Monday, April 8, 2013

Hormones that Regulate Menstrual Cycle

Hormones that Regulate Menstrual Cycle

Hormones controlling Menstrual Cycle 
Like any other body processes, hormones are involved at every stage of the menstrual cycle. Hormones work like messengers that travel in the bloodstream to transport signals from one cell to another. During the women’s monthly period, several hormones are responsible for the control of the menstrual cycle. The menstrual cycle in women is a recurring process in which the lining of the uterus is prepared for pregnancy, and if pregnancy does not happen, the lining is shed at menstruation.

There are four essential hormones in control namely the Gonadotropic Hormones
which are the follicle stimulating hormone (FSH) and luteinizing hormone (LH) and the Ovarian Hormone composed of estrogen and progesterone.

The gonatropic hormones are completely responsible for the changes in the ovaries during the menstrual cycle. In fact, the deficiency of it during childhood is the reason why pregnancy until puberty is impossible. As puberty starts, the pituitary gland releases these hormones in increasing quantities. FSH and LH stimulate cell receptors that trigger the growth of the ovaries and other follicles.

During the beginning of the menstrual cycle, the pituitary gland releases FSH and LH which starts the development of one egg in a follicle in one of the ovaries. The ovary then produces oestrogen which causes the repair of the lining of the uterus after the last menstruation. The pituitary now produces LH which causes ovulation which is the release of the ovum from the mature dominant primary follicle. Once the ovum is released, the ruptured follicle, now called the corpus luteum, starts secreting the ovarian hormone, estrogen and progesterone.

Estrogen and progesterone influence the changes that occur in the endometrium, the inner lining of the uterus. In the first half of the cycle before ovulation, the cells of the endometrium grow and proliferate rapidly. The endometrium increases in thickness. There is also an increase in the number of glands and new blood vessels in the endometrium. The glands start to secrete mucus. All these changes occur under the influence of the hormone estrogen.

During the second half of the cycle, after ovulation, the endometrium undergoes further changes under the influence of progesterone. There is marked swelling of the endometrium and growth of new blood vessels. There is a buildup of the endometrium towards the end of the monthly cycle. If the egg is not fertilized, production of estrogen and progesterone stops, the lining of the uterus breaks down and menstruation occurs.

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