chapter 27: male reproductive system

sole purpose of the male reproductive system

produce sperm & introduce it to the female body

Sex determination results from interaction between ___ and ____ of mother and fetus

genes and hormones

when do gonads develop in pregnancy? (fetus is sexually undifferentiated before this)

5 to 6 weeks

if the fetus is male, what gonadal ridges will form?

glans of penis, urethra, & scrotum

if the fetus is female, what gonadal ridges will form?

glans of clitoris, labia minora, & labia majora

when is genitalia distinctly formed in pregnancy?

12 weeks

what is the penis homologous to?

vagina

what is the scrotum homologus to?

labia majora

gonads initially develop high in the ____ ___ and then migrate into the pelvic cavity (ovaries) or scrotum (testes)

abdominal cavity

embryonic connective tissue cord extending from gonad to pelvic cavity floo

gubernaculum

what is the vaginal process in males

the fold of the peritoneum that extends into the scrotum

Gubernaculum and vaginal process create ____ ___, a pathway of low resistance through groin & the most common site of hernias in males

inguinal canal

About 3% of boys are born with undescended testes, what is this called?

cryptorchidism

what does the gubernaculum become in females?

a pair of ligaments that supports the ovaries & uterus

primary sex organs (gonads)

testes & ovaries

secondary sex organs (organs other than gonads that are necessary for reproduction

male: system of ducts & penis deliver sperm

female: uterine tubes, uterus, and vagina receive sperm & harbor fetus

located in the perineum. most are externally visible, except accessory glands of female perineum which are subcutaneous

external genitalia

located in the pelvic cavity, except testes and some associated ducts in the scrotum

internal genitalia

pouch of skin, muscle, and fibrous connective tissue containing the testes

scrotum

which testicle usually descends lower

left testicle

divides scrotum into right and left compartments (prevent spread of infection)

internal median septum

a bundle of fibrous connective tissue containing the ductus deferens, blood and lymphatic vessels, and testicular nerve. located posteriorly in the scrotum

spermatic cord

what body temperature is needed to produce sperm?

35 degrees C

what mechanisms are in place to regulate the temperature of the testes

the cremaster, dartos fascia, and the pampiniform plexus

how does the cremaster regulate the temperature of the testes?

when it is cold, cremaster contracts to hold testes closer to body; when warm, cremaster relaxes and testes further from body

how does dartos fascia regulate the temperature of the testes?

smooth muscle contracts when cold, wrinkling the scrotum and holding testes against warm body; this reduces surface area of the scrotum and heat loss

how does the pampiniform plexus regulate the temperature of the testes?

this venous plexus surrounds testicular artery; countercurrent blood flow removes heat from descending arterial blood, to be carried away by ascending venous blood

the testes are considered both ____ & ____ glands bc they produce sex hormones and sperm

endocrine & exocrine

what is the white, fibrous capsule that cover the testes

tunica albuginea

the septa in the tunica albuginea divide the testis into how many lobules? with how many seminiferous tubules (where sperm is produced)?

250 to 300 lobes with 1 to 3 seminiferous tubules

located between the seminiferous tubules. produce testosterone

interstitial endocrine cells

seminiferous tubules are lined with thick germinal epithelium and are composed of

1. nurse cells—developing sperm

2. germ cells—supporting cells that protect/nurture nurse cells

3. blood-testis barriers (BTB)—tight junctions between nurse cells that prevent germ cells from being attacked

secrete fluid in the lumen of a seminiferous tubule high in androgens, estrogens, potassium, and amino acids. nutrients and chemicals that promote sperm development

nurse cells

binds androgens in seminiferous tubule – stimulates spermatogenesis (nurse cell produces)

Androgen-binding protein(ABP)

regulate sperm production by inhibiting follicle stimulating hormone (nurse cell produces)

inhibin

in developing testes. stops uterus and uterine tube formation (nurse cell produces)

Mullerian-inhibiting factor (MIF)

After leaving testis, sperm flow through series of spermatic ducts to reach urethra, what are they?

efferent ductules, epididymis, ductus deferens, and ejaculatory duct

about 12 small ciliated ducts collecting sperm from rete testes and transporting it to epididymis

efferent ductules

site of sperm maturation and storage. mature sperm travel through this duct and are reabsorbed if not ejaculated

epididymis

the tube between epididymis and seminal vesicle. its a thick wall of smooth muscle innervated by sympathetic nerve fibers

ductus deferens

2 cm duct formed where ductus deferens and duct of seminal vesicle merge. it passes through prostate and empties into urethra

ejaculatory duct

The 3 sets of accessory glands in male reproductive system:

seminal vesicles, prostate gland, and bulbourethral gland

empties into ejaculatory duct (60% of semen) and secretes proseminogelin (sticky to bind in female), citrate (nutrients for sperm), and prostaglandins (inhibit rejection of female immune system)

seminal vesicles

surrounds urethra and ejaculatory duct (30% of semen) & secretes bicarbonate/phosphate (buffer vaginal acid), citrate, clotting enzyme (activiates seminogelin, increases fertility), & serine protease (breaks down seminogelin)

prostate gland

Produce a clear slippery fluid (pre-ejaculate) that lubricates the head of the penis in preparation for intercourse (<1%). Protects sperm by neutralizing acidity of residual urine in urethra

bulbourethral gland

a noncancerous enlargement of the prostate. Compresses urethra and obstructs flow of urine making it harder to completely empty the bladder. May promote bladder and kidney infection

Benign prostatic hyperplasia (BPH)

why does prostate cancer typically go unnoticed?

only noticed when it becomes painful

what is used to diagnosed prostate cancer?

digital rectal exam (DRE), & elevated levels of serine protease (PSA), and acid phosphate in the blood

erectile tissue along ventral side of penis. encloses spongy (penile) urethra;

corpus spongiosum (1)

When the penis is flaccid, the trabeculae muscles of the 3 erectile tissues are ____ & they constrict arterial branches

contracted

this artery travels under skin of the penis on dorsal surface. supplies blood to skin, fascia, and corpus spongiosum. when penis is flaccid, most blood comes from this

dorsal artery

this artery travels through the core of the corpus cavernosa in the penis, gives off smaller helicine arteries that penetrate the trabeculae and enter cavernous spaces. any dilation of deep artery fills cavernous spaces causing an erection

deep artery

this vein drains blood from penis

deep dorsal

Characterized by vasocongestion (swelling of genitals with blood), myotonia (muscle tension), and increases in heart rate, blood pressure, and pulmonary ventilation

excitement phase of erection

when a male hits puberty, what does the hypothalamus start releasing?

gonadotropin hormone

male reproduction hormone

androgen

what does testosterone stimulate

sperm production, secondary sex characteristics, erythropoiesis, muscle mass, metabolism, and libido

process of producing spermatozoa

spermatogenesis

the first cell to arise that will eventually become an egg or a sperm

primordial germ cells

a spermatogonia daughter cell that remains in tubule wall as stem cell. it multiplies from puberty to death

type A spermatogonium

a spermatogonia daughter cell that migrates away from wall and is on its way to producing sperm enlarges, becomes a primary spermatocyte

type B spermatogonia

____ spermatocyte undergoes meiosis I, producing two haploid secondary spermatocytes

primary

Each ____ spermatocyte undergoes meiosis II, dividing into two haploid spermatids

secondary

in total how many spermatids are produced from each spermatogonium

4 spermatids

Each spermatid undergoes spermiogenesis, where it transformation into a ______ and forms a flagella, discarding the cytoplasm

spermiogenesis

mixture of glandular secretions coming mainly from seminal vesicles, prostate, and bulbourethral glands

seminal plasma

what is a normal sperm count

50 to 120 million

when is a male considered infertile?

sperm count less than 20 million