Male Reproductive System II

Question 1

What gonadotropins regulate gametogenesis and gonadal steroidogenesis?

Answer 1

Follicle stimulating hormone

Luteinizing hormone

Question 2

What will happen as a result of continuous exposure to GnRH?

Answer 2

Suppression of gonadotrope secretory activity

Functional Castration

Question 3

Describe the HPG axis during fetal development

Answer 3

Established during the firs trimester

Activity peaks mid-gestation and declines towards birth due to negative feedback of placental estrogens

Question 4

Describe the HPG axis during the neonatal period

Answer 4

HPG axis becomes active again

Gonadotropin levels are elevated then decline as CNS gradually exerts an inhibitory effect on the HPG

Question 5

Describe the HPG axis during childhood

Answer 5

Comes under the control of CNS neurons that exert a strong inhibitory effect

HPA axis remains relatively quiescent during childhood

Question 6

Describe the HPG axis during the lat prepubertal period?

Answer 6

Gradual disinhibition

First detectable change in goandotropin production is a sleep-associated surge in LG release

Question 7

Describe the HPG axis during puberty?

Answer 7

HPG becomes increasingly active

Adult patter of HPG activity is established

Question 8

What are the major events associated with puberty?

Answer 8

Establishment of HPG activity

Maturation of reproductive system and development of secondary sexual characteristics

Pubertal growth spurt

Gametes capable of fertilization

Question 9

What is the feedback effect of testosterone?

Answer 9

Testosterone inhibits the hypothalamic pulse generator

Question 10

What is the feedback effect of Inhibin?

Answer 10

Secreted by sertoli cells

Inhibits FSH release

No effect on LH

Question 11

What are the helicine arteries?

Answer 11

Supply the cavernous spaces in the penis

In a flaccid state, these vessels are constricted

Question 12

What does the rigidity of an erection depend on?

Answer 12

Increae in flow of arterial blood into the cavernous

Decreased venous efflux resulting from compression of the subtunical venous plexus

Question 13

What is the role of efferent parasympathetic fibers in the erectile response?

Answer 13

Release NO and vasoactive intestinal peptide

These releax the helicine arteries and smooth muscle fibers

Question 14

What is emission and its control mechanism?

Answer 14

Movement of semen into the proximal part of the urethra

Controlled by sympathetic signals via NE

Question 15

What is the ejaculatory response?

Answer 15

Filling the urethra elicits sensory signals via pudendal nerve

Efferent signals trigger rhythmic contraction of the striated musculature of the perineum, especially the bulbocavernosus

Question 16

What are the clinical manifestations of testicular dysfunctions?

Answer 16

Infertility

Decreased Libido

Poor development of secondary sexual characteristics

Question 17

What is gynecomastia?

Answer 17

Benign enlargement of the male breast caused by the proliferation of glandular tissue

Results from exposure to excessive amounts of estrogen, decreased testosterone production

Question 18

What is primary hypogonadism?

Answer 18

Primary testicular failure

E.g. Klinefelter syndrome

Question 19

What is Klinefelter syndrome?

Answer 19

Most common type of hypogonadism in males

Most common karyotype is XXY

Question 20

What are the clinical symptoms of Klinefelter syndrome?

Answer 20

Seminiferous tubules are fibrotic and hylanized

germ cells are not present

Infertility

Leydig function is variable

Signs of androgen deficiency

Gynecomastia

Question 21

What are the lab findings in Klinefelter syndrome?

Answer 21

Elevated FSH and LH

Testosterone low to normal

Elevated Estradiol

Question 22

What is Orchitis?

Answer 22

Inflammation of the testes, usually secondary to mumps

Seminiferous tubule destruction

Leydig cells unaffected

Question 23

What is Kallmann syndrome?

Answer 23

Isolated gonadotropin deficiency caused by deficient production of GnRH

Second most common reproductive disorder in males

Often associated with defective sense of smell