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40 Cards in this Set
- Front
- Back
where are sertoli cells found and what is their function
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found within the basal lamin of the seminiferous tubule
support maturation of spermatogonia growth factors androgen binding protein beta-estradiol have FSH receptors |
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where are leydig cells and describe overall function
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found in the interstitium between seminiferous tubule
synthesize testosterone have LH receptors |
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what is the action of LH and which cell type does it affect?
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affects leydig cells
stimulates testosterone synthesis |
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what is the molecule necessary for testosterone production at the first step and how can it be obtained
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cholesterol
synthesized de novo or... LH stimulates the synthesis of sterol carrier protein for the transport of cholesterol into the cell |
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what enzyme is necessary for the conversion of cholesterol to the next molecule (what is it)?
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CYP11A1
pregnenolone |
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testosterone can be converted to what molecule and which enzyme is necessary for its production?
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DHT
5 alpha-reductase |
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what is the molecule that is immediately before testosterone is made?
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androstenedione
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what part of the cell is CYP11A1 found in?
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mitochondria
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what can testosterone be bound to when its not active?
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sex-hormone binding protein(SHBP_
albumin corticosteroid-binding protein |
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which molecule is more potent...testosterone or dihydrotestosterone (DHT)
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DHT
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testosterone is necessary for the differentiation of which male tissues?
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epididymis, vas deferens, seminal vesicles
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name some affects of testosterone on a growing male?
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increased muscle mass
pubertal growth spurt closure of epiphyseal plates growth of penis deepening of voice spermatogenesis libido |
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which is more important in negative feedback to the anterior pituitary---testosterone or DHT?
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testosterone
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DHT is necessary for the differentiation of which male tissues?
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penis, scrotum and prostate
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name the physical characteristics that DHT causes in a man
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male hair pattern
male pattern baldness sebacous gland activity growth of prostate |
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describe the interactions between sertoli and leydig cells
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leydig cells
take up cholesterol and synthesize testosterone testosterone diffuse across the BM and into the capillary network some testosterone crosses the BM of the sertoli cells testosterone is converted to estradiol through the action of aromatase- diffuses into circulation and some diffuses back into the leydig cells and governs their proliferation testosterone in the sertoli cell also stimulates production of ABP - testosterone binds to ABP and taken into the lumen of the seminiferous tubule |
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which cell type produces anti-mullerian hormone?
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sertoli cells
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describe the LH second messenger pathway in leydig cells
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LH has a receptor to which it binds on the leydig cell- GPCR
binding stimulates G protein and causes activation of adenyly cyclase adenylyl cyclase acts leads to the production of cAMP - cAMP actiavtes PKA PKA causes phosphyralation proteins that act as transcription factors these factors cross the nuclear membrane and control produciton of certain proteins - such as CYP11A1 - part of rate limiting step of testosterone production |
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describe the FSH second messenger pathway in the sertoli cells
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FSH binds to receptor
leads to activation of G protein which leads to activaiton of adenylyl cyclase increases cAMP this causes the activation of PKA PKA leads to production of transcription factors these transcription factors govern the production of proteins such as ABP, aromatase, inhibins and growth factors |
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discuss the actions that cause to the release of FSH and LH
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hypothalamus secretes GnRH
GnRH works at the level of the anterior pituitary and cases secretion of LH and SH LH works on leydig cells FSH works on sertoli cells leydig cells produce testosterone sertoli cells produce inhibins |
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describe the negative feedback associated with male gonadal function
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the inhibins produced by sertoli cells inhibits the action of the anterior pituitary
the testosterone produced by leydig cells can inhibit hte action of the hypothalamus testosterone can be converted to estradiol by aromatase and the estradiol can negatively affect the hypothalamus and anterior pituiatry |
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describe how the male genitalia form embryologically instead of female
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sertoli cells secrete anti-mullerian hormone
which causes regression of mullerian tubes - no uterus leydig cells secrete testosterone which causes the continued growth of the wollfian duct the wollfian duct differentiates into vas deferens, epididymus and seminal vesicles testosterone is converted to DHT by 5alpha-reductase causes the development of penis, penile urethra and scrotum |
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decribe how the testosterone levels change as puberty is entered
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prior to puberty testosterone levels are low(except during fetal and neonatal stages where theyare high as well)
onset of puberty -progressive and more frequent and greater amplitude of GnRH release -up-regulation of GnRH receptors on pituitary gonadotrophs -increased sensitivity of GnRH receptors |
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follow the path of the sperm
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detach from lumen of seminiferous tubules
rete testis efferent ductules epidiymus: appx 50 days ampulla of vas deferens ejaculatory duct prostatic urethra penile urethra |
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what is the acrosome?
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covering over the head of the sperm
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what are the three parts of the sperm
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head
midpiece tail |
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how would you classify the rate of spermatogenesis?
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constant
not accelerated by androgens or gonadotropins |
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what is the daily sperm production for a 20 yearl old male vs a 50-90 year old male?
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20: 6.5 million sperm
50-90 3.8 million sperm |
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how long does it take to transform a spermatogonia into a functional sperm?
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74 days
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name the four parts of the male sex act
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excitement
erection emission ejaculation |
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what leads to excitement?
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tactile stimulation
- glans penis -areas adjacent to male sex organs psychologic stimuli |
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sensory afferent are carried by what nerve
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pudental nerve
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what is the role of parasympathetics during the erection phase?
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acetylcholine release from parasympathetic fibers
casues release of NO NO acts on vascular smooth muscle and causes dilation of penile arterioles parasympathetic supply to the bulbourethral glands and urethral glands - leads to mucus production important in lubrication |
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what is the emission phase of the male sex act
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movement of sperm into prostic and/or proximal urethra
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during the emission phase fluid is provided from what areas of the male anatomy
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fluid from seminal vesicles
fluid from prostate fluid from cowper's glands |
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describe the parasympathetic action during the emission phase
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helps determ amount and consistency of sperm
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describe the sympathetic action during the emission phase
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contractions of ampulla of the vas, seminal vesicles, and prostate
constricts the internal sphincter of the bladder |
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what occurs during ejaculation
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forced expulsion of semen from the urethra
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how is the ejaculatory reflex triggered?
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movement of semen from the prostatic urethra into the bulbous urethra
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contraciton of what areas of the male anatomy are necessary for ejaculation
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perineal striated muscles
muscles surrounding corpus cavernosum and spongiosum |