Male Reproduction

Question 1

present at birth (internal and external genitalia)

Answer 1

primary sex characteristics

Question 2

emerge during puberty

Answer 2

secondary sex characteristics

Question 3

gene on the Y
chromosome directs
male development

Answer 3

SRY gene

Question 4

Two principal functions of the testes

Answer 4

sperm production

testosterone synthesis

Question 5

Testes are primarily
regulated by the

Answer 5

Hypothalamic-Pituitary-
Gonadal (HPG) axis

Question 6

secreted in a pulsatile
manner and causes the release of both LH and FSH

Answer 6

GnRH

Question 7

favored with fast pulses of GnRH

Answer 7

LH

Question 8

favored with slow pulses of GnRH

Answer 8

FSH

Question 9

GnRH output altered by environmental and social factors

Answer 9

day length, stress, negative feedback from steroids, nutrition, ambient temperature, and the presence of a reproductive partner

Question 10

a major regulator of GnRH neurons

Answer 10

KISS neuron

Question 11

relay signals from
the periphery to GnRH neurons to regulate

Answer 11

KISS neurons and GnIH

Question 12

receive signals about energy balance and convey this to GnRH neurons to regulate HPG axis activity

Answer 12

KISS neurons in the arcuate nucleus

Question 13

KISS neurons have receptors for:

Answer 13

Leptin - high leptin/energy = positive signal from KISS neurons
ghrelin- low energy/low ghrelin = no signal from KISS neurons

Question 14

Sex steroids regulate
GnRH indirectly through

Answer 14

KISS neurons

Question 15

Puberty begins when

Answer 15

GnRH secretion is triggered by KISS

Question 16

Maturation of Sertoli and Leydig Cells

Answer 16

puberty

Question 17

stimulates spermatogenesis
(sperm production) in
Sertoli cells

Answer 17

FSH

Question 18

stimulates
steroidogenesis in
Leydig cells

Answer 18

LH

Question 19

Testosterone is produced by the interstitial blank cells, which lie in clusters between the seminiferous tubules

Answer 19

leydig cells

Question 20

the principal role is the synthesis and secretion of testosterone

Answer 20

leydig cells

Question 21

Comprised of supporting cells (Sertoli cells) and developing sperm cells

Answer 21

Seminiferous Tubules

Question 22

Sperm are formed and develop within

Answer 22

Seminiferous Tubules

Question 23

are needed for maximal sperm production

Answer 23

testosterone from Leydig cells

FSH

Question 24

sperm cell development through mitotic and meiotic divisions and finally a metamorphic change to produce spermatozoa

Answer 24

Spermatogenesis

Question 25

takes ~72 days but sperm are produced continuously (>200 million/day)

Answer 25

Spermatogenesis

Question 26

support and nourish the immature sperm cell in Seminiferous Tubules by giving them nutrients and blood products

Answer 26

sertoli cells

Question 27

seminiferous tubule cell developing into sperm

Answer 27

Spermatocytes

Question 28

seminiferous tubule cells that are stem cells

Answer 28

Spermatogonium

Question 29

stimulates Sertoli cell functions are the only cells with FSH receptors in human males

Answer 29

FSH

Question 30

Secretes androgen-binding protein (ABP) = carrier protein that concentrates testosterone in testes

Answer 30

sertoli cells

Question 31

Produce nutrients for sperm

Answer 31

sertoli cells

Question 32

Forms the blood-testis barrier

Answer 32

sertoli cells

Question 33

Secretes inhibin

Answer 33

sertoli cells

Question 34

physical barrier between seminiferous tubules and blood vessels; formed by tight junctions between Sertoli cells

Answer 34

Blood-testis barrier

Question 35

isolate differentiating sperm cells from the bloodstream

Answer 35

Blood-testis barrier

Question 36

Protein hormone secreted from Sertoli cells in response to FSH

Answer 36

inhibin

Question 37

Concentration in blood is reflective of the number of functioning Sertoli cells and spermatogenesis

Answer 37

inhibin

Question 38

the primary testicular factor regulating FSH Inhibits transcription of the gene encoding the β-subunit of FSH

Answer 38

Inhibin B

Question 39

The principal steroid hormone (aka androgen) produced from testes

Answer 39

testosterone

Question 40

Transported via carrier proteins: -SHBG (sex-hormone binding globulin) -Albumin Binds to intracellular androgen receptor

Answer 40

testosterone

Question 41

Maturation of Reproductive Organs and Secondary Sex Characteristics

Answer 41

puberty

Question 42

Effects of puberty

Answer 42

* Pubic/facial hair & oil glands emerge * Reproductive tissues enlarge * Increased muscle mass (upper torso) * Larynx enlarges & vocal cords thicken * Increased sexual behavior (libido)

Question 43

Absence of testicular enlargement by age 14 -Causes: genetic delay in HPG axis development, undernutrition, or illness Development can be delayed for several years and eventually occur normally (“constitutional delay”)

Answer 43

Delayed/Deficient Puberty

Question 44

Functional or persistent hypogonadism (low testosterone) requires hormone replacement therapy due to

Answer 44

Delayed/Deficient Puberty

Question 45

Early puberty (< age 9 in males) Causes: premature activation of HPG axis, increased sensitivity to LH/FSH, or a tumor disrupting negative feedback Premature/rapid early growth leads to shorter stature as adults Treatment – puberty blockers (suppress LH and FSH)

Answer 45

Precocious Puberty

Question 46

Functions of Testosterone & its Metabolites in Adults

Answer 46

* Maintains secondary sex traits * Sperm production * Stimulate and maintain bones * Stimulate sexual behaviors * Negative feedback (primarily estrogen)

Question 47

ow testosterone that can cause infertility

Answer 47

hypogonadism

Question 48

decreases secretion of GnRH

Answer 48

obesity

Question 49

Progressive decline in testosterone starting ~40 yrs. and sperm production drops ~30%

Answer 49

old age

Question 50

decline in testosterone production with age

Answer 50

Andropause

Question 51

Anabolic androgenic steroids (AAS) are a synthetic version of testosterone that enhance androgenic effects, like larger muscle mass, but you also get... * Breast enlargement * Reduced testicular size * Low sperm count (infertility)

Answer 51

sex steroids to increase testosterone

Question 52

Effects of anabolic androgenic steroids on fertility

Answer 52

most likely will make you infertile