The functioning of the female reproductive system is provided by the existence of a single regulatory system, which consists of multiple layers of regulation. This complex neuroendocrine system includes central and peripheral parts, as well as a certain number of intermediate links. All levels of the system (there are five) are subject to a strict hierarchy and work on the principle of the relationship (direct and inverse relationship). The regulation of the menstrual cycle is influenced by various factors, which can lead to disturbances at any level of the system.

The regulation loop at the top or central level

The very first level of the regulatory system, which was called the higher is considered the level of the central structures of the brain .  It cortex and departments that make up extrahypothalamic structure (the structure of the limbic system, gippokapma) .  At this level, the brain takes a balanced synthesis and subsequent metabolic transformation of substances, "transmitter" or neurotransmitters, which provides for all the physiological processes in the reproductive system (menstrual function, ovulation, and others) .  By neurotransmitters include substance - norepinephrine, dopamine, serotonin, melatonin .  On the first level of the neuroendocrine system may develop disorders related to the perception of the nervous system outside influences .  This will depend on further operation of the whole of the reproductive system in general .  Well-known cases, when a woman stops menstruating after experiencing stress How to beat stress? Create an oasis For example, after bereavement. Another example is the advent of the "false pregnancy" a woman with a strong desire to have children. In this case, there is no obvious external influence, but there is a psychological imbalance that is the cause of the delay menstruation.

To the central area is the level of the hypothalamus, which is the second level. In this zone are core having secretory activity. They produce hormones (are called gonadotropin-releasing hormone), which have a stimulating or blocking action. The main hormones are folliberin and lyuliberin. Their secretion is programmed at the genetic level, and takes place in a pulsed (or tsirhoralnom) mode. This mode means the peak hormone secretory activity for a few minutes, which then gives way to a decline in activity that lasts for a few hours, to a maximum of three hours. The existing feedback mechanism leads to the development of frequency and amplitude secretion releasing hormones from the level of sex hormones, particularly oestradiol Estradiol, the most important hormone   (the most active fraction of estrogen). Also, the effect on the activity of secretion have allocated nadgipotalamicheskimi structures neurotransmitters.

Another third level of regulation is the area of ​​the anterior pituitary gland, in which the basic production of gonadotropin-releasing hormone:

• FSH or follicle stimulating hormone, follitropin. Its main action is to ensure the growth and maturation of the follicle
• LH, or luteinizing hormone, lutropin. Together with the FSH hormone that promotes the process of ovulation Ovulation - How to determine as accurately as possible?   and further the formation of the corpus luteum
• Prolactin. The biological role of prolactin is to stimulate the growth of breast and lactation in ensuring
• Adrenocorticotropic hormone or ACTH
• Growth hormone or growth hormone
• TSH, or thyroid stimulating hormone

If each of these hormones secreted in the balanced mode, it will provide the normal activity of the whole of the reproductive system.

What happens during the cycle of the peripheral endocrine organs

The main role in the regulation at the level of the peripheral parts of the system is given the ovaries and other organs involved in the functioning of the reproductive system, supporting her .  From the moment of birth to the moment of extinction of the sexual activity of the ovaries is a gradual maturation of the follicular unit, followed by the onset of ovulation or pregnancy, corpus luteum formation and production of sex hormones .  The process of their development occurs cyclically, depending on whether a phase of the cycle, the follicular or luteal .  On the functioning of the organism sex steroids affect isolation and integrated with other hormones .  The important endocrine organs are still thyroid gland, adrenal glands, which have a direct effect on the functional activity of the reproductive system .  Together, they make up the fourth level of the peripheral regulation .

Under the last fifth level regulating system is the so-called target organs. These include internal and external organs of the reproductive system (uterus, tubes, vagina), mammary gland. These bodies are sensitive to fluctuations in the levels of steroid hormones that epitomized in the changes in the endometrium, or menstruation. During menstruation is rejected or the surface of the basal layer of the endometrium, which occurs due to the hormonal changes of the body. The main effect in the first phase have hormone estrogen, and the second - progesterone Progesterone - norm and pathology   together with estrogens. The process of successive changes in the uterine mucosa includes the step of proliferation, secretion and directly menstruation. What matters is not only the cyclical fluctuations in hormone levels, as well as the status of specific receptors in the tissues of these sexual hormones.

Reproductive system operates in a cyclic mode, and is determined by two main regulatory principles - the presence among all levels of forward and reverse links.

Marina Solovyov

Physiological amenorrhea, ie complete absence of menstruation in a woman for more than six months not uncommon. The most common physiological amenorrhea occurs during pregnancy and nursing Breastfeeding - a personal choice   feeding. Physiological amenorrhea is also in children, adolescents and older women.

Physiological amenorrhea during pregnancy

Physiological amenorrhea (ie a complete lack of menstruation) during pregnancy is associated with the fact that the mucous membrane of the uterus is not rejected, as it occurs during menstruation. This happens because hormonal support at the end of the next menstrual cycle after conception occurred, not only does not decrease (this is the reason for the rejection of the mucosa and the onset of menstruation), but, on the contrary, increased.

Once the embryo is embedded in the wall of the uterus, its shell start to allocate the pregnancy hormone - human chorionic gonadotropin (hCG). HCG stimulates the secretion of the female sex hormone progesterone Progesterone - norm and pathology Whose main task is to suppress the contraction of smooth muscles of the uterus, which could lead to rejection of the embryo with the mucous membrane of the uterus.

Therefore, during pregnancy, menstruation does not happen - the rejection of the mucous membrane of the uterus during this period always leads to abortion.

Physiological amenorrhea during breastfeeding

After giving birth, the pituitary gland starts secreting the hormone prolactin, which inhibits the secretion of pituitary gonadotropins (TG) - follicle-stimulating and luteinizing hormone (FSH and LH). The main function of FSH is the hormone support follicle maturation, as well as this hormonal support is insufficient follicle matures, the egg is not released from the ovary (ie, no ovulation), in connection with which the fertilization impossible.

But to physiological amenorrhea The absence of menstruation (amenorrhea) - ambiguous symptom   could become a reliable protection against unwanted pregnancy, breast-feeding should take place regularly. Mixed feeding (when, after applying to finish feeding the baby breast milk formula) is not sufficient protection, since it is produced is not enough. After the introduction of the first foods Introduce solid foods - how not to be mistaken with a choice of products?   (5-6 months) protection against unplanned pregnancy is also reduced.

Physiological amenorrhea in childhood and adolescence

Physiologically amenorrhea is typical for children and adolescents. It is connected with the fact that inherent in utero ovarian egg girls are not ready yet to mature.

At the age of 11-12 years under the influence of female hormones estrogen increase the girl's body weight, formed the primary sexual characteristics of female type. When the weight of her body reaches a certain level, the cerebral cortex sends a signal to the hypothalamus, which is involved in the work by secreting hormones that stimulate the secretion of pituitary gonadotropins (TG) - FSH and LH. Under the influence of FSH egg matures in the ovary, and under the influence of LH, it breaks the follicles, which mature and released from the ovary. Stopping hormonal support leads to the first menstrual period - menarche.

Regular menstruation sometimes installed at once - it depends on what at first neurohormonal system malfunctions. But in most cases, regular menstrual cycles is set for about a year.

Physiological amenorrhea in the elderly

Physiological amenorrhea in old age (menopause) occurs on average at age 50. This reduces the function of the ovaries, they begin to produce enough female hormones. This increases the stimulatory effect on the pituitary ovaries as increased secretion of gonadotropins (TG) - FSH and LH.

The lack of female sex hormones estrogen leads to the fact that more and more menstrual cycles become irregular (no ovulation), that is during the menstrual cycle does not occur yield mature egg from the ovary. Menstrual cycles become irregular, often very long, but sometimes, on the contrary, shorter. But gradually suppressed and the function of the pituitary gland, which leads to menopause. The lack of female sex hormones leads to a complete restructuring of the metabolism of women. Particularly affected mineral metabolism: there is leaching of calcium from the bone, which leads to its increased fragility and propensity to fractures - osteoporosis.

Physiological amenorrhea - a natural state of women who do not require treatment.

Galina Romanenko