Repro Phys I

Question 1

Function of ovarian cortex and ovarian medulla

Answer 1

Cortex = where oocytes and corpus luteum develop
Medulla = inner stroma with large vasculature

Question 2

HPG/HPO axis

Answer 2

Hypthalamus releases GnRH –> ant pituitary releases FSH and LH (similar structure to TSH) –> LH binds theca cells to make androstenedione and FSH binds granulosa cells to make estrogen and ovarian peptides

Question 3

GnRH pulsatility before and after puberty

Answer 3

Constant/non-pulsatile before puberty
Pulsatile beings in puberty

Question 4

When is GnRH sensitivity highest in life?

Answer 4

During childhood/before puberty (little amount of sex steroid can act as negative feedback to the hypothalamus and anterior pituitary, pulsatility later in life decreases sensitivity of HPG axis to sex steroids)

Question 5

End results of FSH and LH release

Answer 5

Follicular development
Steroidogenesis (Estrogen, progesterone)
Luteinization
Ovulation

Question 6

What secondary sex characteristics does GnRH pulsatile release result in?

Answer 6

Thelarche (breast development)
Menarche
Adrenarche

Question 7

How does menarche occur?

Answer 7

Increase in GnRH pulsatility until it results in a sufficient LH surge to initiate the first menstrual cycle

Question 8

T or F: F HPG axis has variability in how it responds to its end products

Answer 8

T – early in the follicular phase estrogen is (-) feedback, but in the late follicular phase it acts as (+) feedback to initiate LH surge

Question 9

What time of day is pulsatility most prevalent in puberty?

Answer 9

Night/early hours of REM sleep (constant pulsatility during reproductive years)

Question 10

What are the levels of FSH and LH in early menopause?

Answer 10

High because the ovaries are not responding with more estrogen production, so the pituitary releases more FSH and LH in an attempt to increase estrogen levels

Question 11

What decreases the HPG’s sensitivity to sex steroids?

Answer 11

GnRH pulsatility

Question 12

What are the ovarian peptides?

Answer 12

Inhibins and activins

Question 13

Which cells produce ovarian peptides?

Answer 13

Granulosa cells

Question 14

What determines whether granulosa cells make inhibins or activins?

Answer 14

Stage of menstrual cycle

Early follicular phase = negative feedback state –> make activins to promote FSH release and prevent LH surge

Late follicular phase = positive feedback state –> make inhibins to prevent FSH release and activate the LH surge

Question 15

What do inhibins do?

Answer 15

Act on the anterior pituitary to decrease FSH release (therefore increasing LH release

Question 16

What do activins do?

Answer 16

Promote FSH release from anterior pituitary and stimulate FSH receptors on granulosa cells

Question 17

What inhibits inhibin release?

Answer 17

Estradiol/estrogens

Question 18

What promotes the LH surge?

Answer 18

High estrogen and inhibins

Question 19

Is the majority of the menstrual cycle under positive or negative feedback

Answer 19

Negative – leads to a decline in both LH AND FSH

Question 20

Estrogen levels rise in late follicular phase, leading to…

Answer 20

switch of HPG axis to positive feedback, estrogen and high inhibins work together to create LH surge and ovulation (day 14)

Question 21

Theca cell qualities

Answer 21

Superficial
No aromatase – can’t make estrogen
Only have LH receptors
Able to uptake LDL from blood and make pregnenolone

Question 22

Granulosa cell qualities

Answer 22

Deeper
Aromatase activity – CAN make estrogens
No 17alpha-hydroxylase acitvity – CANT make androgens
Able to uptake LDL from blood or use de novo synthesis
and make pregnenolone
Both LH and FSH receptors

Question 23

How do increasing androgen levels affect aromatase activity?

Answer 23

Inhibits aromatase activity bc the androgens promote DHT production

Question 24

How does decreased aromatase activity affect LH receptor expression?

Answer 24

Decreased LH receptor expression, which decreases estrogen production

Question 25

What is the function of 17alpha-hydroxylase

Answer 25

Allows formation of hydroxypregnenolone and progesterone from pregnenolone

Question 26

Which cells can make progesterone?

Answer 26

Both theca and granulosa

Question 27

Which cells make androgens?

Answer 27

Theca cells

Question 28

Which cells make estrogen?

Answer 28

Granulosa cells (androgens from theca cells diffuse into the granulosa cells)