Male Reproductive System

Question 1

Male reproductive hormone synthesised in the preoptic nucleus of hypothalamus?

Answer 1

GnRH

Question 2

Function of GnRH?

Answer 2

Stimulation of gondotrophs in anterior pituitary-release of FSH, LH

Question 3

Male reproductive hormones secreted in anterior pituitary?

Answer 3

FSH and LH

Question 4

Source of FSH and LH?

Answer 4

Gonadotrophs of anterior pituitary

Question 5

What factor differentiates TSH, LH, hCG, FSH synthesis?

Answer 5

Beta subunit; alpha subunit

Question 6

Hormones that are glycoproteins?

Answer 6

LH, FSH, hCG, TSH

Question 7

Site of action of LH?

Answer 7

Leydig cells in interstitium of testis

Question 8

Function of LH?

Answer 8

Production of a regulatory protein-stimulation of formation of testosterone and DHT in leydig cells

Question 9

Site of action of FSH?

Answer 9

Sertoli cell

Question 10

Function of FSH?

Answer 10

1. Stimulates secretion of androgen binding protein in Sertoli cell;
2. growth factors
3. Stimulates synthesis of mullerian inhibiting factor by Sertoli cells;
4. Stimulation of inhibin release;
5. and aromatase–>T->estradiol

Question 11

What factor is required for negative feedback regulation of FSH vs. LH?

Answer 11

FSH-inhibin

LH-testosterone

Question 12

How does testosterone regulate HPG axis?

Answer 12

Negative feedback of LH from pituitary

Question 13

How does inhibin regulate HPG axis?

Answer 13

Negative feedback inhibition of FSH

Question 14

Circulating form of testosterone in blood?

Answer 14

Bound to protein (globulin)

Question 15

Potent form of testosterone?

Answer 15

DHT

Question 16

Enzyme required for conversion of testosterone to DHT?

Answer 16

5 alpha reductase

Question 17

Function of 5 alpha reductase?

Answer 17

Conversion of testosterone to DHT (more potent form)

Question 18

Functions of DHT?

Answer 18

Development of male external genitalia;

Prostate enlargement;

Male pattern baldness;

NO synthase formation in penile tissue

Question 19

Hormone required for erection?

Answer 19

DHT; formation of nitric oxide synthase that synthesises NO for relaxation of penile tissue

Question 20

Hormone involved in growth of prostate?

Answer 20

DHT

Question 21

Hormone responsible for increased activity of sebaceous glands in males?

Answer 21

DHT

Question 22

Function of aromatase in Sertoli cells?

Answer 22

Conversion of testosterone to estradiol required for growth and maturation of sperm

Question 23

Conversion of testosterone to estradiol in Sertoli cells is stimulated by?

Answer 23

Aromatase

Question 24

Hormone required for aromatase stimulation?

Answer 24

FSH

Question 25

Hormones required for production of growth factors in Sertoli cells?

Answer 25

FSH and testosterone

Question 26

Hormones required for maintenance of high local levels of testosterone in Sertoli cells?

Answer 26

Testosterone and FSH

Question 27

Types of adrenal androgens?

Answer 27

DHEA and androstenedione

Question 28

Potency of androgens in increasing order: testosterone, DHT and adrenal androgens?

Answer 28

Adrenal androgens

Question 29

Sites of aromatase enzyme production in males?

Answer 29

Adipose cells-> peripheral conversion Sertolic cells->growth and maturation of sperms

Question 30

Ages during which testosterone and LH levels are high?

Answer 30

Fetal life and adulthood

Question 31

Ages during which testosterone and LH are low?

Answer 31

Childhood and ageing adult (only testosterone is low)

Question 32

Changes in LH and testosterone during puberty?

Answer 32

Increased amplitude of LH pulses (during sleep) -> increased LH; increasing testosterone

Question 33

Changes in LH and Testosterone during childhood?

Answer 33

Low levels of both

Question 34

Changes in LH and testosterone during adulthood?

Answer 34

Increased LH secretion drives testosterone secretion

Question 35

Changes in LH and Testosterone in an ageing adult?

Answer 35

Testosterone production decrease; LH production remains high due to loss of feedback inhibition

Question 36

Effect of androgens on muscle mass?

Answer 36

Increased; decreased breakdown of protein and increased synthesis of protein

Question 37

Cause of infertility in cryptorchid testes?

Answer 37

Spermatogenesis is temperature dependant; ceases at temperatures of abdominal cavity

Question 38

Cooling mechanism of testes?

Answer 38

1. Countercurrent heat exchanger in spermatic cord | 2. Contraction/ relaxation of cremastric muscle and scrotal skin rugae

Question 39

Effect on FSH and LH in cryptorchid testes?

Answer 39

Elevated

Question 40

Cause of elevated FSH and LH in cryptorchid testes?

Answer 40

Cryptorchid testes-> temperature elevated-> dysfunction of Sertoli and leydig cells-> loss of inhibition to FSH and LH

Question 41

Consequence of testosterone deficiency in 2nd -3rd month of gestation?

Answer 41

Male pseudointersexuality/ambiguity in male genitalia

Question 42

Consequence of testosterone deficiency in 3rd trimester?

Answer 42

Cryptorchidism and micropenis

Question 43

Consequence of testosterone deficiency in puberty?

Answer 43

Lacking male external genitalia

Question 44

Consequence of testosterone deficiency in post pubertal age?

Answer 44

Decreased libido, erectile dysfunction, decrease in facial and body growth hair, low energy and infertility

Question 45

Age of testosterone deficiency if varying degrees of ambiguity in male external genitalia/male pseudointersexuality?

Answer 45

1st trimester

Question 46

Age of testosterone deficiency if micropenis and Cryptorchidism present?

Answer 46

3rd trimester

Question 47

Age of testosterone deficiency if male external genitalia lacking?

Answer 47

Pubertal testosterone deficiency

Question 48

Age of testosterone deficiency if decreased libido, erectile dysfunction, decreased facial and body hair and low energy?

Answer 48

Post pubertal

Question 49

Location of synthesis of GnRH?

Answer 49

Preoptic nucleus of hypothalamus