parturition Flashcards
(29 cards)
how does the corpus luteum get maintained after 8 weeks
the placenta maintains the corpus luteum
how is the corpus luteum sustained 8 weeks and below
hCG
if we removed ovaries before/after 10th week, would miscarriage occur
before 6th week: yes, because corpus luteum is where P4 made and keeps P4 levels up
after 15th week: prob not, placenta makes its own P4
is it possible to get pregnant a second time while already pregnant (20 weeks in)
no, increase in P4 and E2 which feedbacks on CNS, ARC doesn’t get activated, no tertiary follicles, no LH/FSH
what is the function of P4 during pregnancy
-feeds back to keep LH/FSH low
-keeps uterine lining in tact
-prevents contraction of uterine smooth muscle
what is the function of E2 during pregnancy
feeds back to keep LH/FSH low
what 2 hormones does the placenta release
-human placental lactogen (hPL)
-relaxin
what does human placental lactogen (hPL) do
increases blood sugar; aids in preparation of milk production
what does relaxin do
connective tissue of symphis pubis (where hip bones meet) and cervix; relaxes smooth muscles of uterus
what do GABAa receptors do
gets Cl- ions in the cells, more likely to fire action potentials
what does activation of GABAa receptors do
hyperpolarizes neurons (less likely to fire APs)
numbers can be modified by cell
what activates GABAa receptors in the hippocampus
allopregnanolone (P4)
made in placenta –> goes in bloodstream –> into brain —> less excitability
when P4 levels rise, number of GABAa subunit receptors go down proportionally. why?
-when P4 levels fall (at birth), expression of GABAa subunit must increase proportionally
-need to maintain neuron excitability
what would happen if the expression of GABAa subunit did not increase sufficiently after birth
postpartum depression
what hormone stimulates the initiation of labor
increasing CRH from placenta
positive feedback loop: increase of cortisol, increases CRH
what does CRH do
- stimulates ACTH pathway in fetus
- stimulates release of prostaglandins (PG)
what do you expect would happen to a labor and delivery if there were low levels of CRH produced by placenta
early labor
how does estrogens contribute to parturition
- stimulate expression of oxytocin receptors (OXTR)
- stimulates release of prostaglandins (PG)
- soften collagen of the cervix in preparation for delivery
how does P4 contribute to contractions
-inhibits synthesis of PG and receptor expression for Oxy
-change in estrogen:P4 ratio is responsible for net activation of contraction
what would happen if a P4 antagonist (blocker) were administered to someone who is 39 weeks pregnant
initiate labor and delivery
what do prostaglandins do
initiate smooth muscle contraction
what does oxytocin do
increases strength of contraction
where is EP1 expressed
in fundus (upper) uterus
where is EP2 expressed
lower portion (nearest cervix)
