Simple way to understand Menstruation

Menstruation is a very complex process. To understand the  menstruation process we should first know the major players  involved in this whole process, these are female sexual organs,  nervous system and hormones.  


– Uterus (womb) Uterus is attached to the cervix and the vagina, and has the Fallopian tubes on either side. The primary function of the uterus is in reproduction; the conduit for sperm transport,  the site for implantation of fertilized ova, placentation, growth and development of the foetus, and parturition (labor and delivery).

– Ovaries The ovaries are a pair of female reproductive organs. They are located in the pelvis, one on each side of the uterus. The ovaries are connected to each other by the Fallopian tubes. The ovaries have two functions:

Produces eggs (also called ova): the ovaries contain  eggs which are kept in the sacs called follicles.  During each period, a single egg will usually ripen and mature due to the action of hormones circulating in the bloodstream.

Produces female hormones (estrogen and progesterone): These hormones controls the development of female body characteristics, such as the breasts, body shape, and body hair. The ovaries also regulate the menstrual cycle and pregnancy

– Fallopian tubes The fallopian tube is the tube which connects the ovaries to the uterus. When the egg is mature it bursts from the ovary and drifts through the Fallopian tube down into the uterus.


– Hypothalamus An area of the brain just above the pituitary gland. It is control center for all autonomic regulatory activities of the body. It manages all endocrine hormonal levels, sensory processing, and organizing body metabolism; as well as it organizes and controls many complex emotions, feelings and moods, as well as all motivational states including hunger, appetite and food intake, and everything to do with the concept of pleasure including satisfaction, comfort and creative activities.

– Pituitary gland A little gland situated below the hypothalamus. Hormones secreted by the pituitary stimulate and control the functioning of almost all the other endocrine glands in the body. Pituitary hormones also promote growth and control the water balance of the body.

C. HORMONES There are five major hormones involved in menstruation.

Follicle Stimulating Hormone (FSH) Secreted by the anterior pituitary gland, during the first half of the menstrual cycle.  It helps in development of Graafian follicle.

Luteinizing Hormone (LH) Secreted by the pituitary gland, it Stimulates ovulation and helps in development of corpus luteum and thickens the endometrium.

Estrogen Secreted by ovaries, adrenal cortex and by the placenta during pregnancy. It Stimulates thickening of the endometrium, causes suppression of FSH secretion, Assist in maturation of ovarian follicles.

Progesterone Secreted by corpus luteum and placenta during pregnancy. It Inhibits secretion of LH and Maintains thickness of endometrium

Prostaglandin Produced by many organs of the body, including the endometrium. It affects menstrual cycle, influences the onset and maintenance of labor

Menstrual cycle

It can be divided into three different phases – the follicular phase ovulation and the luteal phase. These different phases of the menstrual cycle have different functions.

– The follicular phase (days 1 to 13). It’s called the follicular phase because growth or maturation of the egg is taking place inside the follicle ( a small sac where the egg matures) and the two hormones dominating the follicular phase are follicle-stimulating hormone (FSH) and estradiol (a form of Oestrogen)..

– In this phase the endometrium (lining of the uterus) grows and thickens and several ovarian follicles develops, of which one becomes dominant before ovulation.

– Ovulation Ovulation is the key event of the menstrual cycle, occurs around day 14 of the cycle, in response to a surge of Luteinizing hormone (LH) when the egg is released from the ovary, and can only be fertilized for up to 48 hours. It is important to accurately identify when you are ovulating if you are trying for a baby in order to maximize your chances of getting pregnant.

– Luteal phase The luteal phase is the time from when the egg is released (ovulation) till the first day of menstruation

– After ovulation, (release of mature ovum from the Graafian follicle) Cavity of the Graafian follicle is replaced by the corpus luteum (secretes progesterone and some estrogen)

– Progesterone acts upon the endometrium to bring about secretary changes that prepare it for pregnancy.

– If fertilization does not occur the corpus luteum in the ovary begins to regress due to which Production of progesterone and estrogen decreases and finally Endometrium of uterus begins to degenerate and slip away and menstruation begins.

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