midterm physio deck 5 Flashcards
exocrine testes vs endocrine testes
exocrine = seminiferous tubules produce male gamete/spermendocrine = interstitium testis produce male sex hormone (testosterone)
scrotumtunica vaginalistunica albuginea
thin skin coveringtv = middleta = fibrous layer beneath tunica vaginalis
septula testismediastinum testis
st = CT divisionsmt = area where blood and lymphatics, ducts and nerves run into the center of the testis
what structure transports and produces semen
seminiferous tubules
leydig cells
in the interstitiumthe produce testosterone
sertoli cells
in the seminiferous tubules; tall columnar and attached to basal laminanonreplicating nurse cells for developing spermthey form the blood testis barrier
5 sertoli cell functions
blood testis barrier (spermatogenetic cells are foreign to the body)support and nutrition for spermatozoaphagocytosissecretion of androgen binding proteinsynthesis of inhibin (feedback on FSH in pituitary)
spermatogenesis
spermatogonia develop into spermin proliferation, mitosis divisions maintain cell population and meiosis division reduced DNA content in halfdifferentiation = change in morphologyspermatogonia –> primary spermatocytes –> secondary spermatocytes –> spermatids –> spermatozoa
spermatogonia
stem cells, next to basal laminamitotically divide to maintain population
primary spermatocytes
undergo first meiotic division, large cells, 4n ch/2d DNA
secondary spermatocytes
short lived, undergo second meiotic division without DNA synthesis –> 1n ch/1d DNA
spermatids
close to lumen, undergo spermigenesishaploid DNA1 spermatocyte makes 4 spermatidschange to spermatozoa does not involved cell division!
spermatozoa
look mature but not motile or functional yet!
spermatogonium enter meiosis with ______ chromosomes and ______ DNA
diploid (2n)tetrapoid (4n)
homologous dyads =
sister chromatids
chiasma/crossing over occurs during
prophase 1
in PMAT of meiosis, when do sister chromatids move back to poles
anaphase 1
at the end of telophase 1,
resuling daughter cells are haploid (1n)
in anaphase 2
single chromatids move towards poles
at the end of meiosis,
4 daughter cells w 1n dna and 1n chromosomes(in fertoilization, will fuse w egg to form 2n zygote)
three phases of spermatogenesis
golgi phase - proacrosomal vesicles fuse in the golgi and form acrosomal vesiclesacrosomal phase - vesicle expands, flagellum forms, and mitochaondria condensematuration phase - cytoplasm shed (residual bodies) and phagocytosed by sertoli cells and spermatozoa are released
the spermatozoa that leave the seminiferous tubules are…
immotile and immaturematuration takes place in the epididymishead is an acrosomal cap with enzymes in itDNA is in the nucleus in the headneck has mitochondriatail has contractile elements
epididymis
made of pseudostratified epitheliumthis is where spermatozoa maturewhen they leave, they are motile but not activated
where does activation of sperm occur
in the female genital tract
cells of the endocrine testis are the
leydig cells in the interstitium near blood vesselsthey secrete testosterone (appears as crystal of reinke)
temperature control for sperm viability
requires lower temperature than the core body tempdone by:-testis are outside of peritoneal cavity-suspended by cremaster muscles-cooled by venus pampiniform plexus
cryptorchidism
undescended testis
hydrocele
fluid accumulation in the tunica vaginalis
tubuli rectirete testis
Tubuli recti - straight tubules; terminal end of seminiferous tubules, connecting to rete testisrete testis - interconnected channels in mediastinum testis
efferent ductules
connect rete testis to ductus epididymis, move sperm, and absorb fluid
epididymis
pseudostratified epithelium with stereociliafilled with maturing sperm, where they get motility but not activated
ductus deferens
three layers of SM, epithelium w stereociliapropel sperm by providing strong peristaltic motions during ejaculation
seminal vesicles
paired, folded tubular gland that secretes fluid containing fructose and prostaglandins = the propellant for spermactive protein synthesis and secretions
prostate
tubuloalveolar glands that empty into the prostatic urethrasynthesizes and stores PSA, fibrolysin and citric acid that are part of semen
bulbourethral glands (cowpers)
pea sized paired tubuloalveolar glands that secrete pre-seminal mucus like fluid = a lubricant
erection mechanism
parasympathetic stimulationincreases AChVIP and nitric oxide increasesincreased cGMP and SM relaxes blood flows into corpora cavernosa and peripheral veins compress so blood cant flow out
sildenafil (viagra)
blocks PDE5 that breaks down cGMP so cGMP increase is sustained = longer erection
sympathetic stimulation does what to erection…
terminates it by causing contraction of trabecular SM cells of the helical arteries
semen composed of what?
fructose and PGs from seminal vesiclesacid phosphatase, fibrolysin, and citric acid from prostateand preseminal fluid lubricant from cowpers glands
default sexual differentiation is
female pathway
genetic sex is determined by…
penetration of the ovum by either an x or y spermatozoa
internal genitalia determines…external genitalia determines…
I - somatic sexE - phenotypc sex
indifferent gonad develops from the….accompanied by two structures…
genital ridgemesonephric duct (wolfian)paramesonephric duct (mullerian)
wolfian duct
gives rise to male internal sex structures
mullerian/paramesonephric duct
gives rise to female internal sex structures
urogenital sinus becomes
external genitalia
indifferent gonads differentiate in the male earlier than the female….
6 weeks for male and at 8-9 weeks for female
what triggers the cascade events for male differentiation?
testosterone and MIF (mullerian inhibitory factor)–MIF is secreted by the sertoli cells in response to SOX9
what triggers female sexual differentiation?
absence of MIF and estrogen**wolffian regresses
5 genes that help differentiate the testes
TDF (testis determining factor)H-Y antigenzinc-finger Y (ZFY) geneSRY (sex region on y chromosome)SOX9
what stimulates development of : epididymis, vas deferens, seminal vesicles, and ejaculatory duct?
testosterone; do NOT require conversion of T to DHT
external male genitalia like penis, muscles and hair follicles they require
testosterone to be made into DHT by 5 alpha reductase
5 alpha reductase
tranforms T to DHT
what stimulates the fetal testes to produce testosterone?
hCG human chorionic gonadotropin from the placentahcg acts like LHmaternal LH cant because it cant cross the placenta
5 alpha reductase deficiency causes
androgen insensitivity syndromeT isnt converted to DHT so external genitalia and 2ndary characteristics are affected in male –> testicular feminization
what produces MIF?
sertoli cells of the fetal testis
in absence of hormonal stimulus the paramesonephric duct spontaneously forms
oviduct, uterus, and upper vagina
until when is there potential for either external genitalia
until 6-7 weeks
genital tubercle becomes
penis or clitoris
urethral folds become
penile uretha (corpus spongiosum) or labia minora
genital swellings become
scrotum or labia majora
urogenital sinus becomes
prostate or lower 2/3 of vagina
what is the mechanism by which the condition of Congenital adrenal hyperplasia is associated with a masculinization of a female fetus?
excess androgens due to not enough negative feedbackbaby with inadequate cortisol and aldosteroneemergency
the last structure to undergo irreversible programming in sexual differentiation is
the hypothalamusintrinsically female and will have cyclic release of gonadotropins; masculinization is mediated by androgens
if the hypothalamus is under presence of androgens
it will be masculinized and become unresponsive to the cyclic positive feedback of estrogen
at puberty, changes occur in hypothalamus
set point for gonadotropin inhibition by sex steroids rises, gonadotropin secretion increases and a concomitant increase in sex steroids occurs
additional hypothalamic maturation step is
the establishment of a + feedback mechanism for estrogen on the release of LH and FSH – will evoke midcycle surge of gonadotropins necessary for ovulation
childhood obesity is setting the stage for
metabolic syndrome= obesity, HTN, hyperlipidemia and insulin resistanceit is a chronic proinflammatory state
