Flashcards in Parturition Deck (17):
_____ cells _____ in early pregnancy and _____ in later half of pregnancy
myometrial; proliferate; hypertrophy
what are the biochemical steps of uterine contraction?
myometrial action potential --> increase in intracellular calcium --> calcium binds calmodulin --> myosin light chain kinase activated --> myosin is phosphorylated --> ATP is hydrolyzed --> myosin undergoes structural change --> myosin forms a crossbridge with actin leading to contraction
labor phenotype: transition from the quiescent phase to labor phase involves a shift from _____ dominance to _____ dominance
how does progesterone maintain quiescence before labor?
inhibits intracellular calcium entry, inhibits calcium release from sarcoplasmic reticulum, membrane hyperpolarization via K+ channels, inhibits expression of contraction-associated protein genes
what is estrogen's role during the labor phase?
increases gap junctions between myometrial cells allowing for contraction synchrony between cells, increases oxytocin receptor and prostaglandin receptor expression in myometrium (contraction-associated proteins)
_____ and _____ upregulate contraction-associated proteins (CAP) in the myometrium
uterine stretch; estrogen
what are the biochemical steps of labor?
oxytocin or prostaglandins bind to their respective G protein coupled receptors --> activates phospholipase C --> stimulates release of calcium from intracellular stores --> myosin light chain kinase activation --> myosin is phosphorylated --> ATP is hydrolyzed --> myosin undergoes structural change --> myosin forms a crossbridge with actin leading to contraction
labor: oxytocin synthesized by _____ and stored in _____ increases _____ and ____ level
hypothalamus; posterior pituitary; prostaglandin; estrogen
how does the fetal adrenal gland contribute to the trigger of labor cascade?
placental oxytocin, prostaglandins, placental CRH
preterm labor: delivery before ___ weeks gestation
how does infection lead to preterm labor?
toxins produced by bacteria stimulate cytokine production leading to prostaglandin release
modifiable and non-modifiable risk factors for preterm labor
modifiable: infections and periodontal disease, smoking
non-modifiable: genetics, cervical shortening, decreased uterine space, low pre-pregnancy weight, socioeconomic disadvantage, ethnicity
name 4 therapies used to STOP preterm contractions (tocolytics) and their mechanism of action
magnesium sulfate, beta-2 adrenergic receptor agonists, calcium channel blockers (nifedipine), prostaglandin synthesis inhibitors; all prevent intracellular calcium influx
indomethacin (COX inhibitor) is also used
what therapy is used to PREVENT preterm delivery in patients with history of preterm delivery and for patients with a shortened cervix length by ultrasound?
postpartum hemorrhage: > _____ mL blood loss after vaginal delivery or > _____ mL blood loss after cesarean
postparum hemorrhage: pathogenesis, treatment
uterine relaxation/atony during 4th stage of labor; uterine massage, oxytocin, prostaglandins, ergot alkaloid (ergonovine)