Physiology of the Menstrual Cycle

The menstrual pedal is a cyclic process in females that, on average, occurs every 28 daylights. The purpose of the menstrual round of golf is to help prep ar the body for potential fertilization, implantation, and, consequently, pregnancy. The happenings of the menstrual roulette wheel atomic number 18 consequences of the simultaneously occurring ovarian wheel and uterine one shot. The ovarian cycle occurs in the ovaries and carries break the follicular signifier, which spans the first 14 age of a new menstrual cycle. The issuing is ovulation.The uterine cycle works concurrently with the ovarian cycle and carries let on the menstrual, proliferative, and secretory builds. Hormonally, gonadotropin-releasing hormone (GnRH) is released in the hypothalamus and travels to the foregoing pituitary body of the virtuoso, thus increasing levels of follicule-stimulating hormone (FSH) and leutinizing hormone (LH). The brain acts directly on the follicle cells (in the follicular phase) and the principal luteum (in the luteal phase) to stimulate a response.The result of hormonal secretions of the hypothalamus and anterior pituitary along with the ovarian and uterine cycle is flow. The overall cycle is regulated by the hormones that result from a release of GnRH from the brain. Negative feedback occurs in the too soon follicular phase and luteal phase of th ovarian cycle as GnRH is released, which causes an increase in FSH and LH levels in the anterior pituitary. In the early follicular phase, these hormones send signals through neurotransmitters that action receptors on follicle cells and follicular development is enhanced.Simultaneously, plasma levels of oo estrogen increase and return to the brain to hinder keep LH and FSH secretion. At the end of the follicular phase, positive feedback occurs as towering estrogen levels are passed back to the brain and estrogen continues to amount to high levels. In the luteal phase, the brain sends hormonal signals to the lead luteum. As a result, levels of estrogen and progesterone are heightened and progesterone is fed back to the brain to state stable levels of LH and FSH.This demonstrates how brain function and hormonal regulation carry out essential, complex processes in the body, such as those of the menstrual cycle. The ovaries originally acquit primordial follicles, which are made up of an oocyte (an fledgeless egg) and a layer of follicle cells that envelops it. In the beginning stages of the follicular phase of the menstrual cycle, some of these follicles start to develop, neat granulosa cells. A fluid-filled cavity called an antrum appears in the follicle and begins to increase in size only to eventually engulf the oocyte.The follicle is directly called the Graafian follicle, which soon bursts, and the oocyte leaves the ovary and travels into the fallopian tube, spurring ovulation. The leftover Graafian follicle proceeds what is called the corpus luteum. The corpus luteum (y ellow body) is a gland that secretes estrogen and progesterone when the menstrual cycle is not in full swing. If fertilization of the oocyte ensues, the corpus luteum remains inviolate for a fair amount of time in order to regulate the release of estrogen and progesterone.If the oocyte fails to become fertilized, the corpus luteum will disintegrate relatively quickly. At the point of the follicle rupturing, there is a major plait in LH and FSH plasma levels. The uterine cycle is carried out in three phases. The menstrual phase begins on the first day of the menstrual cycle and corresponds with the follicular phase. It lasts about three to quin days and sheds the uterine lining. During this phase is when actual menstruation occurs due to a decline in estrogen and progesterone plasma levels that occurred because the corpus luteum had fully deteriorated.The informal lining of the uterus, the endometrium, has telephone circuit vessels that now narrow and the endometrial tissue beg ins to die and shed from the uterus. As it sheds, job vessels burst and blood and tissue are dispelled from the vagina. The proliferative phase is next and allows the uterus to refurbish as blood vessels become engulfed again, allowing the uterine lining to thicken. It occurs around day five and lasts until day fourteen, when ovulation has happened. During the proliferative phase, estrogen levels peak.The next phase is the secretory phase, which creates a setting that readily allows for embryo development as glands become engorged due to increased blood flow and secrete fluids that cop glycogen that may act as a food source of glucose for a potential embryo. The secretory phase lasts about the last fourteen days of the menstrual cycle-at the same time as the luteal phase. By the end of this cycle, the corpus luteum has completely debased and, because it can no longer act as a source of stimulation for estrogen and progesterone release, these two hormone levels drop and menstruat ion commences as the menstrual phase begins again.Works Cited Bowen, R. Luteinizing and Follicle Stimulating Hormones. Arbl. cvmbs. colostate. edu. 13 whitethorn 2004. Web. 09 Feb. 2011. . Cohen, Hilary. Menstrual Cycle Home. Endocrinology of the Menstrual Cycle. 2000. Web. 09 Feb. 2011. . Stanfield, Cindy L. , William J. Germann, Mary Jane. Niles, and Joseph G. Cannon. Principles of kind-hearted Physiology. San Francisco Pearson/Benjamin Cummings, 2008. Print.