parturition Flashcards
hallmark of phase 1
uterine quiescence
functions of cervix during pregnacy
protects repro tract from infx
maintains cervical competence
inc in tissue compliance
phase 2 endometrium
inc oxytocin & CAP receptors
inc responsiveness to uterotonic agents
phase 2 cervix
collagen breakdown, CT change
proteoglycans, GAGs, fibroblast
inc in inflamm cells
phase 2 endocervical glands
hyperplasia, inc mucus
what can be done to delay cervical opening, softening, dilatation, and effacement?
inhibition of prokinase enzymes
progesterone
cervical cerclage
what can be done to inc cervical opening, softening, dilatation, and effacement?
PGE2 and PGF2 alpha
progesterone antagonist
first stage of labor starts & ends when?
latent phase until deceleration
latent phase uterine contractions
mild contractions
latent phase cervix
“show”, mucus plug is rmeoved w/ some blood from the cervix
causes of labor pain
hypoxia
compression of nerve bundle in paracervical area (cervical dilation)
peritoneum is contracted (fundal stretching)
differentiate physiologic ring from pathologic ring
physio: upper highly contracting active segment & lower dilating passive segment
patho: contractions are stronger & the thinning out is more prominent
explain fetal descent in terms of station
basis is maternal ischial spine
above is negative, below is positive
what is engagement?
fetal head enters into pelvis
biparietal diameter transverse pelvic inlet
what happens to pelvic floor during labor?
levator ani muscle closes the lower end of pelvic cavity like diaphragm
what happens to levator ani muscle
hypertrophy
fibers will stretch and accommodate fetal head
what is stage 3?
delivery of placenta & membrane
what induces delivery of placenta?
dec intrauterine volume, myometrium contracts & induces placenta separation
3 general theories describing labor initiation
fxal loss of pregnancy maintenance factors
synthesis of factors that induce parturition
mature fetus
advantages of SM qualities for uterine contraction & fetal delivery
degree of SM cell shortening
forces can be exerted at multiple directions
SM is not organized in same manner as skeletal muscle
greater multidirectional generation in uterine fundus vs lower uterine segment
serves primarily as a protective tissue providing immunological acceptance
chorion laeve
low intensity, brief myometrial contractions during quiescent phase normally not causing dilation
braxton-hicks contractions
quiescence is achieved by
diminished intracellular crosstalk & reduced intracellular Ca level
activation of uterine ER stress-unfolded protein response
uterotonin degradation
contractility results from
enhanced interactiond bet. myosin & actin
heightened excitability of indvl myometrial cell
promotion of intracellular crosstalk
shape of actin during relaxation & contraction
R: globular
C: filamentous
actin-myosin interaction
ca binds to calmodulin w/c binds & activates MLCK w/c phosphorylates light chain of myosin
coupling of actin & myosin activates ATPase w/c generates force
BKca channel during relaxation & contraction
R: enhance BKca channel opening
C: inhibit BKca channel opening
how does progesterone maintains uterine quiescence?
lowers the CAPs
prolongs ERSR w/c promotes caspase 3 activation
GPCR promoting relaxation by inc cAMP
beta adrenergic receptors LH & hCG receptors PG E2 & E4 relaxin CRH (Gs-adenylate cAMP) PTHrP (Gs-adenylate cAMP)
what is lightening?
fetal head oftentimes descends to or even through the pelvic inlet
“baby dropped”
action of estradiol & progesterone on oxytocin receptor?
E: inc myometrial oxytocin receptor
P: enhance oxytocin receptor degradation
overview of changes in cervical ripening
dec in collagen bundles
inc HA
dec dermatan sulfate
inc cytokines
fetal contributions to parturition
uterine stretch fetal endocrine cascade (CRH) dec fetal lung surfactant & inc PAF fetal membrane senescene fetal anomalies & delayed parturition
1st stage of labor
cervical effacement & dilation
ends when cervix is fully dilated (10cm)
2nd stage of labor
fetal expulsion
begins from full cervical dilation and ends in fetal expulsion
3rd stage of labor
placental separation & expulsion
begins w/ delivery of fetus and ends with stage of placental separation & expulsion
dependable sign of impending onset of active labor
show or bloody show
this is defined as mechanical dilation of cervix w/c can be d/t release of oxytocin or PGF2 w/c induce uterine contraction
ferguson reflex
pressure exerted by the dec in horizontal diameter producing straightening of fetal vertebral column and this presses the upper pole of fetus firmly against the fundus whereas the lower pole id thrust farther downward and into the pelvis
fetal axis pressure
this phase is variable and sensitive to chnages in extraneous factors and by sedation and myometrial stimulation
latent phase
predict the outcome of labor
acceleration phase
good measure of over-all efficiency of uterus
phase of maximum slope
reflective of feto-pelvic relationship
deceleration phase
descent pattern of normal labor
hyperbolic curve
in G0P0, engagement is accomplished before labor begins & further descent does not occur until late in labor, T or F?
true
gold standard for rates of cervical dilation & fetal descent during active labor
friedman’s curve
sequence of 3rd stage of labor
separation of amniochorion
placental separation
placental extrusion
differentiate schultze from duncan mechanism
S: central; fetal surface
D: peripheral; maternal surface
uterotonins in parturition phase 3
oxytocin
PG
endothelin-1
angiotensin II
phase 4
puerperium
