Menstrual Cycle.

 

Female menstrual cycle

Female menstrual cycle is a natural process that occurs monthly in a women’s body preparing for pregnancy and it included the release of an egg, thickening of uterine lining and shedding of the uterine lining.

Mostly the cycle is 28days there can be some women which their cycle is 21days or 35days.

If the cycle is less than 21 days is called Polymenorrhea.

Polymenorrhea is mostly caused by :

1: hormonal imbalance irregular levels of estrogen and progesterone.

2: anovulatory cycle is when no ovulation occur and progesterone not produced.

3: perimenopause hormone levels drop as women approaches menopause.

4: thyroid disorders it can be caused both hypothyroidism and hyperthyroidism 

5: stress or sudden weight changes it can be hypothalamic or pituitary or ovarian axis.

6: uterine conditions like fibroid, polyps, endometriosis can cause irregular cycle.

7: uses of hormonal contraceptives especially started or stopped recently.

8: adolescence in young girls cycle maybe irregular foe some years

If the cycle is more than 35 days Oligomenorrhea.

Oligomenorrhea mostly caused by

1: polycystic ovarian syndrome is caused by high estrogen level which disturbs ovulation.

2: thyroid disorders it can be caused by both hypothyroidism and hyperthyroidism.

3: hyperprolactinemia is high level of prolactin which usually elevates in pregnancy and breast feeding.

4: excessive exercise (athlete’s traid) it is when body fat low and overtraining suppress estrogen and effect the menstruation.

5: pituitary or hypothalamic dysfunction is brain related hormone regulation problems 

6: hormonal birth control can include pills, injections, IUDS.

What is happening in the body:

Hypothalamus plays highest role in female monthly cycle.

Hypothalamus produce gonadotrophic hormone releasing factor and stimulates anterior pituitary gland and produce gonadotrophin hormone.

Gonadotrophin hormone releases follicular stimulating hormone and luteinizing hormone.

And FSH is going to work in the ovaries.

There are 4 phases in female cycle

1: Menstrual phase: it is when the period starts day 1-5 and the uterus sheds it is lining and also estrogen and progesterone are low in this phase.

2: Follicular phase: pituitary gland releases follicle stimulating hormone and it stimulates the growth of follicles in the ovaries. Estrogen levels begin to rise and rebuild the uterine lining. Day 1-13

3: Ovulation phase: mostly day 14 the mature follicle releases an egg.

4: Luteal phase: corpus luteum forms from the empty follicle and secretes progesterone. Day 15-28.

Corpus luteum function:

1. it produces progesterone: that progesterone will go the uterine and cause Secretary changes in uterine endometrium.

after ovulation will give negative feedback of FSH and LH releasing so LH level decrease as LH level are decreasing corpus luteum degenerate ➡ progesterone levels decrease and the Secretory changes in the endometrium can not be there and shedding of uterine endometrium happen.

Usually normal menstruation is associated with pain (menstrual cramps).

Mostly the maximum amount of progesterone secretion seen on day 22nd of menstrual cycle

Progesterone also gives negative feedback of releasing FSH.

2: corpus luteum also produces estrogen

3: corpus luteum also produces inhibin A

Hypothalamus releases ➡ gonadotrophic hormone releasing factor which acts on ➡ anterior pituitary and produce ➡ Follicular stimulating hormone (FSH) and go to the ➡ follicles (especially granulosa cells) and help production of estrogen.

Estrogen is doing important work

1: estrogen will give negative feedback of releasing FSH.

2: estrogen will go to the uterus and endometrium cells start multiplying and cause endometrium proliferation.

3: estrogen gives positive feedback of luteinizing hormone.

Luteinizing hormone function:

1: Luteinizing hormone will go granulosa cells and produce progesterone

Progesterone will cause positive feedback of FSH and LH.

2: luteinizing hormone go to interna theca cells and produce androgen.

Androgen moves to granulosa cells and will be converted to estrogen.

3: luteinizing hormone will act on mature follicle graafian follicle and rupture the follicle.

There are many stages of follicular growth and development.

1: primordial follicles is a resting stage which formed before female born in their mother’s womb. It  has primary oocyte and surrounded by a single layer of flat granulosa cells.

2: primary follicle is activated at puberty stage and oocyte develop and also granuolsa cells become cuboidal and zona pellucida layer starts it is formation.

3: secondary follicle is is a stage when estrogen production begins and further development and theca cells will develop in this stage of follicle.

4: Tertiary (Antral) follicle is the stage of formation of the fluid filled cavityestrogen production increase and follicles growth rapidly.

5: graafian follicle is the stage which an egg will be prepared to release from the ovum .

6: ovulation is the stage where an egg is released from the ovum .

7: corpus luteum is the stage after egg was released and starts secrete progesterone.

8: corpus albicans this stage is if no fertilization occurred and hormone level drop that will cause degeneration of corpus luteum and triggers the menstruation begin or period.

So what happens to the menstrual cycle if fertilization occur?

First the fertilized egg zygote will travel to the uterus and starts implantinting in the uterus lining about 6-10days after ovulation.

Secondly the embryo produces Human chorionic gonadotrophin that will be good for corpus luteum and keep it alive and it will continue producing progesterone and estrogen to help the pregnancy.

Thirdly there will be no menstruation because of high level of estrogen and progesterone it will pause the menstruation also the hormones will inhibit the secretion of follicular releasing hormone and luteinizing hormone.

Fourthly around 10-12 weeks of gestation placenta will take over producing of estrogen and progesterone from corpus Luteum and corpus Luteum will degenerate naturally.

Conclusion

The female menstrual cycle or female monthly cycle is a monthly hormonal process which body prepares of pregnancy and usually involves the interaction which happens between brain (hypothalamus and pituitary) and ovaries and uterus.

A regular cycle is a sign of hormonal ad reproductive health.