CHAPTER 20 : Anatomy of the Male reproductive system.
primary sex organs : testes—> form the gametes —> round, enclosed in thick white membranous
outer coating —> tunica albaginea.
accessory organs: ducts and accessory glands, leading from testes to penis (organ of copulation,
external genitalia)
Functions of the testes : produce sperm + produce hormones.
Tunica albuginea projects internal to from septa: divide cavity in number of portions (250 lobules).
In lobules, 4 tubes called seminiferous tubules. (whose cells produce sperms). :
- sustentacular cells : help maintain nature of the sperm. form tight junctions between cells and
creates blood-testis barrier because immune cells in blood would try to destroy sperm being
produced since they are different from the male’s somatic cells.
- population of dividing germ cells that continuously produce sperm beginning at puberty.
Scrotum allows testes to be outside the body cavity to help maintain the environment at a lower
temperature (because rising temperature favours mutations).
Skin = with smooth muscle fibres (dartos muscle) which has capacity to change the structure of
the skin by contracting or relaxing. contract = wrinkling= warmer temperature.
Cremaster muscle = skeletal muscle attaches testis to the body. Contracts in cold temperature to
bring it closer to the body in order to warm up.
testis supported on a
rope of different
structures:
-internal cremaster
(regulate temperature)
-vas deferens (allow
sperm to go from testis
out of scrotum back to
base of penis)
-testicular nerves
-testicular arteries
-testicular veins (spread
out forming a network of
vessels: pampiniform
plexus)
-layers of peritoneum
(out from inguinal canal
(pocket un abdominal
muscles))
==> spermatic cords.
heat in arterial blood gets taken out by flow of cool blood from the veins
tubes enable mvmt of sperm from testis to where
it needs to get to
—> seminiferous tubules drain into network in
testes : rete testis
—> drain out via efferent ductules. move sperm
out testis.
—> drain into epididimis (single tube, with head
body and tail, long and coiled upon itself) where
it is stored + maturation
-{ trigger for ejaculation}—> into ductus deferens, that carry sperm back
up the spermatic cord, through pelvic
cavity(through inguinal canal), to base of penis.
—> moves through accessory glands .
ejaculatory duct
—> urethra (starts at base of bladder,
surrounded by prostate gland) transports semen
from ejaculatory ducts, and sperm, and urine.
Accessory glands: (secrete fluid to mix with sperm to create seminal fluid).
seminal vesicles: secrete viscous, whitish-yellow alkaline fluid containing fructose + prostaglandins
prostate gland : Encloses eurethra at its base. Secrete slightly acid fluid containing mucin citric
acid (nutrient for sperm) + antibacterial agents.
bulbourethral glands: secrete mucus into spongy urethra at the base of the penis. before
ejactulation to clean out eurethra.
semen:
Very viscous, needs to provide nutrients(number of different chemicals) to the sperm, + produce
protection for the sperm. Alkali chemicals neutralise acidic environment of vagina. When released,
its called an ejaculate.
Penis (encloses non-pelvic urethra)
- excretion (passage of urine) and ejaculation (reproductive passage of semen)
- changes it’s morphology depending on blood supply, volume, and pressure.
prepuce = double layer of skin protecting penis when not being used
Root of penis: attached portion of penis internally
shaft of penis = comprised of 3 parallel cylindrical erectile bodies : corpora cavernosa
(dorsolaterally, responsible for change of structure during erection), corpus spongiosum (make
sure that eurethra stays open), glans (distal end of c.s.)
erection : when venous spaces fill with blood from central artery. parasympathetic innervation
responsible for it.
emission: mvmt through male rep system
ejaculation : mvmt out of male rep system (by contraction of muscle tissue). sympathetic
innervation promotes it.
period of latency : rest between