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79 Cards in this Set

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