Parturition & Lactation Flashcards
Phase 1 Quiescence
prelude to birth
2nd trimester & 1st part of 3rd trimester
Uterine quiescence
No contractility
Phase 2 activation
R for OT & PGF/PGE up regulated
Ion channels activated
Connexin 43 increase
- gap junctions
- contractility
Phase 3 Stimulation
labor & birth
contractions
cervical dilation
delivery of fetus & placenta
Myometrium responds to uterotropic agents, oxytocin & PGs
Phase 4 Involution
Recovery
Facilitated by OT
delivery of placenta results in rapid hormone withdrawal
Uterine involution & cervical repair
Postpartum
- lactation
- depression
Uterine Activity Regulation
![](https://s3.amazonaws.com/brainscape-prod/system/cm/029/431/718/a_image_thumb.png?1659404533)
Oxytocin OT
Potent uterotonic agent
OT induced uterine contractions identical to endogenous ones
Uterine contractions can be induced w/ electrical stim of post pit or manual stim of nipple
OT R antagonist- competitive Inhibit labor
Atosiban inhibit preterm labor
Myotmetrial response to OT
Increase sensitivity to OT with increase gestation time
Changes to myometrial OT R
Up reg OT R prior to parturition
PG & parturition
COX inhibitors- inhibit myometrial contractility
Exogenous delivery of PGF2a & PGE2 stimulates uterine contractility in women
PG increase during labor!
COX2 upreg in myometrium & cervix just prior to parturition
FP & OTR
FP
- GPCR
- smooth m. contraction
- vasoconstriction
- vasuclar smooth m. hypertrophy
- stim Ca2+ mobilization
OTR
- smooth m. contraction
- inhibited by progesterone
- mRNA up reg by estradiol
- stim Ca2+ mobilization
EP R
EP1 & EP3
- smooth m. contraction
- vasoconstriction
- EP1 Ca2+ mobilization
- EP3 decrease cAMP
- in upper fundus
EP2 &EP4
- smooth m. relax
- vasodilation
- stim adenylate cyclase
- stim cAMP production
- on the cervicx
Pre term uterus- quiescence
![](https://s3.amazonaws.com/brainscape-prod/system/cm/029/434/105/q_image_thumb.png?1659432260)
PGE2 & progesterone
- relax tone
- inhibit contractions
- PR
- high EP2 R esp in JZ
- low EP1/EP3
Mem bound PR
- PGRMCs
- high in JZ
Term uterus
![](https://s3.amazonaws.com/brainscape-prod/system/cm/029/435/191/q_image_thumb.png?1659432260)
Fundus & upper segments
- decrease/loss PR
- decrease/loss mPR
- up reg OTR
Lower seg
- slight increase in OTR
Cervix
- no OTR
Term uterus
![](https://s3.amazonaws.com/brainscape-prod/system/cm/029/435/599/q_image_thumb.png?1659432261)
Outer myometrium
- up reg FP
fundus
- up reg EP3
- up reg FP
upper seg
- up reg EP3
- up reg FP
Lower seg & cervix
- up reg EP4 & high level EP2
- lower FP level
Amnion & Fetus contribute to contractility
![](https://s3.amazonaws.com/brainscape-prod/system/cm/029/435/745/q_image_thumb.png?1659432261)
EP1, EP3 & FP are up reg in amnion during labor
Contractile F & R gradient
![](https://s3.amazonaws.com/brainscape-prod/system/cm/029/435/838/q_image_thumb.png?1659432261)
smooth m. contractile OTR, FP & EP3 R are highest in fundus & upper seg of uterus
Strong contractions
Smooth m. relaxant EP2/EP4 are higest in lower seg & cervix.
Relaxation
Strong contractions initiated in fundus & radiate to cervix.