Male reproductive physiology

Question 2

Male Reproductive System Functions:

Answer 2

urine elimination and reproduction

Question 3

___ - spermatogenesis and secretion of testosterone (male sex
hormone)

Answer 3

Gonads (testes)

Question 4

_____ - transports and stores sperm, and assists in their maturation

Answer 4

Ductal system (epididymides, vas deferens, and ejaculatory ducts)

Question 5

_____ - produce the fluid constituents of semen

Answer 5

Accessory glands (seminal vesicles, prostate gland, and bulbourethral glands)

Question 6

____ - urine elimination and sexual function

Answer 6

Penis

Question 7

Testes lie within the scrotum which hangs
outside the abdominal cavity, Surrounded by two tunics:

Answer 7

○ Tunica vaginalis - outer layer derived from
the peritoneum
○ Tunica albuginea - deeper layer of dense
connective tissue

Question 8

The tunica albuginea divides the testes into
_____

Answer 8

200-300 wedge-shaped lobules

Question 9

Each lobule of the testes contains ____

Answer 9

1-4 tightly coiled seminiferous tubules where sperm is produced and a connective tissue stroma where Sertoli cells are located

Question 10

Testicular Functions

Answer 10

● Steroidogenesis (synthesis of
androgens or male sex hormones)
● Spermatogenesis (sperm
production)

Question 11

Spermatogenesis requirements

Answer 11

○ Sperm production requires
temperatures that are 2-3 degrees C
below body temperature
○ The position of the testes in the
scrotum and the unique blood flow
cooling mechanisms provide this
environment

Question 12

The testes produce several male sex hormones, what are they?

Answer 12

● Testosterone (steroid)
● Androstenedione and
dehydroepiandrosterone (DHEA)

Question 13

Dihydrotestosterone (DHT) active
metabolite _____

Answer 13

→ binds to same intracellular
receptors in target cells but more stable
than testosterone

Question 14

In the male embryo, testosterone is essential for ____

Answer 14

appropriate differentiation of the internal and external genitalia (DHT primarily), and is
necessary for descent of testes in the fetus

Question 15

Spermatogenesis begins ____

Answer 15

shortly before puberty and continues throughout the life of men.

Question 16

Sertoli cells

Answer 16

secrete inhibin and androgen-binding protein (ABP)
○ Located in the seminiferous tubules and activated by FSH
○ Surround the spermatogenic cells and provide structural support,
physical and nutritional support for germ cells (sperm)

Question 17

Spermatogenic cells (AKA spermatogonia)

Answer 17

These are the building blocks of spermatozoa

Question 18

The formation of a mature sperm from a primitive germ cell by
spermatogenesis takes approx. ____

Answer 18

74 days

Question 19

In the absence of testosterone or androgen receptors in the
Sertoli cells, spermatogenesis does not proceed beyond _____

Answer 19

the meiotic stage (exact mechanism unknown)

Question 20

Each milliliter of semen contains _____

Answer 20

about 100 million sperm.

Question 21

Reduction in sperm production is associated with _____

Answer 21

infertility

Question 22

After the seminiferous tubules, the
spermatozoa move into the _____

Answer 22

rete testis

Question 23

final site for sperm
maturation

Answer 23

the epididymis

Question 24

When ejaculation occurs, the smooth
muscle in the wall of the epididymis
contracts vigorously. This moves sperm into
the _____

Answer 24

vas deferens (ductus deferens).

Question 25

Accessory genital glands =

Answer 25

the paired seminal vesicles, bulbourethral glands (AKA Cowpers), and the prostate gland

Question 26

Seminal Vesicles

Answer 26

The seminal vesicles lie on the posterior wall of the bladder and consist of highly tortuous tubes that secrete fluid for the semen.

Question 27

Each of the seminal vesicles secretes:

Answer 27

● Fructose - provides energy for sperm motility ● Prostaglandins - cause reverse peristaltic contractions in the uterus and fallopian tubes to move sperm toward ovaries

Question 28

The seminal vesicles combine with the ampulla of the vas deferens to form the _____

Answer 28

ejaculatory duct which travels through the prostate

Question 29

Both the vaginal secretions and the fluid from the vas deferens are strongly _____

Answer 29

Acidic Sperm mobilization occurs at pH of 6-6.5 so the alkaline nature of the prostatic secretions is necessary for successful fertilization of the ovum

Question 30

Bulbourethral Glands

Answer 30

The bulbourethral glands are pea-sized glands located on either side of the urethra. The glands produce a clear, mucus-like secretion

Question 31

The hypothalamus secretes _____ which acts directly on the anterior pituitary gland

Answer 31

gonadotropin-releasing hormone (GnRH)

Question 32

FSH binds selectively to the Sertoli cells where it initiates ____

Answer 32

spermatogenesis

Question 33

_____ suppress LH secretion through direct action on the pituitary and hypothalamus

Answer 33

High levels of testosterone

Question 34

FSH is inhibited by a substance called ____ produced by the Sertoli cells

Answer 34

inhibin

Question 35

The three masses of tissue in the penis:

Answer 35

○ Corpora cavernosa (2)- fills with 90% of the blood during penile erection ○ Corpus spongiosum - prevents the urethra from pinching closed during erection. It remains pliable during erection while the corpora cavernosa becomes engorged with blood

Question 36

Neural Control of Male Sexual Function

Answer 36

Erection - controlled by the parasympathetic nervous system Ejaculation and penile relaxation - controlled by the sympathetic nervous system

Question 37

Erection process

Answer 37

● Initiated by dilation of the arterioles of the penis ● As the erectile tissue of the penis fills with blood, the veins are compressed which blocks outflow and adds to the turgor of the organ ● The integrating centers in the lumbar segments of the spinal cord are activated by impulses in afferent (sensory) nerves from the genitalia and descending tracts that mediate erection in response to stimuli ● The efferent (motor) parasympathetic fibers are in the pelvic splanchnic nerves. The fibers presumably release cotransmitters: acetylcholine and the vasodilator vasoactive intestinal polypeptide (VIP)

Question 38

Ejaculation: two parts

Answer 38

A two-part spinal reflex involving emission (movement of the semen into the urethra) and ejaculation proper (propulsion of the semen out of the urethra at the time of orgasm)

Question 39

Ejaculation: emission

Answer 39

Emission is a sympathetic response, integrated in the upper lumbar segments of the spinal cord and affected by contraction of the smooth muscle of the vas deferens and seminal vesicles in response to stimuli in the hypogastric nerves

Question 40

Ejaculation: ejaculation proper

Answer 40

Ejaculation - the semen is propelled out of the urethra by contraction of the bulbocavernosus muscle, a skeletal muscle. The spinal reflex centers for this part of the reflex are in the upper sacral and lowest lumbar segments of the spinal cord, and the motor pathways traverse the first to third sacral roots and the internal pudendal nerves