Male Anatomy and Physiology

Question 1

Male Sex Organs

Answer 1

serve a reproductive function; bring pleasure to self; give pleasure to others; may serve to attract potential sexual partners; sharing of genital sexuality can play a bonding role in relationships

Question 2

External structures

Answer 2

The penis and the scrotum

Question 3

Penis

Answer 3

from latin word for tail; organ through which sperm and urine pass;

Question 4

Three sections of penis

Answer 4

Root, shaft, corpora cavernosa, corpus spongiosum

Question 5

Root

Answer 5

attaches penis with pelvic cavity

Question 6

Shaft

Answer 6

contains 3 parallel columns of erectile tissue (corpora cavernosa (2) columns and corpus spongiosum (1) column)

Question 7

Corpora cavernosa

Answer 7

2 columns along the front surface of shaft

Question 8

corpus spongiosum

Answer 8

runs beneath the corpora cavernosa, also forms the glans (urethra)

Question 9

Glans Penis*

Answer 9

enlarged head of the penis; * most sexually sensitive

Question 10

Corona

Answer 10

rim at the base of the glans

Question 11

Frenulum

Answer 11

triangular area of skin that attaches the glans to the forskin

Question 12

Foreskin or Prepuce

Answer 12

sleeve-like covering glans

Question 13

circumcision

Answer 13

surgical removal of the foreskin

Question 14

urethra

Answer 14

a tube that transports urine and semen and runs from the bladder

Question 15

Scrotum*

Answer 15

• pouch of loose skin that holds the two testicles; skin is more heavily pigmented; sparsely covered with hair; divided in the middle by ridge of skin; * testicle temp control= 93 degrees F; two sets of muscles within the scrotal sac– Dartos muscle and cremaster muscle

Question 16

Dartos muscle

Answer 16

a smooth muscle under the skin that contracts and causes the surface to wrinkle

Question 17

Cremaster Muscle

Answer 17

fibrous muscle that causes the testicles to elevate

Question 18

Testes (internal structure)

Answer 18

two major functions: sperm and hormone production; shaped like olives, 1.5” long and 1” in diameter; size and weight decrease as men age; spermatic cord; within each testicle, there are about 1000 seminiferous tubules

Question 19

spermatic chord

Answer 19

located within the scrotal sac; suspends each testicle and contains a vas deferens

Question 20

seminiferous tubules *

Answer 20

• production of sperm takes place in these tubes; contain sertoli cells; between these are Leydig cells

Question 21

sertoli cells *

Answer 21

• manufacture inhibin which signals the hypothalamus to stop the production of GnRH, which in turn, signals the pituitary gland to stop the production of FSH

Question 22

Leydig cells*

Answer 22

also known as interstitial cells; between the seminiferous tubules; * responsible for producing testosterone

Question 23

Epididymis* (internal structure)

Answer 23

a tightly coiled tube that is connected to ducts inside the testicle; the head emerges from the top of the testis, descends along the outer surface, and then moves upward to become the vas deferens at its tail; * sperm are stored and mature here

Question 24

Vas Deferens (internal structure)

Answer 24

the tubes that transport sperm from the epididymis to the ejaculatory ducts

Question 25

Ejaculatory Ducts (internal structure)

Answer 25

formed by the union of the vas deferens with the duct of the seminal vesicle; they pass through the prostate; they open into the urethra

Question 26

Seminal Vesicles* (internal structure)

Answer 26

• small glands that lie behind the bladder; responsible for sperm cells; * produces a yellowish viscous fluid rich in fructose; this fluid makes up about 60% of the seminal fluid

Question 27

Prostate Gland (internal structure)

Answer 27

lies beneath the bladder; the fluid is milky and alkaline; this fluid makes up about 30-35% of the seminal fluid

Question 28

Cowper’s glands or Bulbourethral glands (internal structure)

Answer 28

positioned below the prostate; secretes a clear alkaline mucous that contributes to the cohesive-jelly like texture of semen; also known as pre-ejaculatory fluid or pre-cum

Question 29

Urethra (internal structure)

Answer 29

transports urine and semen from the bladder and ejaculatory ducts to the exterior of the body; about 8” in length

Question 30

Semen

Answer 30

has to provide a nutritive and protective medium for the sperm during their journey through the female reproductive tract, increases the motility of sperm out the male’s urethra and then once it is inside the vagina, helps neutralize some of the acidity in the male’s urethra and in the vagina, prevents the sperm from diffusing out of the semen

Question 31

Seminal Fluid

Answer 31

semen without the sperm; whitish viscous fluid; produced by contributions from the seminal vesicles, prostate gland, and Cowper’s gland

Question 32

Sperm

Answer 32

sperm production is called sperm atogenesis; an ongoing process from puberty onward; the avg male will produce roughly 525 billion sperm cells over a lifetime; a teaspoon of ejaculated semen contains 250 million sperm; healthy men produce sperm at a rate of about 60,000 every minute; each individual sperm takes about three months to grow; male is considerred clinically infertile if his sperm concentration falls below 20 million sperm per ml of semen; sperm occupy about 2-5% of the total ejaculate; the normal sperm pH ranges from 7.2-7.8; a sperm’s swimming ability (motility) and shape (morphology) are key factors to examine in a good semen analysis; the shape of sperm is an indirect measure of the quality of genetic information they contain; the number, motility and shape of sperm all generally decline with age

Question 33

Fertilization

Answer 33

Sperm cells contain receptors on the surface of the sperm head (similar to odor receptors in the nose); researchers believe that sperm can detect the “odor” of the released egg and follow its scent to locate it; the egg is usually covered by a thick layer of cells called the corona radiata; modern in-vitro fertilization techniques can by-pass this selection process and achieve fertilization with much fewer sperm; successful fertilization is now even accomplished with sperm that can’t swim; the sperm must then penetrate the zona pellucida, which is the outer layer of the egg

Question 34

corona radiata

Answer 34

serves as a blockade to restrict sperm from getting into the egg

Question 35

cryptorchidism

Answer 35

a medical term referring to the absence from the scrotum of one or both testicles; represents failure of the testis to move, or “descend”, during fetal development from an abdominal position into the scrotum; about 3% of full-term and 30% of pre-mature infant boys are born with at least one undescended testes; the most common birth defect of the male genitalia; most testes descend by the first year of life (the majority within three months) making the true incidence of cryptorchidism around 1% overall

Question 36

Testosterone

Answer 36

acts on seminiferous tubules to produce sperm; regulates sex drive; is responsible for development of secondary sex characteristics in puberty; influences growth of bones and muscle mass

Question 37

Hormones That Affect Male Reproductive Processes (1) *

Answer 37

*GnRH –> FSH –> stimulates seminiferous tubules –> sperm

Question 38

Hormones That Affect Male Reproductive Processes (2) *

Answer 38

GnRH –> * ICSH (interstitial cell stimulating hormone) –> stimulates Leydig cells –> testosterone