CH 8 Male Reproductive Sys

Question 1

Where are Sertoli Cells located?

Answer 1

Seminiferous tubules

Question 2

Tract sperm from Sertoli Cells to Vas Deferens.

Answer 2

Sertoli Cells in seminiferous tubules –> rete testis –> efferent ductules –> epididymis –> vas deferens

Question 3

What cells are responsible for secreting Testosterone?

Answer 3

Leydig cells

Question 4

What are the functions of Sertoli Cells?

Answer 4

form blood-testes barrier, signal spermatogenesis, produce inhibin B

Question 5

What does the Epididymis do?

Answer 5

H+ secretion & acidification of luminal fluid

Question 6

What do the Seminal Vesicles do?

Answer 6

secretion and storage of fructose-rich product

Question 7

What does the Prostate do?

Answer 7

secretes acid proteins

Question 8

What do the Bulbourethral glands do? (Cowper’s)

Answer 8

secrete mucus upon arousal

Question 9

What cell does LH bind to?

Answer 9

Leydig Cells

Question 10

What cell does FSH bind to?

Answer 10

Sertoli Cells

Question 11

What stimulates inhibin B release?

Answer 11

FSH on Sertoli Cells

Question 12

What receptor does Testosterone bind to?

Answer 12

Androgen Receptor AR

Question 13

What substances and Testosterone be converted to? What are their effects?

Answer 13

dihydroxytestosterone DHT (most potent androgen) or 17B-estradiol (inhibitory effects on LH)

Question 14

What does Inhibin B do?

Answer 14

negative feedback response to FSH stimulation from Sertoli Cells

Question 15

What does Activin do?

Answer 15

produced locally by pituitary to stimulate FSH release (counteracts inhibin B)

Question 16

What enzyme converts androsetenedione to testosterone?

Answer 16

17-beta-hydroxysteroid dehydrogenase

Question 17

What enzyme converts Testosterone to 17-B-extradiol

Answer 17

Aromatase (mainly in adipose tissue)

Question 18

What step of Testosterone synthesis is exclusive to the Gonads?

Answer 18

Androstenedione –> Testosterone (17-B-hydroxysteroid dehydrogenase)

Question 19

Why would Inhibin B levels be clinically evaluated?

Answer 19

it correlates to total sperm count - evaluated as an index of spermatogenesis

Question 20

What are the binding proteins for testosterone? where are they found?

Answer 20

sex hormone-binding globulin SHBG (circulation); androgen-binding protein ABP (testis)

Question 21

How is testosterone degraded?

Answer 21

testosterone –> androstenedione –> 17-ketosteroid

Question 22

How is 17B-estradiol degraded?

Answer 22

17B-estradiol –> esterone –> catecholesterogens (degraded by COMT) or 16-alpha-hydroxyesterone (converted to estriol)

Question 23

What enzyme converts testosterone to DHT?

Answer 23

5alpha-reductase (type 1 & type 2, which generates more DHT than type 1)

Question 24

How is DHT degraded?

Answer 24

3-alpha-androstenediol (via 3alpha-hydroxysteroid dehydrogenase)

Question 25

What is Finasteride used for?

Answer 25

treatment of benign prostatic hyperplasia and prostate cancer (5alpha-reductase inhibitor -- can't form DHT)

Question 26

How does testosterone differ from DHT?

Answer 26

testosterone controls sexual differentiation, libido, pubertal growth, and stimulation of spermatogenesis. DHT plays a major role in embryonic and pubertal external virilization (development of external genitalia, pubic hair, etc)

Question 27

How does differentiation into a male occur?

Answer 27

SRY gene signals differentiation of primordial cells to Sertoli Cells, which secrete Mullerian Inhibitory Factor, causing Wolffian Duct to proliferate. DHT causes growth of prostate and penis and fusion of labioscrotal folds. Leydig Cells secrete Insulin-like peptide 3 INSL3, which participates in testicular descent.

Question 28

What are the 3 steps of development of male phenotype?

Answer 28

determination of genetic sex, gonadal sex, and lastly, phenotypical sex

Question 29

Why is cryptorchidism important?

Answer 29

cryptorchidism (descent of scrotum) is important because spermatogenesis requires lower temperatures

Question 30

How does Leptin affect growth?

Answer 30

Increase in amplitude of GnRH pulses and amplitude of GH secretory bursts.

Question 31

What hormone stimulates spermatogenesis?

Answer 31

Testosterone

Question 32

How does testosterone effect adipocytes?

Answer 32

stimulates lipylosis

Question 33

How does Hypergonadism work? (testosterone)

Answer 33

premature virilization (can be gonadotropin dependent or independent) - enlargements of penis and testicles, body hair, spontaneous erections, acne

Question 34

How does Hypogonadism work? (testosterone)

Answer 34

decrease in bone and muscle mass (weakness), and libido in adults, appear more female-like

Question 35

Klinefelter syndrome

Answer 35

additional X chromosome - results in male infertility, hypogonadism, androgen deficiency, and impaired spermatogenesis

Question 36

How does hyperprolactinemia effect males?

Answer 36

prolactin inhibits GnRH -- hopygonadotropic hypogonadism