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20 Cards in this Set

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  • Back
What are the main functions of the high estrogen and progesterone during pregnancy?
maintain endometrium for fetus, suppress ovarian follicle development, stimulate development of breasts
Fertilization takes place within how many hours of ovulation?
24hrs (usu in ampulla of fallopian tube)
When does fertilized blastocyst arrive and implant in uterine cavity?
arrives ~4 days after ovulation, implants ~5 days after ovulation
At the time of implantation, what does the blastocyst consist of?
inner cell mass (becomes fetus), trophoblast (outer rim) (becomes fetal contribution of placenta), blastocyst cavity, zona pellucida (which gets broken down)
What component of the blastocyst is responsible for invasion/implantation in the endometrium?
syncytiotrophoblast develops finger-like projections into the endometrium, forms a sponge-like network of spaces (lacunae) that connect directly to maternal vessels
What is responsible for the "rescue" of the corpus luteum, and when does this occur?
the trophoblast secretes HCG (human chorionic gonadotropin) ~8 days after ovulation (thus corpus luteum continues to produce estrogen/progest)
How is progesterone produced in the 2nd and 3rd trimesters?
produced by placenta: cholesterol enters placenta from maternal circulation -> pregnenolone -> progesterone
What is the major placental form of estrogen?
How is estriol produced in the 2nd and 3rd trimesters?
*interplay of mother, placenta, and fetus*

cholesterol (in placenta)-> pregnenolone -> enters fetal circ -> (in fetal adrenal cortex) DHEA-sulfate -> (in fetal liver) -> 16-OH DHEA-sulfate -> (back to placenta) converted to estriol
What type of contractions often occur 1 month before partuition?
Braxton Hicks contractions (uncoordinated contractions due to distention)
What is the role of the estrogen/progesterone ratio in initiation of partuition?
ratio increases near term
estrogen decreases threshold for contractile stimuli, and stimulates prostaglandin production (increase intracell Ca of uterine smooth muscle, thus inc contractility)
What is the role of oxytocin in partuition?
still unknown; oxytocin receptors up-regulate near term, and dilation of cervix stimulates oxytocin; is used to induce labor
What are the 3 stages of labor?
1) uterine contractions progressively widen and thin cervix
2) fetus is delivered
3) placenta is delivered, and powerful contractions constrict uterine blood vessels to minimize bleeding
Why is there no lactation during pregnancy?
estrogen and progesterone promote breast development and (est) stimulates prolactin s/c, but inhibit prolactin action
What stimuli maintain lactation?
suckling, which stimulates lactation and oxytocin s/c
What are the secondary effects of prolactin?
*inhibits ovulation*
(inhibits GnRH, thus inhibits LH/FSH, and antagonizes LH/FSH action on ovaries)
How do oral contraceptives work?
estrogen and progesterone exert negative feedback on LH/FSH -> prevent ovulation and affect cervical mucus and tubal mobility
How does the morning after pill work?
mifepristone (RU 486) = antagonist to progesterone receptor -> prevents implantation
What are the hormone changes that occur at menopause?
gradual decrease in estrogen, removes feedback inhibition, and thus FSH/LH increase
What are the common symptoms of menopause?
thinning of vaginal epithelium, decreased vaginal secretions, decreased breast mass, accelerated bone loss, vascular instability (hot flashes), and emotional lability

(caused by loss of ovarian source of estrogen)