Female Hormone Regulation
Reminder Hypothalamus secretes GnRH GnRH stimulates anterior pituitary to release FSH and LH
FSH function in females Responsible for follicular phase FSH stimulates maturation of ovum in ovary Ie) “Stimulates follicle”
LH function in females LH stimulates the follicle cells (more specifically corpus luteum) to produce progesterone and estrogen
Progesterone Hormone Controls the secretory phase Stimulates maturation of the endometrium (inner lining of uterus) Breast development
Estrogen Hormone Controls proliferative phase Building of endometrium Stimulates the maturation of ovum as well Develops 2° sex characteristics Fat & hair distribution Growth of uterus & vagina Breast development
Estrogen Hormone When estrogen gets too high it creates a “-” feedback loop on anterior pituitary Causes a decrease in LH & FSH Ie) this is meant to prevent estrogen levels from getting too high
Estrogen Hormone Day 14, when the follicle matures and estrogen levels are the highest, there is a steep spike in LH (and also FSH) Believed that the significantly high level of estrogen creates a POSITIVE feedback on hypothalamus This causes the surge of LH (and FSH) = ovulation results
Corpus Luteum The remaining follicular tissue after ovulation Secretes progesterone & after a few days estrogen Progesterone stimulates the endometrium to mature and become secretory Estrogen stimulates continual thickening of endometrium wall This prepares the uterus for possible fertilization & pregnancy
Corpus Luteum Corpus luteum degenerates after 10 days if not pregnant This reduces the estrogen/ progesterone and the endometrium sheds as a result =menstruation Lasts ~5days and anterior pituitary begins releasing LH & FSH again Starts new cycle
Ovarian Cycle Phase (Time) Events Follicular Phase Day 1-13 (ripening of follicle) FSH & LH secreted by An Pit Maturation of follicle Secretion of estrogen/ progesterone to build endometrium Ovulation Day 14 Ovary releases ovum Corpus luteum formed Luteal Phase Day 15-28 (corpus luteum in ovary) Estrogen secreted by corpus luteum causing endometrium to continue to thicken Progesterone secreted by corpus luteum makes endometrium secretory
What happens in the ovarian phase causes the uterine phase
Uterine Cycle Phase (Time) Events Menstrual (Flow) Phase (shedding of endometrium) Day 1-5 Endometrium lining breaks down & is discharged = menstruation Proliferative Phase (rebuilding of uterine lining) Day 6-14 Rebuilding & thickening of endometrium Secretory Phase Day 15-28 Endometrium continues to thicken Maturation of secretory glands of endometrium
Key Ideas Hypothalamus and An Pit controls OVARY by secreting FSH & LH Ovary ripens egg & release on day 14 Ovary secretes estrogen/ progesterone OVARY controls UTERUS by way of estrogen/ progesterone
Ovarian & Uterine Cycle