Cycles of female organism



Why does a woman experience regular cyclic changes? Why does she have menstruation every month?

Coming of menstruation (periodical excretions with blood from genital tracts) is a sign of pubescence. One menstrual cycle lasts between the first day of last menstruation to the first day of the following one. Rhythmically repeating changes prepare organism for pregnancy. As a rule, menstrual cycle lasts 28 days, rarer 21 or 35 days. Due to cyclic influence of gonadotropic hormones (cerebrum glands), marked changes in uterus, ovaries, mucous membrane of vagina, cervix of the uterus and tubes take place. Pituitary hormones provide regular menstrual cycles. Vegetative centers of hypothalamus make secretion of these gonadotrophins more active. Rhythmical changes in ovaries take place in phases.
  
Follicular phase: growth of follicle and break of ripening follicle. The main component of follicle is ovule, which becomes free after follicle breaks and is ready for insemination. At the same time oestrogens hormones are produced in ovaries, which influence genitals and whole female organism. Under their influence muscles of uterus, excretory duct of lacteal gland and mucous membrane of vagina change. All changes cause hypersthenia, excitability and frequent uterismus.
  
Ovulation. This period is most favorable for insemination (13th-15th days of cycle). Break of whole follicle and coming out of ovule (which comes to abdominal cavity and then to uterus through fallopian tube) take place.
  
Lutein phase. It comes after ovulation. Internal secretion gland – yellow body – is formed instead of broken follicle, this yellow body produces progesterone hormone. If ovule, which came out from follicle, is inseminated, then yellow body is functioning during first months of pregnancy (yellow body of pregnancy). If pregnancy hasn’t come, then back development starts since 28th day of cycle, it is called yellow body of menstruation, i.e. if there’s no pregnancy – menstruation begins.
  
Yellow body hormone – progesterone contributes to appearance and development of pregnancy. Its secretion is necessary for changes of mucous membrane of uterus, which contribute to fastening and development of oosperm. Progesterone reduces excitability and sensitiveness of uterus, what is necessary to keep pregnancy. If pregnancy hasn’t come, yellow body is subjected to back development, and making of progesterone stops. Under the influence of ovary hormones cyclic changes in uterus take place, especially in endometrium. Uterine cyclealso lasts 28 days.
  
Since the first day of menstruation a functional layer of mucous membrane breaks apart, is torn away and secreted with blood from broken vessels. Menstruation usually lasts 3-5 days and clashes with beginning of death of yellow body in ovary. Then mucous membrane is restored, grows and thickens 4-5 times under the influence of estrogenic hormones.
  
Phase of secretion – development and bloom of yellow body - lasts since 14-15th day and until the end of cycle. Under the influence of progesterone (produced by yellow body) qualitative changes  take place in uterus again: secretory glands increase, metabolism is increased in mucous membrane, activity of ferments rise, i.e. favorable conditions for development of future embryo are created again.
  
If pregnancy hasn’t come, yellow body dies, functional layer of mucous membrane of uterus is torn away and menstruation begins. New cyclic changes in uterus, ovary and whole organism take place again. Pregnancy begins since the moment of insemination. This is a process of confluence of male spermatozoon and female ovule. Spermatozoa come to uterine cavity, moving independently, then to uterine tubes, where they meet ovule. After ovulation, ovule can be inseminated during the period from 12 to 24 hours. Only one spermatozoon takes part in insemination. After confluence with ovule zygote is formed, which has dual inheritance, mother’s and father’s one, and can multiply and grow actively. An embryo is formed, a beginning of a new live organism. Spermatozoa, which didn’t come to ovule, die, break apart and are absorbed by mucous membrane of tubes.  

Attention! Beginning of menstruation means a girl’s readiness for reproduction. Nature created a unique mechanism, contributing to continuation of family. Female organism is working hard constantly with one single purpose – to inseminate ovule, bear embryo and give birth to a baby.  



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