Menstrual function

The menstrual function is one of the specific functions of the female body, which also include reproductive, secretory, and sexual functions.

Menstrual dysfunction occurs in 30-40% of women. Their consequences lead not only to a woman's health and ability to work, a violation of her comfort in life, but also cause significant social and economic damage. Since the specific functions of a woman are determined by hormonal processes in the body, the study of the patterns of menstrual function and its disorders, diagnostic methods and treatment of the latter are the basis of gynecological endocrinology.

Menstrual function is a clinical manifestation of cyclic processes of monthly preparation of the female body for pregnancy. It includes a set of endocrine-metabolic (changes in body weight, muscle strength, functioning of the most important organs and systems), vascular (vascular tone, pulse rate and blood pressure, fluid retention), mental changes (irritability, memory loss, insomnia) in the female body during the menstrual cycle. This is a complex process that determines the possibility of conception, proper formation of the fetus, and carrying a pregnancy.

The external manifestation of the menstrual function is menstruation (monthly, periods - lat.) - regularly appearing bloody discharge from the genital tract, caused by the rejection of the functional layer of the endometrium. The period from their beginning to the beginning of the next menstruation is called the menstrual cycle.

The totality of hormonal changes in the system of regulation of sexual (reproductive) function during the cycle is called the hormonal cycle. It should be emphasized that in case of menstrual dysfunction, the hormonal and menstrual cycles may not coincide in duration, which should be taken into account when examining patients.

In her development, a woman goes through several periods during which the menstrual function is established, flourishes and fades:

• Perinatal - including intrauterine and 168 hours after birth. During this period, the laying and formation of the female reproductive system occurs, determined by the specific karyotype 46XX. By the time of birth, the regulation system of the reproductive system, the hormones-regulators acting in it and the target organs of the reproductive system are fully formed.
• Prepubertal (newborn and childhood) - lasts up to 10 years (before the onset of puberty). During this period, the slow maturation of the system regulating specific functions of the female body, including the menstrual system, continues.
• Puberty (sexual maturation) - takes place from 10 to 16-18 years. It is characterized by the development and maturation of the body, which occurs under the influence of increased hormone production. An important moment is the first menstruation - menarche, indicating that girls have entered a qualitatively new stage of sexual development and the inclusion of the sexual function regulation system. However, the onset of menarche does not yet mean the onset of sexual maturity, since for 1-2 years menstruation is still of an anovulatory nature, and it is more correct to call them menstrual-like discharge.

Factors that determine the development of menstrual function include: socio-economic and material-domestic living conditions, diet, severe or long-term somatic diseases, infections, intoxications, and sports.

• Reproductive - the main, biologically determined period of flourishing of specific functions of the female body. It lasts about 30 years - from 16-18 to 45-49 years.
• Climacteric - a period of gradual fading of specific functions. Currently, due to the increase in life expectancy, it takes up to a third of it - from 46 to 65 years.
• Senile (old age) is an age period starting at 65 years.

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Regulation of specific functions of the female body

Neurohormonal (neurohumoral) regulation of specific functions of the female body (including menstrual) is carried out by a feedback mechanism between the central (cerebral cortex, hypothalamus, pituitary gland) and peripheral (ovaries) links of the regulation system and target organs (uterus and appendages, vagina, mammary glands) of the reproductive system. The main hormone - regulator of the feedback system is estradiol E2), produced by the ovaries.

The transition of a nerve impulse in the regulatory system into a hormonal factor is carried out at the level of the hypothalamus. There are 2 groups of hypothalamic hormones: liberins (releasing hormones), stimulating the synthesis and release of tropic hormones of the corresponding peripheral glands from the pituitary cells, and statins (inhibins), inhibiting the production of adequate tropic hormones. For the reproductive system, 2 liberins are of primary importance: luliberin (LH-releasing hormone, LH-RH, Gn-RH), stimulating the simultaneous production of LH and FSH by gonadotrophs of the anterior pituitary gland, and thyroliberin, which is a physiological stimulator of not only TSH, but also the third gonadotropic hormone - prolactin. Secretion of LH-RH by the hypothalamic nuclei occurs in a pulsating mode with a frequency of release into the bloodstream of approximately 1 time per hour (circhoral rhythm of secretion). The role of hypothalamic statins is performed by such biogenic amines as dopamine and serotonin. According to modern concepts, dopamine is a physiological hormone-inhibitor of prolactin secretion. Its deficiency leads to the rupture of synaptic connections of hypothalamic neurons and an increase in the level of prolactin in the blood serum. Excess prolactin leads to the formation of such a common pathology as hyperprolactinemic ovarian insufficiency (up to 30% of regulatory disorders of menstrual function).

Gonadotropic hormones produced by cells of the anterior pituitary gland (adenohypophysis) include luteinizing hormone (LH), follicle-stimulating hormone (FSH) and prolactin (PRL).

Under the influence of gonadotropic hormones of the pituitary gland, a sequential synthesis of sex steroid hormones occurs in the ovaries: androgens (testosterone and androstenedione) are formed from cholesterol, and from them, in turn, estrogens (estrone-E1, estradiol-E2 and estriol-E3) and gestagens (progesterone and 17beta-hydroxyirogesterone) are formed through a series of biochemical transformations. The role of the regulator of the feedback mechanism in the reproductive system is played by estradiol, the receptors of which are present in all its sections.

During most of the cycle, the secretion of LH and FSH is relatively constant (basal or tonic secretion). Under the influence of the latter, the growth of estrogen production (secreted by the granulosa of the maturing follicle) during the 1st phase of the cycle ensures proliferative processes in the uterine endometrium and vaginal mucosa. The threshold level of estrogens via the feedback mechanism stimulates the preovulatory surge of LH-RH and gonadotropins, which ensure the ovulation mechanism (release of the mature egg from the dominant follicle) in the middle of the cycle (14-16th day of the cycle). The growth of progesterone production at the end of the 1st phase of the menstrual cycle potentiates the effect of estrogens in the feedback mechanism. The corpus luteum formed in place of the follicle produces gestagens and estrogens, which support secretory transformations in the endometrium during the 2nd phase of the cycle. The corpus luteum blossoming phase (days 19-21) with maximum production of ovarian hormones reflects the readiness of the endometrium for implantation of the fertilized egg. In the absence of pregnancy, regression (luteolysis) of the corpus luteum occurs. A drop in the production of its hormones causes a second, smaller in amplitude, release of gonadotropins at the end of the 2nd phase of the cycle, which includes the mechanism of menstruation. The third gonadotropic hormone - prolactin not only participates in the formation of the preovulatory peak, but also supports, when pregnancy occurs, the processes of implantation of the fertilized egg into the mucous membrane of the uterus. This is reflected in the growth of the level of its production within the basal secretion at the end of the 2nd phase (days 25-27 of the cycle).