Menstrual Physiology

Question 1

How many phases in ovarian cycle and what are they?

Answer 1

2 (3 if pregnancy included)

• Follicular phase
• Luteal phase

Question 2

What happens in follicular phase?

Answer 2

Primordial follicles arrested at prophase I

• FSH from anterior pituitary stimulates a number of primordial cells to begin maturation
• As granulosa cells mature they increase in size and number and secrete oestrogens which drive cycle

-After 13ish days dominant follicle develops and in creases in size: LH surge leads to ovulation

Question 3

What happens to left over follicle in luteal phase?

Answer 3

Partially collapses and forms corpus luteum

Question 4

What does corpus luteum do?

Answer 4

Secretes oestrogen and progesterone

-If fertilization doesn’t occur the corpus luteum regresses so progesterone secretion falls, endometrial lining is shed and cycle can begin again

Question 5

If fertilization occurs?

Answer 5

HCG production from trophoblast maintains corpus luteum formation until 10-12 weeks of gestation

-By which time placenta will be making sufficient oestrogen and progesterone to support self

Question 6

Average uterine cycle length?

Answer 6

28 days

Question 7

Day 1-3 called?

Answer 7

Menstrual phase

Question 8

What happens in menstrual phase?

Answer 8

Withdrawal of hormones result in shedding of endometrial lining

Question 9

Day 1-14 is what phase?

Answer 9

Proliferative phase

Question 10

What happens in proliferative phase?

Answer 10

Responsible for variation in length of someone’s phase

-Begins at menstruation, there is oestrogen driven growth of endometrial glands and stroma

Question 11

Day 15-28 known as?

Answer 11

Secretory phase

Question 12

What happens in secretory phase?

Answer 12

Progesterone induced glandular secretory activity, decidualization, then endometrial apoptosis and subsequent menstruation

Question 13

What is decidualization?

Answer 13

Changes to cells for preparation of pregnancy

Question 14

What stimulates FSH and LH release and from where?

Answer 14

Pulses of GnRH at about 2 hour intervals

-From anterior pituitary

Question 15

What does LH stimulate?

Answer 15

Theca cells to produce androgens

Question 16

What does FSH stimulate?

Answer 16

Growth of ovarian follicles and associated rise in FSH via negative feedback

Question 17

What happens when oestrogen reaches a ~certain~ concentration level?

Answer 17

Exerts positive feedback resulting in an increase in FSH and LH surge

Question 18

What hormone causes ovulation and regulates formation of corpus luteum?

Answer 18

LH

Question 19

What does corpus luteum do?

Answer 19

Secretes progesterone and oestrogen so FSH and LH fall due to negative feedback on GnRH pulsatility

Question 20

Fall in progesterone results in?

Answer 20

Increased GnRH and FSH (cycle can begin again)

Question 21

Granulosa cells produce?

Answer 21

Oestrogens & progesterone

Question 22

Thecal cells produce?

Answer 22

Ovarian androgens when stimulated by

LH