BIO 12 UNIT 3: Study Notes

Sequence of Events in Ovarian Cycle

1) Follicular phase: Follicle develops due to FSH released from the pituitary gland, this results in the the follicle producing estrogen and progesterone

2) Ovulation: occurs in midway of cycle (day 14), egg is released into the oviduct due to a surge in LH levels from the pituitary gland. 

3)Luteal Phase: Corpus luteum is formed from follicle remains, this produces progesterone and estrogen.If the egg is not fertilized during ovulation the corpus luteum disintegrates due to low levels of estrogen and progesterone and menstruation occurs at the end of this phase

Sequence of Events in Uterine Cycle

1) Menstrual Phase: Decreased levels of progesterone and estrogen due to break down of coprus luteum cause the endometrium to break down during days 1-5 of the cycle

2) Proliferation Phase: Endometrium rebuilds and thickens because of the developing follicle producing estrogen at the ovary. (Days 6-14)

3) Secretory Phase: Endometrium thickens and mucus is secreted, this is caused by the corpus luteum producing progesterone (Days 15-28)

http://www.youtube.com/watch?v=WGJsrGmWeKE&feature=related (video on the Menstrual Cycles)