Why does a woman experience regular cyclic changes? Why does she have menstruation and ovulation every month? Coming of menstruation (periodical excretions with blood from genital tracts) is a sign of pubescence
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.This means ovulation.
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)
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
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.
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
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.
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.
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
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