Male Reproductive Physiology

Question 1

Leydig Cell Functions

Answer 1

Synthesize and Secrete Testosterone
Make Cholesterol
Make DHT and Estradiol

Question 2

Sertoli Cell Functions

Answer 2

Provide nutrients for spermatogenesis
Form blood-testis barrier
Produce aromatase and Estrogen
Produce ABP
Produce inhibins

Question 3

Hypothalamic-Pituitary Axis

Gonadotropin Regulation

Answer 3

Androgens/Estrogen decrease GnRH from hypothalamus
Androgens/Estrogen decrease LH from AP
Inhibin decreases FSH from AP

GnRH increases LH and FSH from AP

Question 4

Spermatogenesis Hormonal Regulation

Answer 4

GH stimulates early division
FSH stimulates Meiosis I
LH stimulates Leydig cells
Testosterone Stimulates Meiosis II

Question 5

Spermatogenesis Steps and Location

Answer 5

1) Spermatogonium undergoes mitosis to make 2n, 2D spermatogonia
2) Spermatogonia undergo Meiosis I to make 1n, 2D spermatocytes, spermatocytes undergo Meiosis II to make 1n, 1D spermatids
3) Spermatids undergo spermiogenesis and become spermatozoa

All of this happens in Seminiferous Tubules

Question 6

Steroidogenesis

Hormones, Enzymes, Cell Producing

Answer 6

Testosterone made in Leydig cells via 17-Beta Hydroxysteroid Dehydrogenase

Androstenedione made in Leydig cells via 3-Beta Hydroxysteroid Dehydrogenase

DHT made in Leydig cell but mostly in periphery via 5-Alpha Reductase

Estrogen made in Sertoli cell via aromatase

Question 7

GnRH Actions

Answer 7

Pulsatile secretion initiates puberty via LH/FSH

Question 8

LH Actions

Answer 8

Stimulate pregnenolone synthesis via desmolase

Increases testosterone production in Leydig cells

Question 9

FSH Actions

Answer 9

Stimulates Inhibin production
Stimulates ABP production
Stimulates aromatase production
Stimulates Sertoli cells to make growth factors

Question 10

Testosterone Actions

Answer 10

Causes male internal genitalia formation
Increases muscle mass
Increases body/penis/seminal vesicle growth
Closes epiphyseal plates
Stimulates spermatogenesis

Question 11

DHT Actions

Answer 11

Male external genitalia formation
Hair distribution/baldness
Sebaceous gland activity
Prostate growth

Question 12

Inhibin Actions

Answer 12

Decreases FSH release

Question 13

AMH Actions

Answer 13

Causes regression of Paramesonephric (Mullerian) duct to stop female genitalia formation

Question 14

Androgen Negative Feedback

Answer 14

Mostly from Testosterone and Estradiol

Some from DHT

Question 15

Erection Biochemical Cascade

Answer 15

PSNS releases NO which activates guanalyl cyclase
cGMP is increased which decreases Calcium
Smooth muscle relaxes and vasodilation increases blood flow to erectile tissue

Question 16

Kallman’s Syndrome

Dysfunction and Effects

Answer 16

GnRH neurons don’t develop
Causes decreased GnRH, LH, FSH and Testosterone

Leads to delayed/absent puberty, inability to smell and hypogonadism

Question 17

Klinefelter Syndrome

Dysfunction and Effects

Answer 17

Male with two X chromosomes
Causes increased gonadotropins but decreased testosterone

Leads to phenotypically male person with primary hypogonadism causing infertility

Question 18

Sildenafil Actions

Answer 18

Viagra is a PDE inhibitor which blocks the conversion of cGMP to GMP to prolong erection

Question 19

Benign Prostatic Hyperplasia

Symptoms, Potential Cause, Treatment

Answer 19

Increased urination and dribbling
Decreased emptying
Dysuria and nocturia

May be caused by increased DHT receptors
Treat with 5-Alpha Reductase inhibitor