Woman's menstrual cycle - is a tool that allows it to conceive, carry and give birth to a child. The first menstruation begins in 11-16 years, the last ends at the age of about 50 years. This period in a woman's life is called the genital or fertility.
The menstrual cycle of women as a physiological process
Woman's menstrual cycle is the cyclical changes that occur on a monthly basis in the central nervous system, ovaries, genitals and breasts of women. All of these processes are closely linked and have a significant impact on the work of all other organs and body systems. The slightest violation of the menstrual cycle has always reflected the state of the nervous and cardiovascular systems, and through them to all the other organs.
The first menstruation, the girl called menarche. In women southern people menarche occurs earlier than in the north. The length of the menstrual cycle is measured from the first day of the ensuing menstruation to the first day of the next menstruation. The average duration of the menstrual cycle - 28 days, but the norm is its duration from 21 to 35 days.
The normal menstrual cycle is divided into two phases with the predominance of the activity of female sex hormones estrogen or progesterone. Isolation of female sex hormones is influenced by the cerebral cortex and subcortical structures responsible for the activity of the endocrine glands - the pituitary gland and the hypothalamus.
The first phase of the menstrual cycle - estrogen
During this phase, there is a maturing egg in the ovary within 13-14 days. In the ovaries of a newborn girl, there are hundreds of thousands of so-called primordial follicles, which consist of egg, surrounded by a single layer of follicular epithelium. Under the influence of hormones begins with the onset of menarche, maturation of the primordial follicle. During the menstrual cycle, only one follicle reaches full maturity. Matured oocyte follicle bursts and released from the ovary, first entering the peritoneal cavity and then into the fallopian tube. The moment of release of the egg from the ovary is called ovulation
Ovulation - How to determine as accurately as possible?
, It usually occurs on day 14 (at 28 - day cycle).
The process of follicle maturation occur under the influence of ovarian hormones estrogen (primarily estradiol) and follicle-stimulating hormone (FSH), the pituitary gland (the main endocrine gland located in the brain).
Between the pituitary and ovarian hormones has an inverse relationship: if the estrogen is released much, the amount of FSH is reduced and vice versa. Number of pituitary hormones is in the same depending on the hormone, which is secreted by the hypothalamus - a brain region responsible for all endocrine activity of the human body.
At the same time with the maturation of the egg cyclical changes occur in the lining of the uterus - in her glands, blood vessels and proper in the mucosa - the stroma. First, the mucous membrane of the uterus is torn away and menstruation occurs, then the mucous membrane recovers and grows.
There are changes in the mammary glands. Under the influence of estrogens increase in length mammary ducts, the mammary glands swell.
The second phase of the menstrual cycle - progesterone
The second phase of the menstrual cycle begins after the release of the mature egg from the ovary. The amount allocated to the ovary estrogen decreases sharply, and the place of the ruptured follicle forms a temporary endocrine gland - the corpus luteum, which starts to produce progesterone
Progesterone - norm and pathology
If the task of the first phase of the menstrual cycle was to create conditions for oocyte maturation and prepare the uterus for the introduction of a fertilized egg in it, the task of the second phase of the menstrual cycle is to keep a fertilized egg in the uterus.
Therefore, under the influence of progesterone dramatically reduced motor activity of smooth muscles of the uterus (which prevents miscarriage). Isolation progesterone stimulates the luteinizing hormone (LH) of the pituitary gland. At this time, the uterus begins secretory phase - gland epithelium lining of the uterus starts to develop a secret that prepares the uterus to receive the embryo.
If fertilization occurs, the first 10 days of the fertilized egg moves through the fallopian tube to the entrance to the uterus. After entering the uterus fertilized egg (embryo) is introduced into the prepared mucous membrane of the uterus and begins to grow into it more deeply, connecting with the mother numerous blood vessels (the first 10 days the embryo was not related to the mother's body, he ate at their own stocks ).
If fertilization does not occur, the corpus luteum atrophies and becomes a barely noticeable white scar - white body. Without progesterone the mucous membrane begins to be torn away, and the muscles of the uterus - to decline, throwing the contents - begins a new menstrual cycle.
Every woman should know their menstrual cycle - its duration and other features that, in the case of menstrual disorders
Menstrual cycle and its characteristics
time to see a doctor.
- the phase of the menstrual cycle