The Menstrual Cycles Phase and It's Hormones Functions | Anatomy Notes | BSc Radiology, BXRT Notes

The Menstrual Cycles Phase And It's Hormones Functions : मासिक धर्म चक्र चरण और इसके हार्मोन कार्य

• What is the Menstrual cycle ?

The menstrual cycle prepares your body for pregnancy. If you are not pregnant, your hormones send a signal to your uterus to shed its lining. This becomes your period. Once you start your period, the cycle starts again.

A menstrual cycle is measured from the first day of your period to the first day of your next period. The average length of a menstrual cycle is 28 to 29 days, but every woman’s cycle is different. For example, teenagers might have cycles that last 45 days, whereas women in their 20s to 30s might have cycles that last 21 to 38 days.

Your first period is called Menarche. the average age for a first period is 12 to 13, but it can start as early as nine and as late as 16.

Your last period is called Menopause. the average age for women to reach menopause is 51 to 52. Some women might reach menopause as late as 60.



• Hormones involved in the menstrual cycle are :

1. Follicle-Stimulating Hormone (FSH) :-

FSH is released by the pituitary gland in the brain and stimulates the growth and development of ovarian follicles in the ovaries. These follicles contain the eggs.

2. Estrogen :-

As the ovarian follicles grow, they produce estrogen. Estrogen is responsible for thickening the lining of the uterus (endometrium) and promoting the maturation of the eggs.

3. Luteinizing Hormone (LH) :-

As the menstrual cycle progresses, the levels of estrogen increase, causing a surge in LH. The LH surge triggers ovulation, which is the release of a mature egg from the ovary into the fallopian tube.

4. Progesterone :- 

After ovulation, the empty follicle in the ovary transforms into a structure called the corpus luteum, which produces progesterone. Progesterone helps prepare the uterine lining for implantation of a fertilized egg. If fertilization doesn't occur, the corpus luteum breaks down, leading to a drop in progesterone levels.

• Let's explore the menstrual cycle in simple terms :

1. Menstruation :-

   - The cycle starts with menstruation (period), which is the shedding of the lining of the uterus.
   - This happens when a mature egg from the previous cycle was not fertilized by sperm.

2. Follicular Phase :-

   - After menstruation, the body starts preparing for a new cycle.
   - The brain releases a hormone called follicle-stimulating hormone (FSH).
   - FSH helps the ovaries to develop egg-containing sacs called follicles.
   - These follicles produce a hormone called estrogen, which thickens the uterine lining.

3. Ovulation :

   - Estrogen levels rise and trigger the release of another hormone called luteinizing hormone (LH).
   - The surge in LH causes the release of a mature egg from one of the follicles.
   - This is called ovulation, and the egg travels into the fallopian tube, where it can be fertilized by sperm.

4. Luteal Phase :

   - After ovulation, the empty follicle forms a temporary structure called the corpus luteum.
   - The corpus luteum produces a hormone called progesterone.
   - Progesterone helps prepare the uterus for pregnancy by thickening the lining further.
   - If fertilization doesn't occur, the corpus luteum breaks down, and hormone levels drop.

5. Menstruation :

   - If the egg is not fertilized, the hormone levels decrease, and the thickened lining of the uterus is no longer needed.
   - The uterus sheds this lining, and a new menstrual cycle begins.

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