happen in a row at once, its concentration in the plasma at this time increases significantly. The release of luteinizing hormone is the final stage of follicle development. In addition, it stimulates the production of proteolytic enzymes and prostaglandins, which are required to break the wall of the follicle and release the egg. This is the process of ovulation itself.

In parallel, the level of estradiol in the body begins to fall. A feature of the sexual cycle is that in some cases it may be accompanied by ovulatory syndrome. It is characterized by painful and uncomfortable sensations in the abdomen, iliac regions.

As a rule, ovulation occurs within a day after the maximum wave of luteinizing hormone release. A period of 16 hours to two days is considered the norm. This is an important part of the sexual reproduction cycle.

During ovulation, a woman's body releases from 5 to 10 ml of follicular fluid, which contains the egg necessary for conception.

secretory phase

This phase of menstruation is also called the luteal phase. This is the period of time between ovulation and the onset of the next menstrual bleeding. It is also known as the corpus luteum phase. Unlike the previous follicular phase, the duration of this stage is considered to be more constant. It is from 13 to 14 days, normally it can be more or less by two days.

When the Graafian vesicle ruptures, its walls immediately fall off, and the luteal pigment and lipids penetrate into the cells. Due to this, it acquires a characteristic yellow color. After transformation, the follicle is already called the corpus luteum.

In total, the duration of the luteal phase depends on the period of functioning of the corpus luteum. As a rule, it is ten to twelve days. At this time, it secretes estradiol, progesterone and androgens. In the presence of elevated levels of progesterone and estrogen, the outer layers of the endometrium change. Her glands mature, begin to secrete and proliferate. This is a clear sign that the uterus is preparing to receive a fertilized egg.

Estrogen and progesterone reach their peak around the middle of the luteal phase, while the amount of the corresponding hormones decreases in parallel.

If pregnancy does not occur...

When the egg remains unfertilized, the corpus luteum stops functioning after a while. The level of progesterone and estrogen decreases. Because of this, swelling and necrotic changes in the endometrium occur.

By reducing the level of progesterone, the synthesis of prostaglandins also increases. When the egg is not fertilized, after some time luteolysis begins in the corpus luteum, that is, structural destruction, since it is no longer able to synthesize estradiol and progesterone.

Because of this process, the secretion of lutropin and follitropin is no longer suppressed by anything. The secretion of these hormones increases, which leads to the stimulation of a new follicle. With a decrease in the level of progesterone and estrogen, the synthesis of follicle-stimulating and luteinizing hormones resumes. Thus begins a new cycle in the body of a woman.

Stages of arousal

An important place in the reproductive system is occupied by the stages of excitation of the sexual cycle. There are three of them in total. These are excitation, inhibition and balancing. During this period, changes occur, some of which are easy to notice, while others are elusive even for modern biological devices.

At the stage of sexual arousal in the female body, follicles mature and ovulation occurs. During this period, he is ready to conceive.

During inhibition, signs of sexual arousal appear much weaker. Then comes the stage of balancing, which continues again until a new stage of excitation. During this period, the woman is in the most balanced state. This is influenced by the processes that occur in the body.

Unlike men, women are characterized only by sexual desire, sexual arousal and orgasm, which have their own specifics.

Sexual desire in women is represented by two components - the desire for affection and tenderness (erotic libido) and the desire for sexual intimacy. (sexual libido). Erotic libido, which is not inherent in the nature of men, is inherent in almost all women, because. only about 1% does not feel the need for caresses.

One of the early manifestations of sexual desire in girls is a purely platonic manifestation of interest in the opposite sex. The emergence and development of erotic libido is closely related to the increase in the level of sex hormones that occurs during puberty. This is confirmed by a direct relationship between the onset of menstruation and the occurrence of erotic libido, its delay with delayed puberty, and disappearance after severe hormonal ovarian insufficiency. In healthy women, erotic libido persists throughout life, accompanying sexual libido that appears later. Some women in their development may stop at the erotic stage of libido.

sexual libido, as a rule, it develops in women during regular sexual activity and often only after the onset of orgasm. Unlike the erotic, which depends on the hormonal saturation of the body, the development of sexual libido is determined by individual characteristics, sexual strength, social factors, and to a lesser extent, the concentration and level of sex hormones.

As a rule, sexual desire is more developed in cheerful and sociable women than in reserved women. It is believed that women's libido reaches its maximum around the age of 30, remaining at a stable level until the age of 55, and only then gradually decreases. A natural decrease in sexual desire is observed after 60 years, and therefore its increase at this age is almost always regarded as a pathological phenomenon. A high level of libido is maintained much longer in multiparous women. However, people who have undergone pathological childbirth may experience an earlier decrease in libido. The same can be true for women who have painful periods.

Unlike men, most women have fluctuations in the strength of sexual desire. So, during the period of ovulation, i.e. the release of a mature egg from the ovary, relatively few women reach the maximum libido, although this is the most favorable time for conception. Before or immediately after menstruation, many women experience an increase in sexual desire. There are women who show a desire for sexual intimacy only on certain days of the menstrual cycle. A temporary decrease in libido occurs during illness, after mental and physical overwork, negative emotions.

No clear patterns in the change in the level of sexual behavior of women have been established. It is very individual and rather depends on her mental state.

Some women may experience orgasm. During orgasm, excitement covers the internal organs and especially intensely the central nervous system. At this point, the heart rate can reach 180 beats per minute, the maximum blood pressure rises by 30-100 mm Hg. Art., respiratory rate - up to 40 breaths per minute.

At the moment of orgasm, voluntary control over the skeletal muscles largely disappears. There are involuntary, almost convulsive contractions of the abdominal, intercostal and facial muscles. General reactions of the internal organs and especially intense excitation of the central nervous system together lead to an increase in sexual sensations. At the same time, suppression of other types of sensitivity is often observed in women.

In contrast to the male peaked orgasm, the female orgasm proceeds in most cases in waves. There may be from 5 to 12 waves of orgastic sensations, and with each wave the intensity of pleasure increases. However, there are women with a single short peaked orgasm, which is still longer than that of men. In rare cases, there is a so-called protracted, undulating orgasm, lasting up to 1-3 or even 4 hours. There are also so-called multi-orgasmic women who are able to experience several orgasms during one sexual intercourse, and they experience each next one with greater intensity.

A woman's ability to orgasm to a certain extent depends on the duration of sexual life and sexual experience. While in men, orgasm is usually observed without any prior practice, then in most women it occurs after a more or less regular sexual life, and often after the first or second birth.

Not every woman and not every sexual intimacy is equally satisfying. So, some women can feel a sense of satisfaction without an orgasm. This does not cause them discomfort, because sexual intimacy is for them a symbol and physical expression of love. At the same time, there are women for whom the lack of a regular orgasm causes dissatisfaction and depression.

It is important that in a woman the psychological, conditioned reflex component of sexual desire not only affects the shades of sexual intercourse, as is most often the case with a man, but also plays a dominant role. A woman should see in a man, if not the embodiment of her ideal, then, in any case, a close, dear, respected person.

SEX CYCLE. PREGNANCY

sexual cycle

With the onset of puberty, periodic changes occur in the genital organs of the female human body and other mammals, called sex_cycle. Its regulation is carried out by the endocrine system. During each cycle, the maturation of one, and sometimes several, follicles containing maturing eggs occurs. The exit from the follicle of a mature, capable of fertilizing the egg is called ovulation. In parallel with the maturation of the follicle during the cycle, changes occur in the mucous membrane of the genital organs. Reaching a certain maximum level, these changes again undergo reverse development.

With all the diversity, the sexual cycle consists of several periods: pre-ovulation, ovulation, post-ovulation and rest period.

AT preovulatory period there is usually an increase in one of the follicles, while the epithelium of the uterus grows at the same time. Preovulatory changes occur due to an increase in the secretion of follicle-stimulating hormone by the adenohypophysis, which activates the intrasecretory function of the ovaries, resulting in increased estrogen production (Fig. 11). Under the influence of estrogens, the mucous membrane of the uterus and its glands grow, and contractions of the muscular layer of the uterus increase. Gradually increasing production of FSH accelerates the final maturation of the most mature of the follicles.

Rice. 11. Changes in the ovary and uterine mucosa during a normal menstrual cycle and a cycle that ended in pregnancy (scheme):

1 - the level of estrogen in the blood; 2 - the level of progesterone in the blood; 3 - follicle and corpus luteum during a normal menstrual cycle; 3a - exit from the follicle of the egg, which, remaining unfertilized, dies; 3b - development and then degeneration of the corpus luteum; 4 - follicle and corpus luteum during a cycle ending in pregnancy; 4a - exit from the follicle of the egg, which was then fertilized and embedded in the uterine mucosa; 4b - progressive development and preservation of the corpus luteum; 5 - changes in the mucous membrane of the uterus. The numbers below are the days of the menstrual cycle.

AT ovulation period ovulation occurs, i.e. rupture of the follicle and the exit from it of a mature, capable of fertilizing the egg. The biological reliability of the reproduction of the species in humans is provided by a huge number of eggs, reaching 300,000 at the prepubertal age. However, in each ovulation period, out of 10-15 simultaneously growing follicles, only one fully matures and ovulates.

During ovulation, blood flow to the fallopian tubes (oviducts) increases, there is tension in their smooth muscle fibers, and

movement of cilia of epithelial cells lining the inside of the uterine rough. The ventral end of the fallopian tube opens and during ovulation can be in close contact with the ovary. This usually contributes after the rupture of the follicle to the entry of a mature egg and follicular fluid into the fallopian tube. Subsequent alternating contractions of the muscle fibers of the fallopian tube advance the mature egg towards the uterus. The passage of the egg through the tube to the uterus is about 3 days for a woman.

As the moment of ovulation approaches, and especially during the period of ovulation, the functions of the genital organs and the body as a whole are restructured. These changes occur under the influence of estrogens formed in the follicles. Changes in the hormonal function of the ovaries are reflected in basal temperature body (measured in the rectum). As a rule, before ovulation, the basal temperature fluctuates between 36.1-36.8°, and on the 1st or 2nd day after ovulation, it jumps up by 0.6-0.8°C, actually remaining at this level. before the onset of menstruation. To determine the period of ovulation, basal temperature is measured daily, in the morning after sleep at the same time, with the same medical thermometer.

The ovum released from the follicle can be fertilized. Fertilization occurs only if sexual intercourse occurs shortly before or shortly after ovulation. If fertilization does not occur, then the next period of the sexual cycle begins - post-ovulation. It occurs when a corpus luteum develops from the walls of an empty follicle in place of a burst follicle after ovulation. About 2 days after ovulation, the unfertilized egg dies.

The corpus luteum is a temporary endocrine gland that produces the hormone progesterone. Under the influence of progesterone, the release of follicle-stimulating and luteinizing hormones by the adenohypophysis decreases. A decrease in the concentration of LH in the blood leads to the fact that after a few days the corpus luteum begins to dissolve and the cavity of the former follicle is filled with connective tissue. At the same time, the production of progesterone decreases and then stops (Fig. 11). The decrease in FST leads to a decrease in the formation of estrogens in the ovaries. An unfertilized egg remains in the woman's genital tract for several days and then dies.

A decrease in the concentration of progesterone and estrogen in the blood causes change in blood circulation in the vessels of the uterine mucosa. Stagnation of blood in the vessels and slowing of blood flow leads to an increase in pressure inside the vessels, their walls are torn and bleeding begins. At the same time, tonic contractions of the uterine muscles occur,

leading to rejection of the uterine mucosa. The removal of parts of the mucous membrane from the body along with the blood is called menstruation. The average duration of menstruation is 2-3 days.

Following the post-ovulation period, the period of inter-ovulation begins. this rest. At this time, the follicles are relatively small, the uterine lining is thin and contains fewer blood capillaries. The rest period passes into the pre-ovulation period of the next sexual cycle. New follicles begin to develop in the ovaries and estrogen secretion increases again.

In women, the sexual cycle is called the menstrual cycle. It is considered to be from the first day of the onset of menstruation to the first day of the next menstruation. The duration of the menstrual cycle in women 18-45 years old, i.e. childbearing age, it also happens in the range from 21 to 35 days. The best is the menstrual cycle, lasting 28 days, because. at the same time, the most constant periodicity of cyclic changes is observed. Menstrual cycles begin at puberty, i.e. at 11-16 years old, and stop at 45-50 years old.

Changes in the concentration of gonadotropic and sex hormones in the blood plasma of a woman during the menstrual cycle can have a noticeable effect on her behavior. In some women, before menstruation, the excitability of the nervous system increases, irascibility and irritability increase.

Pregnancy

For pregnancy to occur, a mature egg, leaving the ovarian follicle and ending up in the abdominal cavity, must enter the fallopian tube, meet the sperm there, be fertilized, begin to divide and simultaneously move into the uterus, in order to then attach and penetrate into its mucous membrane. Only under these conditions is an opportunity created for the development of a new organism.

fertilization called the fusion of a sperm with an egg, leading to the formation of a zygote, which divides, grows, develops and gives rise to a new organism. During fertilization, the sperm nucleus merges with the egg nucleus, which leads to the unification of paternal and maternal genes and the restoration of the diploid set of chromosomes.

With a correct 28-day menstrual cycle, a mature egg leaves the ovary 12-14 days after the first day of the previous menstruation. Within about 3 days, the egg moves along the fallopian tube into the uterus, and along this path, it can be fertilized when it meets sperm. The best option is when the fertilization of the egg occurred in the upper sections of the fallopian tubes.

In some cases, spermatozoa pass the entire length of the fallopian tube and fertilize the egg immediately after ovulation, even before it enters the fallopian tube. In such cases, attachment of the embryo may occur to the ovary or abdominal wall, leading to the development of an ectopic pregnancy. An ectopic pregnancy is very dangerous for a woman, because. She definitely needs emergency surgery.

The lifespan of the ovum released from the follicle and the duration of the functioning of spermatozoa in the female genital tract are determined in the menstrual cycle period value, during which fertilization is possible. With a 28-day cycle and ovulation on the 14th day after the first day of the previous menstruation, fertilization can occur from the 12th to the 16th day. However, one should take into account possible fluctuations in the timing of ovulation, which can be caused by physical and mental stress, fluctuations in ambient temperature, moving to another climatic zone, etc. Usually, the shift in the ovulation period does not exceed 3 days closer to the beginning or to the end of the menstrual cycle. Therefore, fertilization can occur from the 9th day to the 19th day of the menstrual cycle. This period has a different duration with a different length of the menstrual cycle or with irregular menstruation.

After fertilization and formation on the second day of the embryo over the next three days, it must necessarily move through the fallopian tube into the uterus and gain a foothold in its mucous membrane. The movement of the embryo is provided by wave-like contractions of the fallopian tube and the movements of the cilia of the epithelium of its mucous membrane. If the movement of the embryo slows down due to the narrowness or poor patency of the fallopian tube, then it will remain in it. This will lead to the death of the embryo or the onset of a tubal pregnancy, in which the embryo dies at a later date. A tubal pregnancy requires urgent surgery.

If the embryo enters the uterus too quickly, as well as too late, it will not be able to penetrate and gain a foothold in the uterine mucosa and pregnancy will not occur. In some cases, even the timely entry of the embryo into the uterus does not guarantee the normal course of pregnancy. For example, if the embryo attaches itself to scars formed in the area of ​​the uterine mucosa after abortions or to a node that has arisen after inflammatory diseases of the uterus, then the conditions for its nutrition and further development will be extremely unfavorable. In such cases, there is often a threat of spontaneous miscarriage.

After the embryo has successfully penetrated into the mucous membrane of the uterine cavity, which has loosened by this time, the cells of the outer layer of the embryo begin to produce a specific hormone. This hormone

stimulates the production of other hormones that contribute to the preservation and development of pregnancy. If a woman does not have another menstruation, then we can hope that the introduction of the embryo into the uterine mucosa has occurred and the pregnancy develops. Doctors can see the fetus as early as 4 weeks of age using an ultrasound machine. Even earlier, pregnancy can be detected as a result of a biochemical study.

From the 7th week of pregnancy, the so-called baby place begins to form, or placenta. Doctors consider the period of 7 weeks to be the most critical period of pregnancy, because. it is at this time that its premature interruption most often occurs. Reason for interruption hormonal imbalance in a woman's body. The placenta secretes a complex complex of hormones and other biologically active substances into the mother's body, among which the hormone progesterone is of particular importance, which contributes to the preservation and development of pregnancy. Before the formation of the placenta, progesterone is produced only in the corpus luteum, which formed at the site of the burst follicle after the release of the egg from it. Hormonal imbalance can occur if it is by the 7th week that the function of the corpus luteum begins to fade significantly, and the formation of the placenta, which compensates for the resulting progesterone deficiency, is late. If left untreated, this hormonal imbalance can cause a miscarriage.

With normal development, a woman's pregnancy lasts an average of 280 days, counting from the first day of the last menstruation. Pregnancy is divided into three periods - trimester, each of which has its own characteristics.

First trimester(1-3 months) is the period of maximum vulnerability. At this time, in addition to the introduction of the embryo into the uterine mucosa, complex processes of laying the internal organs of the fetus occur. The first trimester is especially large danger of alcohol for the fetus. Alcohol disrupts the formation of internal organs, causing various deformities. The brain suffers the most. Brain damage manifests itself after the birth of a child in a lag in mental development up to progressive dementia. Every third child of drinking mothers has a congenital heart disease, deformities of the hands and feet, malformations of the kidneys, urinary tract of the genital organs are quite common.

Alcohol also complicates the course of pregnancy. Pregnant women who drink alcohol are much more likely to experience spontaneous miscarriages, premature births of premature and immature fetuses. They have toxicosis of pregnancy and labor is complicated.

On the Smoking is also strictly prohibited. For the fetus, not only smoking of the mother is dangerous, but also her stay in a smoky room, because. carbon monoxide, nicotine and other toxic substances contained in tobacco smoke impair the supply of oxygen to the fetus and have a toxic effect on it.

The placenta, which serves as a barrier between the organs of the mother and fetus, is unable to protect it from many chemicals, drugs and viruses. Therefore, pregnant women should not work in chemically hazardous industries. They should take medicine carefully and only as prescribed by a doctor, and should also avoid contact with patients with influenza and other viral infections.

Second trimester(4 - 6 months of pregnancy) in healthy women proceeds mostly calmly. The period of physical and psychological adaptation gradually passes, the reactions of the nervous system are balanced, salivation, nausea disappear, appetite improves. The body of a woman adapts to a new state.

With an uncomplicated pregnancy, as in the first trimester, daily morning exercises are very useful, excluding jumps, sudden movements and turns. In the second trimester, a complex of special gymnastics is recommended, which is selected by the doctor of the antenatal clinic. Walks in the fresh air are very useful, helping to improve the supply of oxygen to the fetus. You can walk up to two hours in a row and be sure to 30 minutes before bedtime. Very useful are air baths and daily showers, which improve skin respiration. The nutrition of a pregnant woman should be complete with an increase in the amount of protein, vitamins and mineral salts.

Starting from the 5th month, a pregnant woman begins to increase blood pressure, so it is important to monitor its dynamics. The second trimester is very important for women who have had previous pregnancies interrupted during this period. They need a sparing regime, and in some cases - treatment in a hospital.

third trimester pregnancy starts from the 28th week. In this trimester, the woman's body is under great stress. The intensive growth of the fetus places increasing demands on liver and kidneys mother. Work is often difficult hearts, because it begins to be crowded by the dome of the diaphragm, lifted by the fetus. It also complicates the work of the digestive system. Sometimes the contents of the stomach are thrown into the esophagus and there is a feeling of heartburn, a bitter taste in the mouth. With an increased load, the venous system functions, in which blood pressure rises.

At this time, it becomes even more important to maintain the correct regimen. First of all, it is necessary to make adjustments to

diet and completely abandon spicy, salty foods, spices and smoked foods. These products complicate the work of the kidneys, contribute to fluid retention in the body and can provoke the development of the so-called late toxicosis of pregnancy, which is extremely dangerous for the health of the mother and child.

In the third trimester, the first courses should be only vegetarian. From fats, butter and vegetable oil are recommended, vegetables - raw, boiled and stewed, bread - preferably from wholemeal flour. It is very important to follow the increase body weight, which should not exceed 500 g per week, and for persons who are inclined to be overweight - 300 g per week. The normal course of pregnancy in this period is evidenced by normal blood pressure, the absence of edema and normal urine tests. However, if it becomes difficult to remove the ring from the finger or the shoes become tight, you should consult a doctor.

In the third trimester, it is necessary to observe the correct daily routine. It is rational, at the same time to eat, be sure to walk in the fresh air. The duration of walking should be increased, but you should walk more slowly and sit down more often. Women who, on the recommendation of a doctor, were engaged in special gymnastics can continue it. However, the pace of the exercises should be slowed down and some of them, and after the 36th week - almost everything, should be performed only while sitting and lying down.

In order for a woman to rest and get stronger before childbirth, she is given prenatal leave. At this time, she can do ordinary, but not time-consuming household chores. Work with pesticides and household chemicals is strictly prohibited. A normal or even complicated pregnancy, with proper medical supervision, usually ends with the birth of a healthy, viable child.

LITERATURE

1. General course of human and animal physiology. - Ed. HELL. Nozdrachev. - M .: Higher School, 1991.

2. Human physiology. T. 4. - Ed. R. Schmidt and G. Thevs. – M.: Mir, 1986.

3. Human physiology. - Ed. G.I. Kositsky. – M.: Medicine, 1985.

4. Leont'eva N.N., Marinova K.V. Anatomy and physiology of the child's body. – M.: Enlightenment, 1986.

5. Drzhevetskaya I.A. Endocrine system of a growing organism. – M.:
High School, 1987.

6. Shepherd G. Neurobiology. T. 2. - M .: Mir, 1987.

7. Bloom F., Leyzerson L., Hofstadter L. Brain, mind and behavior. -
M.: Mir, 1988.

8. Danilova N.N. Psychophysiology. – M.: Aspect Press, 2000.

9. Shostak V.I., Lytaev S.A. Physiology of mental activity
person. - St. Petersburg: Dean, 1999.