male reproductive system

gonads

• testes

• produce gametes (sperm) and testosterone

secondary sex organs

• aid in the formation semen (seminal fluid) and the transport of semen

• epididymis, ductus deferens, ejaculatory duct, seminal vesicles, prostate, bulbourethral glands and penis

testes

• location

• a. outside pelvic cavity

• within scrotal sac (scrotum)

• function

  • a. production of sperm

  • b. production of testosterone

• structure

  • small, oval

  • surrounded by CT

seminiferous tubules

• inside testes

functional unit

a. site of sperm production (thousands/sec)

b. spermatogonia — sperm in various stages of development

c. sertoli cells — “nurse cells” line tubules and produce nutrients required to maintain developing sperm

leydig

• in testes

produce and secrete testosterone

responding to LH — luteinizing hormone → production of testosterone

mature sperm

• in testes

a. structure

1. head, body, tail

2. acrosome—located at tip of head, contains enzymes which help penetrate ovum

3. 23 chromosomes (22 autosomes, 1 sex chromosome (allosome)) X or Y

b. life expectancy

• 48-72 hours after ejaculation at body temperature

c. ejaculate

• approximately 50-150 million per milliliter

• only 200-400 reach the ovum

development of the testes

• testes develop in abdomen and descend into scrotal sac through the inguinal canal at the 28th week of gestation

• the inguinal canal is a passageway through lower abdominal wall that connecting the abdomen to the scrotal sac

• if the testes don’t descend by age 5 they are surgically placed in scrotal sac

inguinal canal

• passageway through the abdominal wall allowing for the passage of the testes and the spermatic cord into scrotal sac

inguinal hernia

refers to the defect in the abdominal wall which allows portions of intestine to pass through the inguinal canal and enter scrotal sac

spermatic cord

• “life-line”

• CT sheath containing:

  • vas deferens

  • testicular artery

  • pampiniform plexus of veins

  • nerve

  • lymphatics

epididymis and vas deferens

the tubules or ducts in the testes which transmit sperm

epididymis

location

• attached to the posterior surface of the testes

structure

• a. coiled tube (17 feet long)

• b. contains millions of sperm in their final stage of development

function

• stores sperm

• transports sperm from testes to the ductus deferens

ductus deferens

also called vas deferens

location

• a. passes from scrotal sac (outside pelvic cavity)

• b. travels within the spermatic cord to enter the pelvis

structure

• fibromuscular tube

function

• transports sperm from the epididymis to the ejaculatory duct

vasectomy

• cutting and ligating ductus (vas) deferens

• prevents sperm from passing through this tube and entering urethra

• ejaculation continues as before, but semen contains no sperm

ejaculatory duct

• formed by union of ductus deferens and the duct of seminal vesicles

• passes through prostate gland to join the prostatic urethra

accessory glands

produce seminal fluid

1. seminal vesicles

2. prostate gland

3. bulbourethral glands/cowper glands

seminal vesicles

location

• posterior to the bladder near its base

structure

• glandular organs

• contain smooth muscle which contracts to release fluid from the glands

function

• produce an alkaline secretion rich in fructose (sugar) used to provide energy for sperm (makes up 60% of seminal fluid)

• secrete prostaglandins that are capable of causing uterine contractions to help sperm move through this organ

prostate gland

location

• just inferior to the neck of the bladder

• surrounds the first portion of the urethra (prostatic urethra)

structure

• size and shape of a chestnut

function

• secretes an alkaline fluid which contains enzymes

• helps to neutralize acidic environment of vagina (30% of semen)

bulbourethral (cowper’s) glands

location

• muscular layer of the pelvic floor

structure

• small glands with a duct opening into the urethra

function

• secrete a mucous-like fluid which lubricates the urethra

scrotum

location

• somewhat posterior to the penis

structure

1. sac-like structure covered by fascia (CT) and skin

2. contains muscle fibers (cremaster muscle)

scrotum function

• supports and protects testes

• helps to regulate the position of the testes and thereby regulate their temperature

• optimum temp for sperm production is 95 F

• a. when cold:

  • cremaster muscle contracts and pulls testes up towards warm body wall

• b. when hot:

  • skin is more flaccid & loose

  • cremaster muscles relax allowing testes to be further away from body wall

penis

structure

1. shaft

   1. contains highly vascular tissue

   2. composed of sponge-like = erectile tissue

2. glans
   - expanded, terminal position
   - contains opening of urethra
   - foreskin - retractable portion of skin (removed during circumcision)

3. contains penile urethra - passageway for both sperm and urine

erection

• under parasympathetic control

• occurs when vascular spaces become engorged with blood and blood is not permitted to drain

• erectile tissue becomes rigid

ejaculation

• under sympathetic control

• affects smooth muscle of the glands and vessels of the reproductive system