Menstrual Cycle

Question 1

menstrual (uterine) cycle overview

Answer 1

• closely integrated with ovarian cycle
• regulated by ovaries releasing estrogen + progesterone monthly to change the endometrium in preparation for potential implantation
• 3 phases

Question 2

3 phases of menstrual cycle

Answer 2

1. menstrual phase
2. proliferative phase
3. secretory phase

Question 3

menstrual phase

Answer 3

• days 1-5
• all endometrium sheds except basal layer
• menstrual flow travels from uterus –> vagina & exits body via vaginal orifice

Question 4

menstrual flow

Answer 4

detached endometrial tissue and blood

Question 5

proliferative phase

Answer 5

• days 6 - 14
• estrogen levels increase, causing endometrium to rebuild
• increased estrogen triggers ant. pit gland to release LH at ~day 14 –> ovulation

Question 6

secretory phase

Answer 6

• days 15-28
• corpus luteum starts secreting progesterone
• dies if egg is not fertilized

Question 7

progesterone’s affect on endometrium

Answer 7

• increased blood supply to uterus & nutrient secretion

- when goes away (if egg not fertilized) endometrium blood supply decreases –> ready for menstrual phase