Woman's menstrual cycle occurs in two phases, which divides the time of ovulation - release egg from the ovary. These two phases and ovulation occurs under the influence of the nervous and endocrine systems of the body are women. Formed menstruation during adolescence and ends at the age of about 50 years.

The menstrual cycle begins on the first day of the next menstrual period and continues until the first day of the next menstruation. On average, it is 28 days, but the norm is and 21 - 35 days.

The first phase of the menstrual cycle

The first phase of the twenty-eight day menstrual cycle lasts 14 - 16 days. During this phase, the ovarian oocyte maturation occurs. At birth, a girl in her ovaries, there are about 400,000 eggs, surrounded by a layer of follicular epithelium, that is enclosed in a bubble. On reaching the age of puberty, under the influence of hormones during each menstrual cycle, one egg matures. In the maturation of the egg in the first phase of the menstrual cycle affect the pituitary follicle-stimulating hormone (FSH) and the female sex hormone estrogen, which produces follicular epithelium. While FSH stimulates the production of estrogen and. In the first phase of the menstrual cycle, estrogen secreted mainly estradiol.

Under the influence of these hormones is not only the maturation of the follicle, but also training of all authorities to pregnancy. In the uterus under the influence of estrogen occurs gradual change in the internal mucosa. First, the mucous membrane of the uterus is removed (step desquamation), which is accompanied by bleeding (menstruation). At the same time immediately begins rebuilding the mucous membrane, which extends the first 5 - 6 days after the onset of menstruation. The mucous membrane increases in volume, it proliferating glands and blood vessels (proliferation stage). The thickness of the functional layer of the uterus mucosa by the end of proliferation stage is 4 - 5 mm.

At the same time in the ovary begins to ripen a new egg. By the middle of the menstrual cycle The menstrual cycle - that occurs in different phases?   follicle maturation and usually finishes this signal enters the central nervous system (CNS). Under the influence of the central nervous system completely hormonal changes. One day before the release of the egg from the ovary decreases the secretion of FSH and LH secretion increases. This change stops the ripening process, the follicle bursts, the egg comes out of it in the abdomen and in the norm immediately falls into the outer opening of the fallopian tube.

Ovulation

The moment of release of the egg from the ovary is called ovulation. The moment of ovulation is very important, since after ovulation the egg lives for a day, and then dies. Conception can or within days after ovulation, or for three days before it as live sperm from one to three days. At other times of the menstrual cycle, conception is impossible, so at conception Conception - as the emerging life   child sexual contact should occur at this time.

The moment of ovulation is also used for natural contraception. If pregnancy is not planned, it is unprotected sex without consequences of pregnancy is possible after two days post ovulation (the extra day - the correction for an error in the date of ovulation).

The second phase of the menstrual cycle

The second phase of the menstrual cycle begins immediately after ovulation. At the site of the ruptured follicle under the influence of pituitary LH image of a temporary endocrine gland - the corpus luteum. The corpus luteum secretes female sexual hormone progesterone, which is under the influence of begin to function gland mucosa of the uterus. Simultaneously progesterone inhibits all muscle contractions of the uterus in order to prevent interruption of pregnancy (with insufficient progesterone uterus can simply discard the embryo from the cavity).

If pregnancy occurs (in the fallopian tube fertilization by sperm), the egg during the week moves toward the uterus and at the end of the week is being introduced in the lining of the uterus. If pregnancy does not occur, the corpus luteum begins to produce less progesterone and by the end of the menstrual cycle, it becomes so small that it is unable to contain the muscular contractions of the uterus. As a result of the lack of hormonal support and active muscle contractions of the uterus inner lining of the uterus is rejected and the next menstruation begins, which also coincides with the first day of the subsequent menstruation.

The menstrual cycle of women - is a thin multi-step mechanism that allows a woman to become a mother. If the menstrual cycle at any stage is broken, it is an obstacle to the birth of the child.

Galina Romanenko

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