What is menstruation? Explain.

Hint: Reproductive or sexual cycle are the monthly cycles occurring in the females. The reproductive cycles prepare the reproductive system of the female for pregnancy and development of the implanted embryo. It involves the activity of various reproductive organs such as uterus, ovaries, vagina and glands such as the hypothomes, hypophysis and the mammary glands.

Complete answer:
A fertile female exhibits two types of periodic cycles which are the ovarian cycle and the menstrual cycle. Menstruation cycle takes place in the endometrium of the uterus. It is the monthly discharge of blood and mucosal tissues shed from the inner lining of the uterus. It is also known as period or monthly as it occurs once in a month and is the most visible phase of the menstrual cycle.

The onsetting of the menstruation usually begins between twelve to fifteen years of age and marks the fertile period of the female. It occurs usually up to forty-five to fifty-five years of age and after that the discharge is stopped. This phase is known as menopause or stopping of menstruation. Menstruation is also stopped during the pregnancy which does not resume for some initial months of breastfeeding.

The first day of the menstrual cycle is the date used for the last menstrual period. Its beginning is used as the marker between two cycles. The menstrual cycle is affected due to the rise and fall of hormones. During this cycle after the formation of the ovarian follicles the internal lining of the uterus thickens. Subsequently growth of the egg takes place and the uterus begins to prepare for implantation provided the egg is fertilized by the male sperm. This condition is required for pregnancy. The egg released from an ovary at around fourteen day in the cycle. The thick lining of the uterus provides necessary nutrients to an embryo after implantation. If fertilization and implantation does not take place, the lining of the uterus breaks down along with the blood vessels and is released through the discharge known as menstruation. The menstruation is also under the control of hormones such as progesterone and estrogen which falls and causes the corpus luteum to degrade and finally menstruation occurs.

Note: Menstruation is the monthly periodic discharge from the vagina of the females caused due to the shedding of the thickened lining of the uterus in absence of pregnancy. In the case of no fertilization, implantation of the embryo does not take place and the levels of hormones such as estrogen and progesterone fall rapidly and the corpus luteum degrades. As a result, the thickened lining of the uterus is disintegrated and is discharged as menstruation blood.