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79 Cards in this Set
- Front
- Back
what does the testis consist of
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900 coiled seminiferous tubules where sperm are formed
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how long are the seminiferous tubules
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more than one half meter
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where do sperm go after the seminiferous tubules
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epidydimis (coiled tube about 6 m long), then ampulla of the vas deferens, then body of prostate gland
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where are the seminal vesicles
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one on each side of the prostate and empty into the prostatic end of the ampulla
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where do the contents of the seminal vesicles and ampulla go
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into ejaculatory duct through body of prostate and into the internal urethra
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what supplies the urethra with mucus
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minute urethral glands along entire extent and bilateral bulbourethral glands near origin
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immature germ cells
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spermatogonia
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where are the spermatogonia located
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2 or 3 layers of the inner surfaces of the seminiferous tubules
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where does spematogenesis occur and what causes it
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seminiferous tubules during active sexual life due to stimulation by anterior pituitary gonadotropic hormones
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first stage of spermatogenesis
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spermatogonia migrate amoung Sertoli cells toward the central lumen of the seminiferous tubule
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Sertoli cells
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very large, with overflowing cytoplasmic envelopes that surround the dvlp spermatogonia all the way to the central lumen of the tubule
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spermatogonia divisions are they cross the barrier into the Sertoli cell layer
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enlarged to form primary spermatocytes which divide into secondary spermatocytes which divide into spermatids which are modified to become spermatozoa
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length of process from spermatogonia to spermatozoa
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~74 days
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acromosome
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thick cap outside of the anterior 2/3 of the sperm head
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what forms the acromosome
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Golgi mostly - similar enzymes to lysosomal enzymes (hyaluronidase and proteolytic enzymes)
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3 componenta of the sperm tail/flagellum
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1) central skeleton of 11 microtubules (axoneme) 2) thin cell membrane covering axoneme 3) collection of mitochondria surrounding axoneme in proximal portion
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normal sperm speed
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1-4 mm/min
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what secretes testosterone
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Leydig cells in the interstitium of the testis
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LH fxn
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stimulates Leydig cells to secrete testosterone
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FSH fxn
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stimulates Sertoli cells
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what forms estrogens
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sertoli cells form from testosterone when stimualted by FSH
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GH fxn
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control background metabolic fxns; promotes early division of spermatogonia
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when do sperm gain motility
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after being in the epididymis for 18-24 hours
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how many sperm can be produced daily
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up to 120 million
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where are sperm stored
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some in epididymis, but most in vas deferens
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how long can sperm be stored
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at least a month and maintain fertility
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maturation
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after ejaculation, sperm become motile and become capable of fertilizing the ovum
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what environment enhances activity of sperm
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neutral and slightly alkaline medium; increased temperature (also shortens life)
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life expectancy of sperm in female reproductive tract
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1-2 days
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seminal vesicle secretes what
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fructose, citric acid, other nutrient substances, large quantities of prostaglandins and fibrinogin
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how do prostaglandins aid in fertilization
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1) react with female cervical mucus to make it more receptive to sperm movement 2) causing backward, peristaltic contractions in uterus and fallopian tubes to move sperm toward ovaries
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what does the prostate gland secrete
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thin, milky fluid containing calcium, citrate ion, phosphate ion, clotting enzyme, and profibrinolysin; slightly alkaline
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at what pH do sperm become optimally motile
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6.0 to 6.5 (female vaginal secretions are 3.5 to 4.0)
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breakdown of semen
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fluid and sperm from vas deferens (10%), seminal vesicles (60%), prostate (30%), small amounts from mucous glands (bulbourethral)
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what gives semen a mucoid consistency
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seminal vesicles and mucous glands
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what is the fxn of the clotting enzyme from prostatic fluid
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causes fibrinogen of seminal vesicle fluid to form a weak fibrin coagulum that holds semen in the deeper regions of the vagina
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capacitation of spermatozoa
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1) uterine and fallopian tubes wash away various inhibitory factors 2) lose excess cholesterol making acrosome weaker 3) membrane becomes permeable to Ca2+ incresing flagella action and release of acrosome enzymes
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what does hyaluronidase do in fertilization
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depolymerizes the hyaluronic acid polymers in intercellular cement that hold ovarian granulosa cells together
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what prevents multiple sperm fertilization
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Ca2+ ions diffuse inward once one sperm enters ovum - causes multiple cotical granules to be released
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cryptochidism
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failure of testis to descend from the abdomen into the scrotum at or near the time of birth
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at what sperm count is a male likely to be infertile
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less than 20 million per mL (normal 120 million per mL)
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most important source of sensory nerve signals for initiating the male sexual act
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glans penis through pudendal nerve
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how does cantharidin cause aphrodisiac symptoms
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irritate bladder and vascular congestion
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what reflex mechanisms cause the male sexual act
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integrated in the sacral and lumbar spinal cord
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what can initiate male sexual act
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psychic from brain or sexual stimulation of sex organs - usual combo of both
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what causes erection
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parasympathetic impulses from the sacral portion of spinal cord through pelvic nerves to penis
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what do the penile nerves release
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NO and/or vasoactive intestinal peptide in addition to acetylcholine
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where do smooth muscles relax to cause erection
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corpora cavernosa and corpus spongiosum in the shaft of the penis
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what are the 2 corpora cavernosa surrounded by
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strong fibrous coats - causes penis to become hard and elongated
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what occurs without enough lubrication during sex act
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male act is seldom sucessful due to grating, painful sensations that inhibit sexual sensations
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where do the sympathetic impulses come from during emission and ejaculation
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T12 to L2 through hypogastric and pelvic sympathetic nerve plexuses
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what does emission begin with
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contraction of vas deferens and ampulla, then contraction of muscular coat of prostate and seminal vesicles
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what does filling of the urethra with semen elicit
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sensory signals sent through pudendal nerve to sacral region of cord give feeling of fullness in internal genital organs
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What do sensory signals cause
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contraction of ischiocavernosus and bulbocavernosus muscles that compress the bases of the penile erectile tissue
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androgens secreted by the leydig cells in the testes
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testosterone, dihydrotestosterone, and androstenedione
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most abundant vs most active androgen
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testosterone most abundant with dihydrotestosterone the most active in target tissues
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what mass do leydig cells constitute in the testes
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~20% in adult
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definition of androgen
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any steroid hormone that has masculinizing effects
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arrhenoblastoma
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excess androgen formation due to ovary tumor
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what can androgens be produced by in the adrenals and testes
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cholesterol or from acetyl coA in both
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what does testosterone bind in plasma
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97% loosely binds albumin or tightly binds beta globulin called sex-hormone-binding globulin
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how long does testosterone circulate in plasma
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30 minutes to several hours
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what occurs to testosterone that isn't fixed into tissues
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converted to androsterone and dehydroepiandrosterone by liver; conjugated as glucuronides or sulfate and excreted into bile or urine
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where is estrogen found in males
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quite high in seminiferous tubules (sertoli cells), other tissues by conversion of testosterone (80% total male estrogen)
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when is testosterone produced in males
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entire fetal dvlp through 10 weeks post-delivery and 10-13 years thereafter
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testosterone production at peak vs old age
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20-50% by age 80
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when does the male fetal testes begin to secrete testosterone
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~7 week embryonic life
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what causes increased metabolism with increased testosterone secretion
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likely due to anabolism of proteins
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what converts testosterone to dihydrotestosterone
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5a-reductase
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GnRH affects on LH
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LH closely follows GnRH levels, FSH follows slightly with fluctuations and changes more slowly in response to longer-term changes in GnRh
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what does FSH bind
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FSH receptors attached to Sertoli cells in seminiferous tubules
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inhibin
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secreted by Sertoli cells to inhibit FSH secretion and slight effect on GnRH
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male climacteric
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decrease in male sexual fxn
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adult eunuch characteristics
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taller (epiphyses don't unite as soon without testosterone), bones thin, muscles considerably weaker than normal man, voice child-like, no loss of hair on head, masculine hair distribution doesn't occur
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castrated adult male erection and ejaculation
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erection can occur, but with less ease; rare ejaculation can take place (semen-forming organs degenerate and loss of testosterone-driven psychic ddesire)
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adiposogenital syndrome (aka Frohlich's syndrome or hypothalamic eunuchism)
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genetic inability of hypothalamus to secrete normal amounts of GnRH; hypogonadism and obesity
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what tumors can cause a teratoma
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germinal epithelial tumors
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nervous pathway from light to pineal gland
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eyes to suprachiasmal nucleus of hypothalamus and then to poneal gland
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melatonin fxn
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decrease gonadotropic hormone secretion in anterior pituitary
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