Menstrual Cycle Michal Ovecka
Introduction • Unlike some animals, Humans can reproduce during any time of the year • In the females this involves the menstrual cycle - production of an oocyte inside the follice • Thickening of the lining of the uterus • When no embryo is formed, the thickening is broken down and passed out of the body during menstruation
Phases of the Menstrual cycle • Follicular phase • Ovulation • Luteal phase • Menstruation
Follicular phase • Pituitary gland secretes FSH
Follicular phase • Stimulating a group of follicles, the containing eggs and estrogen secretion by cells of the follicles • While the eggs are going through development the lining of the uterus (endometrium) begins to repair, due to increasing levels of estrogen • Estrogen levels reach a peak, thus stimulating LH secretion by the pituitary gland
Ovulation • LH rises to a peak causing the most developed follicle to release an egg into the oviduct (the other follicles degenerate) • LH causes the follicle cells to secrete less estrogen and more progesterone. • The LH causes the follicle which released the egg to develop into corpus luteum. • The corpus luteum secretes progesterone which develops the endometrium • The development of the endometrium prepares the egg for the implantation of an embryo
Menstruation • High levels of progesterone and estrogen levels inhibit FSH and LH secretion • If fertilization does not occur, the corpus luteum degenerates and the lining of the uterus breaks down - for shedding during menstruation
Bibliography • http://upload.wikimedia.org/wikipedia/commons/a/a5/Hypophyse.png • http://www.ux1.eiu.edu/~cfjcd/Menstrual_Cycle.pdf • https://www.theeveningjava.com/images/femalerepro..jpg • Allot, Andrew. IB Study Guides Biology. Second ed. Glasgow: Oxford UP, 2007. Print.