Introduction to the Reproductive System: Physiology and Biochemistry

Question 1

The conversion of _______________ is the rate-limiting step in sex-hormone synthesis.

Answer 1

cholesterol to pregnenolone (by 20,22-desmolase)

Question 2

Progestins are _______ carbons and androgens are _______ carbons.

Answer 2

21; 19

Question 3

How many carbons are in estrogen?

Answer 3

18

Question 4

What effects do androgens have?

Answer 4

Bone and muscle: growth
Skin: sebum production
Testes: spermatogenesis
Brain: libido

Question 5

The main tissues with progesterone receptors are ___________.

Answer 5

uterus, ovaries, breast

Question 6

What part of the hypothalamus releases GnRH?

Answer 6

Arcuate nucleus and pre-optic area

Question 7

LH acts on ________.

Answer 7

Leydig cells, which release androgens

Question 8

FSH acts on ___________.

Answer 8

Sertoli cells, which releases aromatase, inhibin, and growth factors on the Leydig cells

Question 9

Testosterone has a negative feedback on the ______________.

Answer 9

hypothalamus and pituitary

Question 10

The positive feedback of ___________ causes the surge of LH.

Answer 10

progesterone

Question 11

The secretion of HCG during pregnancy causes lower levels of TSH. Why?

Answer 11

Because it has a homologous skeleton (the AA subunits)

Question 12

Most male testosterone is produced in the ________.

Answer 12

testes (by Leydig cells)

Question 13

Most dihydrotestosterone is produced in the _____________.

Answer 13

body’s periphery

Question 14

Androgens are converted to estrogens by ____________.

Answer 14

aromatase

Question 15

In males, Sertoli cells produce __________.

Answer 15

estrogen

Question 16

In females, which cells produce estrogen?

Answer 16

Granulosa cells of the ovary

Question 17

Inhibin exerts negative feedback on the ______________.

Answer 17

pituitary

Question 18

What happens at midcycle in women?

Answer 18

Estradiol becomes a positive feedback and stimulates a surge of LH and FSH

Question 19

In females, the Leydig cells are called ________. Both have LH receptors and cannot make estrogen.

Answer 19

theca

Question 20

How are Sertoli and granulosa cells similar?

Answer 20

Both have FSH receptors, aromatase, and make inhibin

Question 21

Testosterone works on __________ to stimulate spermatogenesis.

Answer 21

Sertoli cells

Question 22

Theca cells produce ____________ which goes to granulosa cells to become ____________.

Answer 22

androstenedione; estradiol