Menstrual Cycle~Quick Facts

• The Menstrual cycle is a feedback mechanism because it is regulated by hormones which are controlled by negative feedback mechanisms. This mechanism includes hormones that are interacted with tissues in the menstrual cycle.
• The female menstrual cycle is determined by a complex interaction of hormones. The predominant hormones involved in the menstrual cycle are:

1-gonadotropin releasing hormone (GnRH),
2-follicle stimulating hormone (FSH),
3-luteinizing hormone (LH),
4-estrogen, and progesterone.

• GnRH is secreted by the hypothalamus, the gonadotropins FSH and LH are secreted by the anterior pituitary gland,and estrogen and progestin are secreted at the level of the ovary.
• GnRH stimulates the release of LH and FSH from the anterior pituitary, which in turn stimulate release of estrogen and progestin at the level of the ovary
• Follicle stimulated hormone (FSH) is secreted by the anterior pituitary gland and is essential for follicular growth
• FSH induces estrogen and progesterone secretion and has negative feedback on GnRH secretion.
• Estrogen is produced at the level of the ovary and is crucial for the development of and maturation of the Graafian follicle.
• At low circulating levels, estrogens exert negative feedback on LH and FSH secretion; however, at very high levels estrogens exert positive feedback on LH and FSH secretion.