Hormonal control of human female reproductive function The Menstrual Cycle or Ovarian Cycle

The human female is fertile only during a few days of each and every month. The hypothalamus secretes gonadotropin releasing hormone(GnRH) . It acts on anterior pituitary gland. It secretes FSH ( Follicle stimulating hormone) and LH ( luteinizing hormone). These hormones controls the release of oocyte and menstrual cycle. These hormones also controls two cycles:

1.Menstrual Cycle


The cyclic preparation of the uterus for receiving a fertilized ova or egg is called menstrual cycle.

2.Ovarian cycle


The cycle during which the oocyte becomes mature and ovulation occurs called ovarian cycle.

Menstrual cycle begin at puberty.

For the fertilized egg, it prepare the uterine lining monthly.

The ovaries lose their sensitivity of releasing FSH and LH at the age of 45 to 55 years.  They stop producing normal quantity of estrogen & progesterone.

Menopause


The complete stoppage of menstrual cycle is called menopause. Its due to environmental stresses and age.

Generally, In young women, One menstrual cycle is completed in 28 days. But it range maybe from 22 to 28 days.

Following processes take place during this timeperiod.


1:- Release of GnRH hormone/ Role of Hypothalamus


Gonadotropin releasing hormone is released by hypothalamus. Hypothalamus acts as a controlling centre for menstruation & ovulation. GnRH stimulates the anterior pituitary to release Follicle stimulating hormone & luteinizing hormone.

2:- Role of follicle stimulating hormone {FSH}:-


In one of the ovarian follicles , it promotes the development of the oocyte.

3:- Role of Estrogen hormone:-


Estrogen is a hormone and it released by follicles. It inhibit the production of FSH.  It also develops the endometrium.

4.. Role of luteinizing hormone (LH):-


High level of estrogen stimulates the anterior pituitary to release LH. It matures the follicles. It enlarged them rapidly. Follicles releases the secondary oocyte during ovulation finally.

Corpus leuteum


The broken follicles are called corpus leuteum.

5.. Role of corpus leuteum


It secretes estrogen & progesterone. Development of endometrium is completed by them.

6.. Corpus albicans:…


If oocyte isn't fertilized , the corpus leuteum degenerates into a corpus albicans. It exit the estrogen & progesterone secretions.

7⇒Break down of endometrium:-


Without estrogen & progesterone endometrium is broke down. Thus menstruation begins. Menstrual flow is composed of endometrial cells, blood & mucus.

8--> Repeating of cycle:-


The progesterone & estrogen level decreased,. The pituitary glands agin starts the secretion of FSH. It stimulate the development of another follicle . Thus new monthly cycle is repeated.

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