General overview of reproductive axis

Question 1

1. Recognize the cholesterol molecule and correctly number the carbon atoms in the steroid nucleus.

Answer 1

27 carbons

Question 2

2. List the molecules synthesized from cholesterol throughout the body, including examples from each of the three major classes of steroid hormones and the three major classes of sex steroids.

Answer 2

glucocorticoids, mineralocorticoids, sex steoids

sex steroids- androgens, progestins, estrogens

Question 3

3. Describe key features in the biosynthesis of the sex steroids and describe the rate-limiting step.

Answer 3

rate limiting step is the mitochondrial side chain cleavage enzyme 20-22 desmolase which cuts off the tail to become pregnenalone

Question 4

4. List the endogenous sex steroids and classify them into the three major classes of sex steroids on the basis of the number of carbon atoms they contain.

Answer 4

progestins C21
Androgens C19
Estrogens- C-18

Question 5

5. Name the hormones involved in the hypothalamic - pituitary - gonadal axis and label them on a diagram of that axis.

Answer 5

GnRH-+ FSH, LH

FSH- sertoli and granulosa cells
LH- Leydig and theca cells (granulosa cells)

testosterone- feedback on pituitary and hypo
estradiol- feedback on pituitary and hypo
progesterone- feedback on pituitary and hypo

Inhibin- feedback on pituitary only

at mid cycle of ovulatory women ovarian estradiol also exerts positive feedback on the pituitary gland

Question 6

6. List the primary areas of the hypothalamus responsible for the production of GnRH and describe key features of hypothalamic GnRH secretion.

Answer 6

arcuate nucleus and preoptic area- released in pulsatile fashion in men (constant)
women the pulsatile fashion changes during the menstrual cycle

released in portal circulation

Question 7

7. Describe the structure, functions and mechanisms of action of the hormones involved in the hypothalamic - pituitary - gonadal axis in both men and women.

Answer 7

1

Question 8

8. Describe the 2-cell theory of sex steroid production and name the gonadal cells responsible for the production of sex steroids in men and women.

Answer 8

sertoli and granulosa cells both are adjacent to developing gametes have FSH receptors can make inhibin and can convert androgens to estrogens due to aromatase

leydig and theca cells have LH receptors can make androgens but can not make estrogens

Question 9

9. List the major extra-gonadal sources of various sex steroids.

Answer 9

placenta, adrenal cortex, skin, adipose tissue

Question 10

10. Compare and contrast features of the normal hypothalamic-pituitary-gonadal axis in men and women.

Answer 10

1

Question 11

11. Label a diagram of the ovarian/menstrual cycle and describe how disruptions of the hypothalamic-pituitary-ovarian axis can lead to irregular periods in women.

Answer 11

1

Question 12

12. Frame discussions of the physiology, pathophysiology, and pharmacology of the reproductive system in terms of the hypothalamic-pituitary-gonadal axis.

Answer 12

1

Question 13

progestins

Answer 13

testes

Question 14

E1

Answer 14

adipose

Question 15

E2

Answer 15

gametogenesis
prepares uterus for conception (progesterone specifically)
breast development to support lactation

Question 16

E3

Answer 16

placenta

Question 17

DHEA

Answer 17

adrenal same for M and F 10^-8

Question 18

DHEA sulfate

Answer 18

adrenal

Question 19

DHtesosterone

Answer 19

skin

Question 20

testosterone

Answer 20

M 95% testes 5% adrenal,
F 50%ovaries, 50%adrenal

anabolic- bone growth muscle growth
androgenic- gametogenesis, secondary sex characterisitcs, libido, puberty