male urogenital system Flashcards
male blood supply
testicular artery from aorta
venous drainage from IVC
spermatozoa
smallest human cell
3 micron diameter
highly condensed DNA
functions of testis
production of spermatazoa and male sex hormones
divisions of tubules
seminiferous tubules -> rete testes -> into epididymus
centre of seminiferous tubules
spermatozoa
production of cells occurs from maturation from the peripheral to central region of the tubule
interstitium between tubules contains
leydig cells = hormone production (androgen)
blood, nerve and lymph vessels
making sperm called
spermatogenesis
stages of sperm cells in 3 phases of life
fetal = primordial germ cells populate the testes with spermatogonia childhood = cells quiescent puberty = spermatogenesis begins
initial mitosis produces
spermatogonia (A) produces spermatogonia (B) and replenishes the stem cell pool
spermatogonia (B) undergo mitosis to produce primary spermatocytes
primary spermatocytes undergo
meiosis 1
secondary spermatocytes undergo
meiosis 2
stages of mitosis into mature cells
primary spermatocytes -> secondary spermatocytes (meiosis 1)
secondary spermatocytes -> round spermatids (meiosis 2)
round spermatids -> differentiating spermatids -> residual bodies and spermatozoa
cytoplasmic bridges between cells function
allows for synchronisation
can transfer mRNA and proteins between haploid cells
how does differentiation occur in the tubule
from the peripheral to the lumen
function of Sertoli cells
form the blood-testis barrier
support
why is the blood testis barrier needed
spermatogenesis begins after immune system is developed so sperm are ‘foreign’
Sertoli cells control lumen environment, separate lumenal and basal comportments. support spermatogenesis, secrete nutrients, absorb waste and phagocytose defunct sperm
unique feature of cell divisions
divisions are incomplete
cells remain linked together and have junctional contacts with sertoli cells
features of sperm DNA
DNA is packed more tightly than somatic cells
sperm DNA packed on protamines, not histones
length of spermatogenesis process
about 60 days
new cohorts begin about every 12 days
within the tubule, adjacent parts are at different stages
spermiogenesis stages
Golgi phase -> cap phase -> acrosome phase -> maturation
features of sperm maturation
- Golgi assembles on one side, will form acrosome
- opposite side to this is flagella development, mitochondria move closer to flagella
- much of cytoplasm lost
- on top of acrosome plasma membrane, get receptors for the zona pellucid and oocyte membrane
features of mature sperm
- mobile
- receptors for zona pellucida and oocyte
- can penetrate the zona pellucida and activate oocyte
endocrine control from puberty
hypothalamic kisspeptin neurons activated
GnRH released in pulses from hypothalamus
stimulates secretion of FSH and LH
feedback control of hormones to pituitary and hypothalamus
action of FSH
initially stimulates Sertoli cell division, then secretion (specific protein)
action of LH
acts on Leydig cells to produce testosterone and androgens
epididymus structure
very long could tube, about 7m
4-6 weeks for sperm to pass through
function of epididymus
sperm maturation
removes cytoplasmic droplet from spermatozoa
adds a glycoprotein coat over sperm heat
concentrates spermatozoa
allow development of unidirectional motility
function of vas deferens
transport spermatozoa and can store them in its ampulla
contract mainly in relation to sympathetic stimulation
seminal vesicles pass into vas deferens
seminal vesicles function
produce the major fluid component of sperm
produce fructose as energy
contracts mainly in relation to sympathetic NS
prostate function
androgen dependent
produce some factors in seminal fluid, not well understood
key organ in cancers
constituents of sperm
20 million sperm/ml
seminal vesicles (2/3 volume) = fructose, fibrinogen, prostaglandins
prostate (1/3 volume) = bicarbonate buffers, enzyme, citric acid, exosomes
a few drops from bulbourethral gland = buffers. mucus
what occurs during arousal
erection and arteriolar vasodilation
how does arousal occur
NO (parasym) and cGMP, veins compressed and blood pressure increases
- elevation of scrotum
- elevation and swelling of testes
what occurs during plateau
distension of penis and testis, mucus bulbourethral gland secretion
what occurs during orgasm
emission with contraction of tubules and relaxation of urethras sphincter (sympathetic), ejaculation with rhythmic contraction of perineal striated muscle and anal sphincter (somatic)
what occurs during refractory resolution
return to non-aroused state
phases of nervous control
parasympathetic
sympathetic
somatic
position of testes
in scrotum
function of the vasa efferent
connect the rete testes to the head of the epididymus
route of vas deferens
passes through the inguinal canal and exits the deep inguinal ring down to each testis
control of testis temperature
kept cool in counter current heat exchange
cremaster and dartos muscles
contract the scrotum and draw the testis into the abdominal cavity when cold
effects of testosterone
secondary sexual characteristics growth of reproductive organs hair growth increased libido voice drops
