Male and Female Gonad Physiology

Question 1

Which cells in the testes produce testosterone and how is it regulated?

Answer 1

Leydig cells and regulated LH via pituitary, and GnRH via hypothalamus (mediated by the chemical from the conversion of T to E2)
T in pituitary inhibits the synthesis of LH-beta subunit

Inhibin and activin locally regulates GnRH

Question 2

Which hormones are measured to assess male gonadal failure?

Answer 2

Testosterone and LH

Question 3

Describe the hormonal levels in primary testicular failure:

Answer 3

low T, high LH

Question 4

Describe the hormone levels in pituitary failure:

Answer 4

low T, low LH

Question 5

Which cells and hormone help in spermatogenesis?

Answer 5

Sertoli cells and FSH

Question 6

What condition is necessary for spermatogenesis to occur?

Answer 6

high intratesticular levels of testosterone

Question 7

Which cells make inhibin b?

Answer 7

Sertoli Cells

Question 8

What can a small testes mean from a physical exam?

Answer 8

loss of seminiferous tubules or leydig cells

Question 9

How does prolactin interact with the male repro system?

Answer 9

Increased prolactin inhibits LH/FSH release, leading to low testosterone/sperm production

Question 10

What is the condition when LH is high, FSH is low, and T is low, and small testes?

Answer 10

Fertile eunuch syndrome (eventually will lead to complete testicular failure)

Question 11

What forms of testosterone is bioavailable?

Answer 11

Albumin-bound, and free floating

SHBG-bound not active for use

Question 12

True or false obesity affects obesity decreases SHBG and may erroneously indicate hypogonadism ?

Answer 12

True

Question 13

What kind of serum testosterone should be measured in obese people?

Answer 13

bioavailable T (albumin and free) or free T

Question 14

True or False: free Testosterone levels change with changes in protein bound T

Answer 14

False

Question 15

Which cells in the ovaries convert cholesterol to create testosterone and intermediates for estrogen?

Answer 15

Theca Cells

Question 16

What cells in the ovaries produce estrogen (estradiol)?

Answer 16

Granulosa cells

Question 17

True or False corpus luteum produces progesterone

Answer 17

True

Question 18

List the steps and hormones involved leading to ovulation:

Answer 18

Cohort of secondary follicles recruited – initiated by rise in FSH + loss of negative feedback to gonadal steroids and inhibin A

Selection of one dominant follicle –rising E2 and inhibin A (from follicle) restrain FSH rise so only one follicle develops

Further growth dominant follicle: E2, inhibin A increase exponentially, follicle acquires LH receptors

Exponential rise in E2 triggers POSITIVE FEEDBACK in hypothalamus leading to LH (and FSH) surge, triggering ovulation and luteinization of granulosa cells

Question 19

What are the effects of progesterone on other hormones?

Answer 19

inhibits GnRH, LH, and FSH production and maintains the endometrium (by making glandular and vascular and secreting nutritious fluid for embryonic development)

Question 20

How does is the endometrium maintained after egg is fertilized?

Answer 20

blastocyst/trophoblast secretes hCG which binds to LH receptors in corpus luteum, stimulating progesterone and E2 secretion
These maintain the endometrium until implantation and placenta takes over hormone production

Question 21

What is tbe hormonal feature of menopause?

Answer 21

high FSH and low E2