Reproductive Physiology Flashcards
what are the functions of the reproductive system
gamete production storage nourishment transport fertilization
what is testosterone secreted by
leydig cells
what kind of receptors do sertoli cells have
FSH receptors
what do the testes produce? what do they synthesize ?
sperm and synthesize testosterone
what do sertoli cells do
aromatize testosterone to estrone (estrogen derivative) and produce androgen binding protein (weaker form of estrogen)
what kind of fluid does the prostate produce
an alkaline fluid which helps keep sperm alive in the acidic female reproductive tract
what do seminal vesicles produce
fructose and prostaglandins
what does fructose nourish
sperm
what can prostaglandin trigger
minor uterine contractions which increase movement of sperm in the female reproductive tract
how many seminiferous tubles/testicles are there
250-1000
how much sperm is produced a day
200 million
how much sperm is considered infertile
< 2,000,000
what does FSH target and promote
targets sertoli cells to promote spermatogenesis
what does LH induce
induces secretion of testostrone and other androgens by Leydig (interstitial) cells
what does GnRH induce the release of
what is it also known as
LHRH
-induces release of FSH and LH
what does testosterone enhance in mena nd women
what does it increase
what does it protect against
- enhances libido in men and women,
- increases EPO (red blood cell production)
- protects against osteoporosis
what is testosterone aromatized to
estradiol
what is the hypophyseal control of male reproduction
- LH acts on leydig cells and FSH acts on the seminiferous tubules
- inhibin inhibits FSH secretion in the pituitary
- ABP (andorgen-binding protein) makes testosterone more water soluble
what are the principle organs of the female reproductive system
ovaries, uterine tubes, uterus, and vagina
many primary oocytes die before birth, they stop in what phase until puberty
- how many are present at birth
- how many are left at puberty
prophase 1
20 milliion
200,000 left by then
the first meiotic division is completed just before ______
what is this called
-halted at what phase until fertilized
ovulation
haploid secondary cycle
-halted at metaphase 2 until fertilized
what is the primary follicle in the ovarian cycle
pre-antral
-after this point, follicles (2ndary and tertiary) are involved in production of antral fluid which surrounds the oocyte
what cells are involved in the 2ndary follicle cycle
what do they do
-many granulosa cells
convert androstenedione to estradiol via an aromatase enzyme
-stromal cells near basement membrane differentiate into theca interna and externa
what does theca interna produce
what does thec externa produce
interna: produce the androgen androstenedione, which crosses the basal lamina to get into granulosa cells surrounding the ovum, where it is converted to estradiol by an aromatase enzyme
externa: fibroblasts
what is the tertiary follicle
-what does follicular fluid have a high concentration of
aka graafian follicle
the ones that’s ovulated
-follicular fluid has high concentration of steroid hormones
what is menarche
the first cycle of puberty
what are the 4 phases of the menstrual cycle
- menses
- folicular
- ovulatory
- luteal
how long is the menses cycle
what happens here
5 days
FSH levels rise, stimulated by GnRH
how long is the follicular cycle
what hapens here
10-16 days
- FSH slowly falls while LH slowly increases
- plasma estrogens and some progestins begin to increase as follicles mature before the LH surge and peak on the day of the surge
- RISE IN LH IS DUE TO POSITIVE ESTROGEN FEEDBACK
how long is the ovulatory phase
24-48 hrs
- one day before LH surge and one day after
- progesterone cause “thermogenic shift” around time of ovulation
how long is the luteal phase and what happens here
relatively constant 14 days
-estradiol levels fall while progesterone levels increase
what do estradiol and progesterone influence
cyclic changes in reproductive tract
what are the uterine phases of cycle
- menstrual
- sloughing off of entire functional layer of endometrium - proliferative
- endometrium increases in size and thickness - secretory
- begins on day of ovulation
- glands coil and secrete carbohydrate-rich mucus - ischemic: days 27-28
- due to declining estradiol and progesterone
what atrophy in menopause
what is there a decrease and increase in
ovaries atrophy w/ few, if any, follicles
- decrease in estrogen and concomitant increase in FSH and LH
- ratio of estrogens and androgens decrease
what is estrone derived from
peripheral conversion of adrenal and ovarian androstenedione by aromatase
when the ratio of estrogen to androgens decrease what happens
- relative increase in hair growth
- breast atrophy
- vaginal dryness
- epidermal layer of skin becomes thinner and -less elastic
- hot flashes due to loss of vasomotor tone (temporary)
- osteoporosis
- increased risk of cardiovascular disease
what happens in osteoporosis
-estrogen normally antagonizes PTH effects on bone but enhances its effects on kidney, also promotes intestinal absorption of calcium
what is osteoporosis mediated by
osteoclastic factors released by T cells, normally suppressed by estorgen
why is there an increased risk of cardiovascular disease in menopause
estrogen is a coronary vessel dilator
-there is a loss of protective effects of estrogen
where does fertilization occur
ampulla of the oviduct
what implants in the uterus
blastocyte
what happens during capacitation of sperm
-increased motility and fusion of acrosomal pellet with membrane
-occurs when sperm leave inhibitory envirnoment of testes
=>acrosomal pellet uncovered
what is the acrosome reaction during fertilization
what does it contain
acrosome binds to zona pellucida
-contains hyaluronidase and protease which helps sperm break through granulosa cells
what is the fertilized egg called
zygote
-first mitotic division occurs
how is polyspermy prevented by
secretion of inhibitory factors by the ovum
when does implantation of the blastocyst occur
around day 8
-fluid filled cavity
what do most chemical tests look for during pregnancy
what does this help maintain
the prescence of beta subunit of hCG (human chorionic gonadotropin) in the blood or urine, which can be detected after implantation
-helps maintain the corpus luteum and prevent menstruation
what is the effect of estrogen during pregnancy
what is it required for
- required for develpment of fetal lungs and liver
- stimulates growth of MYOMETRIUM and mammary gland ducts and alveoli
- promotes placental breakdown of cortisol, relieving inhibition of fetal cortisol production in preparation for birth
what does progesterone do during pregnance
- maintains secretory ENDOMETRIUM
- thickens cervical mucous
- inhibits maternal immune response to fetus
- blocks uterine contraction
- inhibits lactation
why must patients be tapered off of steroid eyedrops
bc it takes time for natural cortisol production from the adrenal cortex to recover
what regulates lactogenesis
prolactin
when does lactogenesis begin
what is produced
5th month of gestation
- but only colostrum is produced
- high in carbohydrates, protein, and antibodies and low in fat
- concentrated food for small GI tract
- has laxative effect that helps clear bilirubin and prevent jaudice
what is milk ejection induced by
oxytocin
-milk letdown reflex
what does lactation reduce
- reduces FSH and LH, resulting in lactational amenorrhea
- reduced follicle formation
why pregnancy is likely during lactation
how does oral contraception prevent ovulation
reducing LH and FSH
- combination pill consisting of estrogen and progestin
- inhibits midcycle gonadotropin surge and prevents ovulation
what does oral contraception reduce the risk of? what does it increase?
- reduces risk of ovarian and endometrial cancer
- increases risk of venous thrombosis, atherosclerosis, hyperlipidemia, hypertension, and ischemic heart disease, particularly for those > 40 and smokers
- women who dont smoke have no chance of severe side effects
what is RU-486
progesterone receptor blocker
-high receptor affinity prevents progesterone from binding to its receptors and thus inhibits the action of circulating progesterone
how is RU-486 taken
-single 600 mg dose taken orally in early preg, prior to 7 wks after the onset of the last menses, terminated pregnancy in 85% of cases
what is plan B
a progesterone derivative which may prevent preg
-2 pills of 0.75 mg progestin levonorgestrel
-may prevent or delay ovulation
OR interfere w/ fertilization of an egg
OR prevent implantation of a fertilized egg in the uterus by altering its lining
how is plan B different from RU-486
it does not stop development of a fetus once the fertizlied egg implants the uterus
will not work if you are already pregnant
