Lect 2: Male Repro

Question 1

Full development and function of the seminiferous tubules require

Answer 1

androgens and FSH

Question 2

In human males testosterone is produced mainly by

Answer 2

Leydig cells

Question 3

Nitrous oxide synthase contributes to erection by

Answer 3

activating soluble guanylate cyclases to increase cGMP levels that relax smooth muscle and increase blood flow

Question 4

Testosterone is produced

Answer 4

in Leydig cells from cholesterol and pregnenalone precursors

Question 5

The pubertal growth spurt is stimulated by the hormone

Answer 5

estradiol

Question 6

The hormone inhibin has direct negative feedback effects on the release of

Answer 6

FSH

Question 7

a 16 y/o girl suffers from 5alpha-reductase deficiency. The individual was raised as a male but at puberty secondary sex characteristics and male growth occurred. Levels of which steroid is reduced during puberty?

Answer 7

DHT

Question 8

A 55 y/o man complains of reduced libido and muscle strength. Serum analysis showed reduced levels of testosterone. Reduced activity in which hormone–target axis is causing the symptoms?

Answer 8

Leuteinizing hormone (LH)–Leydig cell

Question 9

In order for male differentiation to occur during development testosterone must be secreted from the testes. WHich hormone stimulates the secretion of testosterone?

Answer 9

hCG

Human chorionic gonadotropin also binds to luteinizing hormone receptors on the interstitial cells of the testes of the male fetus, resulting in the production of testosterone in male fetuses up to the time of birth. This small secretion or testosterone is what causes the fetus to develop male sex organs instead of female sex organs.

Question 10

A man is taking lots of med, one of which is interfering with the emission phase of sex. Which med is causing this?

Answer 10

inhibitor of sympathetic nervous system receptor

Feedback:

Emission is elicited by reflexes mediated by the sympathetic nervous system. Beta adrenergic antagonists interfere with the reflex. None of the other choices is involved.

Question 11

Men who take large doses of testosterone-like androgenic steroids are sterile in the reproductive sense of the word. Why?

Answer 11

High levels of androgen compounds inhibit the secretion of gonadotropin-releasing hormone by the hypothalamus, resulting in the inhibition of luteinizing hormone and follicle-stimulating hormone release by the anterior pituitary.

Testosterone secreted by the testes in response to luteinizing hormone (LH) inhibits hypothalamic secretion of gonadotropin-releasing hormone (GnRH), thereby inhibiting anterior pituitary secretion of LH and follicle-stimulating hormone. Taking large doses of testosterone-like steroids also suppresses the secretion of GnRH and the pituitary gonadotropic hormones, resulting in sterility