Topic 7: Endocrine System: Ovarian/Uterine Cycle

Question 1

What occurs in days 1-14? (2)

Answer 1

Ovary: Follicular (preovulatory) phase
Uterus: Menstrual phase and Proliferative phase
same time as each other!!

Question 2

What occurs in the follicular (preovulatory) phase? (5)

Answer 2

• ovary
• early on, P is low, so LH and FSH is secreted
• some primary follicles turn to secondary follicles due t FSH
• Follicles secrete E so blood E rises
• Later on, one (usually) secondary follicle becomes a vesicular follicle

Question 3

What occurs in the mestrual phase? (3)

Answer 3

• days 1-5
• stratum functionalis shed (outer layer of endometrium) and denuded areas bleed
• therefore menstrual flow is blood, cells, and secretions
  note that u still have basal layer since cells still need to undergo mitosis

Question 4

What occurs in the proliferative phase? (2)

Answer 4

• days 6-14
• Estrogen causes repairs and proliferation of stratum functionalis due to mitosis in stratum basalis

Question 5

What occurs on day 14?

Answer 5

• ovulation

Question 6

Why does ovulation occur? (3)

Answer 6

• due to LH surge
• LH triggers completion of meiosis I to secondary oocyte
• also triggers rupture of vesicular follicle with release of secondary oocyte

Question 7

What occurs during days 15-28?

Answer 7

-Ovary: Luteal phase
Uterus: Secretory phase

Question 8

What occurs in the luteal phase? (3)

Answer 8

• ovary
• High P from corpus luteum inhibits GnRH (therefore LH and FSH too)
• then no follicles develop

Question 9

What occurs in the secretory phase? (4)

Answer 9

• uterus
• Progesterone from corpus luteum prepares endometrium for implantation
• endometrium becomes vacular, thick and stores glycogen
• P also inhibits uterine contractions

Question 10

What happens if fertilization occurs? (3)

Answer 10

• placenta secretes human chorionic gonadotropin (hCG) which maintains corpus luteum (similar structure to LH)
• corpus luteum releases P. E for about 6 weeks, then placenta takes over and secretes them
• FSH, LH inhibited by high P (no new follicles develop)

Question 11

What happens if NO fertilization occurs? (4)

Answer 11

• corpus luteum turns to corpus albicans where no hCG and low LH
• therefore decreased P and E,
• and therefore no longer inhibit LH, FSH, so they increase
• no longer maintain endometrium, so menstruation occurs