Reproductive Endocrinology

Question 1

What are the three sources of sex steroids?

Answer 1

1. Adrenal cortex
2. Placenta
3. Gonads

Question 2

What are the three major classes of sex steroids?

Answer 2

1. Pregnanes (21C)
2. Androgens/Androstanes (19C)
3. Estrogens/estranes (18C)

Question 3

The primary male hormone is ______ which is an ________.

Answer 3

testosterone; androgen

Question 4

Testosterone is converted to the most potent androgen _____, by the enzyme 5alpha-reductase.

Answer 4

DHT

Question 5

The two most important female hormones are ________ and _______.

Answer 5

progesterone; estradiol

Question 6

Estradiol is an estrogen produced from _______ bu the enzyme aromatase.

Answer 6

testosterone

Question 7

T/F: Sex steroids can be stored in the cell.

Answer 7

FALSE

Steroids are lipophilic hormones and cannot be stored

Question 8

What is the reproductive axis?

Answer 8

Hypothalamus -> anterior pituitary -> Gonads

Question 9

T/F: When stimulated, there is a constant flow of GnRH from the hypothalamus.

Answer 9

FALSE

Pulsating

Question 10

Bursts of GnRH from the hypothalamus cause what response from the anterior pituitary?

Answer 10

Pulsating release of LH and FSH

Question 11

If GnRH is received in the anterior pituitary in a constant fashion what will its response be?

Answer 11

Inhibit LH and FSH secretion

Question 12

Gonadal steroids exert negative feedback control of GnRH and LH secretion, except in which case?

Answer 12

Estradiol has a positive feedback on LH prior to ovulation in females

Question 13

In the gonads, which genes are transcribed by the steroid/receptor complex?

Answer 13

Genes regulating gametogenesis and hormone synthesis

Question 14

What is a secondary effect of gonadal steroids?

Answer 14

Regulate protein synthesis in other reproductive organs (male accessory glands, uterus, breasts, brain)

Question 15

Spermatic cells include _______ active spermatogonia and ______ spermatocytes.

Answer 15

mitotically; meiotic

Question 16

________ cells synthesize testosterone in response to LH.

Answer 16

Leydig

Question 17

Testosterone regulates sexual behavior after what?

Answer 17

After being aromatized to estradiol

Question 18

What is the role of Sertoli cells?

Answer 18

Respond to FSH to regulate spermatogenesis and produce inhibin

Question 19

_______ has negative feedback actions on FSH secretion.

Answer 19

Inhibin

Question 20

What cells make up the epithelial lining of the seminiferous tubules?

Answer 20

Sertoli cells

Question 21

In the testes, _______ cells respond to FSH; _______ cells respond to LH

Answer 21

Sertoli; Leydig

Question 22

What are some effects of T that are important for women?

Answer 22

1. Regulate bone growth
2. Stimulate muscle growth
3. Stimulate erythropoiesis

Question 23

How is male pattern baldness treated?

Answer 23

5alpha-reductase inhibitors to decrease T -> DHT

DHT thought to be major contributor to baldness

Question 24

T/F: As T decreases with age, most men become sterile.

Answer 24

FALSE

T does decrease, but most men remain fertile

Question 25

______ cells surround each follicle and are similar in function to Leydig cells.

Answer 25

Theca

Question 26

The _______ cells are the epithelial cells of the follicle.

Answer 26

Granulosa

Question 27

_______ cells are present after ovulation, when the theca and granulosa cells are transformed into the cells of the corpus luteum.

Answer 27

Luteal

Question 28

Theca cells respond to ___; while granulosa cells respond to ____.

Answer 28

LH; FSH

Question 29

What hormone do Theca cells sythesize?

Answer 29

Androstenedione

Question 30

Where does androstenedione go once synthesized?

Answer 30

Diffuses into granulosa cells and some into systemic circulation

Question 31

What happens to androstendione in the granulosa cell?

Answer 31

Androstenedione -> estrone -> estradiol

Question 32

What are the functions of estradiol secreted by the granulosa cells?

Answer 32

1. Regulate oocyte development 2. Regulate secondary sex characteristics 3. Regulate bone turnover and arterial function 4. Inhibits GnRH and LH secretion

Question 33

Along with estradiol, what else is secreted by the granulosa cell?

Answer 33

Inhibin: negative feedback on FSH

Question 34

Describe the ovarian cycle.

Answer 34

1. Gonadotropin rise and follicle develops 2. Increase E2 and inhibin 3. FSH decrease (via inhibin increase); E2 peak -> LH surge 4. Meiosis I complete, ovulation, CL formation 5. Increase E2 and P -> inhibit LH and FSH 6. CL regression, decrease steroids, LH/FSH rise

Question 35

If pregnancy were to occur, the placenta produces ____.

Answer 35

hCG

Question 36

What are the hormonal consequences of menopause?

Answer 36

1. Lose ovarian steroids 2. Gonadotropin and inhibin secretion very high 3. Increase reliance on adrenal steroids

Question 37

Which gene on the Y chromosome directs the indifferent gonad to become a testis?

Answer 37

SRY

Question 38

What two hormones regulate sexual differentiation of the internal genitalia in males?

Answer 38

Testosterone and Mullerian inhibiting substance (MIS)

Question 39

What are the roles of T and MIS in developing males?

Answer 39

T: stimulates Wolffian duct system which will become tubules of reproductive tract MIS: causes Mullerian duct system to regress

Question 40

What gonadal steroids are stimulated in the developing female?

Answer 40

None. Absence of T causes Wolffian duct to regress. Absence of MIS causes proliferation of Mullerian duct system.

Question 41

What hormone stimulates male external genitalia differentiation?

Answer 41

Adrogens: T -> DHT

Question 42

What would happen to a developing male with a 5alpha-reductase deficiency?

Answer 42

Less DHT would be developed during development -> no differentiation of external genitalia Increased T at puberty would complete differentiation

Question 43

Does Congenital adrenal hyperplasia cause problems in developing men or women?

Answer 43

Women. Not enough enzyme -> excess androgens. Women will have male looking external genitalia

Question 44

What is the result of an androgen insensitivity?

Answer 44

No functional androgen receptor -> T and DHT cannot function. Leads to XY genotype, but female phenotype

Question 45

During pregnancy, placental ____ stimulates growth of myometrium, and ____ reduces uterine contractility and stimulates vasodilation.

Answer 45

E2; P