The menstrual cycle in a woman's body plays a huge role. And like all the processes occurring in the body, the menstrual cycle has its own regulation. The system of regulation is very complex and is built in the form of stairs, in a hierarchical type. All underlying structure overlying subject, but in turn, the signals from the underlying structures regulate the overlying.
Menstrual cycle
The menstrual cycle - a cyclical changes in the female body, aimed at the preparation and implementation of conception. Literally translated from the Latin, the menstrual cycle is called the lunar cycle. The average duration of 28 days, but can range from 21 to 35 days. The countdown of the menstrual cycle begins on the first day of menstruation to the first day of the next. The duration of the menstrual cycle is individual for each woman and depends on the physiological characteristics.
Levels of regulation of the menstrual cycle
The regulation of the menstrual cycle are five levels:
This level includes extrahypothalamic cerebral structures - the cerebral cortex. These structures perceive pulses coming from the external environment with their further transmission to the hypothalamus. The flow of information coming from the outside and cause emotions
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Behavior and mental activity affects the condition of the reproductive system. An example would be a violation of ovulation with stress, heavy or hazardous conditions, climate change.
The second level of regulation of the menstrual cycle include the hypothalamus, which in turn controls the operation of the pituitary. The hypothalamus is presented in the form of clusters of nerve cells synthesizing specific hormones (corticotropin releasing hormone). Lyuliberin releasing hormone and its analogs affect the pituitary gland, and cause it to produce steroids - follicle-stimulating hormone (FSH) and luteinizing (LH) hormones.
The third level of regulation - is directly the pituitary gland. It synthesizes follicle stimulating and luteinizing hormone, and prolactin governing the functioning of the ovary and breast. Iron target for FSH and LH hormones is the ovary. They stimulate the growth and maturation of the follicle. Luteinizing hormone promotes the formation of androgens and progesterone synthesis in cells ovulirovshego follicle (ie, after maturation and release of the egg). Prolactin is responsible for breast growth and lactation. Furthermore, prolactin possesses antihypertensive properties.
The fourth level of regulation - is the ovaries. Ovaries undergoing complex processes of steroids and follicular development. During ovulation, a mature follicle bursts and the egg comes out of it. Remains of the follicle later transformed into the corpus luteum which produces progesterone
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. There are two types of yellow bodies: the first - menstrual, which regress at 12-14 days of the menstrual cycle
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(formed from a white body which resolves) and the second - the corpus luteum of pregnancy in the case of fertilization (operates the entire pregnancy and reaches a huge size).
By the fifth level of the regulation of the menstrual cycle are the target organs. They are the final destination of the action of sex hormones synthesized by the ovaries. It genital organs (uterus, tubes, vagina) and other (breast, skin, adipose tissue, bone). All these organs contain receptors for sex hormones.
The phases of the menstrual cycle
There are four phases of the menstrual cycle:
Follicular phase begins with the first day of the menstrual cycle. At this time the maturation of the main (dominant) follicle from which subsequently leaves mature egg. In the uterus during this period begins to grow and thicken the endometrium (functional layer), which is prepared to accept a fertilized egg.
By the seventh day is determined by the dominant follicle, which continues to grow and secrete estradiol, while other follicles in this period atreziruyutsya (regress). This phase lasts three days, this is accompanied by the release of luteinizing hormone, which is under the influence of the dominant follicle bursts and the egg leaves mature. That is, ovulation occurs within 24 hours.
Secretory phase - is the period between ovulation
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and the onset of menses. During this period, the corpus luteum is formed which starts to produce progesterone (pregnancy hormone), estradiol and androgens. During the secretory phase endometrial glands mature, proliferate and begin to secrete. If fertilization has occurred, it is implanted in the endometrium is already prepared. If fertilization does not happen, the corpus luteum is reduced (growing back), progesterone levels fall and menstruation begins.
Phase desquamation - a rejection of the functional layer of the endometrium - menstruation.
Anna Sozinova
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- regulation of the menstrual cycle