Male Reproductive Tract Flashcards
What are the testis?
oval, paired gonad outside the body
How are the testis held to the body?
suspended by spermatic cord (vas deferens)
What are the membranes of the testis?
tunica albuginea, tunica vaginalis
When do the testes move into the scrotum? Why?
before puberty
because they need to be at a cooler temp for sperm production
What is cryptochidism?
failure of the testicles to descend
What do the muscles and scrotal skin do?
respond to changes in temp, shifting the testis to regulate heat
wrinkling, sweating
How does the scrotum keep cool?
meshwork of vessels on surface of skin
pampiniform plexus
How does the pampiniform plexus work?
venules carrying blood from testis cools arterial blood entering the testis to help regulate temp
veins of pampiniform plexus wrap around testicualr artery to increase surface area and maximize heat transfer
What are interstitial testis tissues?
tissues in between the testis
small arteries, capillaries, veins, leydig cells
What to leydig cells do?
sex determination during embryogenesis
onset and completion of puberty
maintenance and function of testis (spermatogenesis)
What temperature is the testis kept at?
33 C
What happens in the semineferous tubule?
sertoli epithelial cells with differentiating germ cells lying between them
germ cells go through meiotic and meiotic divisions while differentiating. move towards the lumen until they are released as mature sperm
What is the basal compartment?
section of the seminiferous tubule
bottom, where immature sperm are
What is the adluminal compartment?
inner 2/3 of tubule
spermatocytes and spermatids
What separates the basal and adluminal compartments?
blood-testis barrier, tight junction
What is the point of the blood-testis barrier?
protecting sperm from antibodies
What are myoid cells? What do they do?
contraticle cells surrounding seminiferous tubule, semi-permeable layer
regulates permeability of substances and secretions
What is spermatocytogenesis?
process of the progression of gonia through spermatocyte and spermatid stages
What is spermiogenesis?
structural and morphological changes that result in the transformation of the spermatids into mature sperm
What is the point of spermatogenesis?
generate reserve pool of germ line
What are the types of sperm (process)
Type A - Type Intermediate - Type B
Why does type A spermtogonia not go through complete cytokinesis?
they have cytoplasmic bridges that remain to connect them (pearls)
What defines a primary spermatocyte?
undergo first meiotic division to produce 2 dipliod cells (meiosis has 2 divisions so they are 2n)
Why are primary spermatocytes long lived?
they are in meiosis 1 which takes a long time to complete (faster than meiosis 2)
How can you “stage” stermatocytes?
viewing morphological stages of divisions
you can tell how far along it is in development
What happens to secondary spermatocytes? What do they form?
undergo 2nd meiotic division to produce 4 haploid cells
results in round spermatids
What is the sperm head?
nucleus with condensed chromatin
What is the acrosome?
thin membraneous sac, hydrolytic enzymes
What is the tail neck?
plate that hooks into posterior of nucleus and extends through tail
mitochonrdria layer
What is the tail middle?
outer layer of spirally arranged mitochondria, energy for mobility
9+2 arrangement
What is the 9+2 arrangement?
structure of the microtubules in the sperm tail
What are the stages of spermiogenesis? (4)
golgi, cap, acrosomal, maturation
What happens during the golgi phase of spermiogenesis?
formation of acrosomal granule from golgi membrane
adhesion of nucleus to membrane
start of tail development
What happens during the cap phase of spermiogenesis? (3)
spreading of acrosomal membrane over nucleus
slight tail elongation
can start to see 9+2 arrangement
What happens during the acrosomal phase of spermiogenesis? (4)
molding of acrosome, orients toward tubule wall
cytoplasm pushed towards tail
association of microtubles with axoneme (flagella)
sertolic cells begin to shape spermatid
What happens during the maturation phase of spermiogenesis? (3)
further condensation of nucleus
refinement of acrosome and tail
sertoli cell helps in formation and removal of residual body
How does FSH control spermatogenesis? (general 3)
ncreased conversion of T to DHT/estradiol
increased androgen binding protein (ABP) production in sertoli
secretion of inhibin in sertoli
maintenance of spermatocytogenesis
How do Sertoli cells (and ABP in them) respond to FSH in spermatogenesis? (3)
ABP is secreted into lumen and binds T and DHT
helps sequester androgens to maintain high concentrations near developing sperm
ABP and androgens travel into epididymis to keep T around to maintain sperm health
How do Sertoli cells (and inhibins and activins in them) respond to FSH in spermatogenesis?
inhibin inhibits FSH secretion from gonadotropins, activin activates secretion
How does LH control spermatogenesis (general 2)?
higher frequency of GnRH pulses may favor LH secretion
LH receptors on Leydig cells stimulate synthesis and testosterone secretion
How does desensitization and self regulation work in Leydig cells?
desensitization due to initial LH secretion and then a drop
prevents overstimulation
How do Leydig cells respond to LH in spermatogenesis? (4 steps)
testosterone synthesized and secreted
T mediates negative feedback response to HP
T can indirectly regulate CNS neurons to regulate repro function
sertoli and germ cells conversions into DHT/estradiol
What is testotoxicosis?
mutation of Gs protein to early onset puberty
don’t need LH to activate pathway (elevated T, secondary sex characteristics)
What is orchitis?
testis inflammation
What is priaprism?
persistant painful erection
Why is seminal fluid (semen) important? (why isn’t it just sperm?)
nutrition and fertilization
protection in vagina
What happens in spermiation? (3)
release of sperm from sertoli epithelium when mature
LH acts on sertoli to stimulate release of sperm heads
sperm swept away by secretion of sertoli (androgen binding protein bound to T)
What happens in the epididymis?
secretion of proteins to regulate metabolism and maturation of tail, sperm enter epididymis inmotile and exit mobile
immobilon
sperm forward-mobility protein
What does immobilion do?
prolongs sperm survival by keeping sperm immobile to give them time to develop (can’t move into vas deferens until ready)
What does sperm-forward-mobility protein do?
flexibility and movement of flagella
How do sperm move from epidydimis to vas deferens?
beating cilia and smooth muscle contractions
What happens in the vas deferens?
seminal fluid is formed, important to protect sperm and maintain ability to fertilize
What happens in the seminal vesicles?
paired glands at widening of vas deferens (ampulla) secrete alkaline (basic) fluids with fructose
What is the prostate gland? What happens in the prostate gland?
donut-shaped gland that surrounds urethra
alkaline secretions
What happens in the bulbourethral (Cowper’s) gland?
paired glands that secrete mucus to lubricate urethra
What does the muscular sphinctor between the bladder and urethra do?
contracts to prevent urine from entering urethra and from semen entering the bladder
What happens during an erection? (5)
vasocongestion (engorgement)
stimuli from genetalia transmitted to spinal cords via sensory neurons, erection reflex activates erection center
efferent neurons supply blood cells in penis (corpus cavernosum)
relaxation of the smooth muscle vessels causing vasodilation
increased cGMP
What happens during ejaculation? (4)
stimuli travels to ejaculation center in spinal cord
efferents activation contractions of muscles in testes, accessory ducts, glands
closure of bladder sphincter
penis muscle contractions
semen expulsion
