Parturition & Lactation Flashcards

1
Q

Phase 1 Quiescence

A

prelude to birth

2nd trimester & 1st part of 3rd trimester

Uterine quiescence

No contractility

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2
Q

Phase 2 activation

A

R for OT & PGF/PGE up regulated

Ion channels activated

Connexin 43 increase

  • gap junctions
  • contractility
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3
Q

Phase 3 Stimulation

A

labor & birth

contractions

cervical dilation

delivery of fetus & placenta

Myometrium responds to uterotropic agents, oxytocin & PGs

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4
Q

Phase 4 Involution

A

Recovery

Facilitated by OT

delivery of placenta results in rapid hormone withdrawal

Uterine involution & cervical repair

Postpartum

  • lactation
  • depression
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5
Q

Uterine Activity Regulation

A
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6
Q

Oxytocin OT

A

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

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7
Q

Myotmetrial response to OT

A

Increase sensitivity to OT with increase gestation time

Changes to myometrial OT R

Up reg OT R prior to parturition

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8
Q

PG & parturition

A

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

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9
Q

FP & OTR

A

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
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10
Q

EP R

A

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
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11
Q

Pre term uterus- quiescence

A

PGE2 & progesterone

  • relax tone
  • inhibit contractions
  • PR
  • high EP2 R esp in JZ
  • low EP1/EP3

Mem bound PR

  • PGRMCs
  • high in JZ
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12
Q

Term uterus

A

Fundus & upper segments

  • decrease/loss PR
  • decrease/loss mPR
  • up reg OTR

Lower seg

  • slight increase in OTR

Cervix

  • no OTR
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13
Q

Term uterus

A

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
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14
Q

Amnion & Fetus contribute to contractility

A

EP1, EP3 & FP are up reg in amnion during labor

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15
Q

Contractile F & R gradient

A

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.

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16
Q

Parturition requires uterine relaxation

A

myometrium must relax between contractions

tonic prolonged contraction can cause uterine tetany= life threatening to fetus

As labor progress

  • increase OT & PGF
  • increase contraction intensity
  • decrease relaxation

Net= increased contractile F & decreased time between contractions

17
Q

Summary

A

PGF2 augments OT action

PGF binds to FP to cause intense smooth m. contractions throughout entire uterine body

PGF2 stim paracrine OT production

PGE contributes to smooth m. contraction, by binding to EP3 R in uterine fundus & EP1/EP3 R on amnion

PGE2 binds to EP2 R throughout uterus to reg smooth m. relaxation

PGE2 binds to EP2 & EP4 to stim relaxation of lower seg of uterus & cause relax & dilation of cervix!

18
Q

Increase estrogen may induce parturition

A

localized E:P ratio shift @ end of gestation in favor of estrogen

stim formation of myometrial gap junctions

stim PGF2a & PGE2 production

stim OT production

stim upreg of myometrial OT R

stim cervical ripening

19
Q

Intrauterine hormone

A

OT & PRL stim enz activity in decidual cells

increase hydrolysis of estrone sulfate in fetal mem

Together lead to increase production of locally acting intrauterine estrogens

local effects

  • changes due to increase local [] of estrogen
20
Q

Localized progesterone withdrawal

A

Progesterone decreases myometrial tone, increased cervical rigidity & blocks OT R

Decrease in progesterone favors myometrial activation

Progesterone withdra permits for myometrial contractions & cervical ripening

Increase PGF2a & PGE2 production

Stim upreg of MMPs - breakdown of cervical plug

21
Q

MMPs

A

Ovary, release OCCC & fibrinolysis of follicle wall

Endometrium, breakdwn functionalis & vascular remodeling

Endometerium, invasion & vascular remodel

cervix. dilation & ripening

22
Q

Labor & Delivery

A

childbirth period of onset of regular uterine contractions until expulsion of placenta

23
Q

Stage 1 labor

A

Latent phase

  • reg uterine contractions that bring dilation of cervix (2-4 cm)
  • Epidural

Active

  • rapid change in dilation to 10 cm
24
Q

Stage 2 of labor

A

starts when cervix is fully dilated to delivery of infant

increase in bloody show

desire to push

pressure on rectum

onset of nausea & vomiting

25
Q

Ferguson Reflex

A

increase in uterine stretch

cervical P trigger neuroendocrine response

+ OT feedback loop b/t uterus & post pit

Loop creates increasing levles of both local OT & systemic

Increase in OT stim production of more OT R

Until placenta delivered

26
Q

Stage 3 of labor

A

after delivery of infant- to separation & delivery of placenta

major complication is maternal hemorrhagin

27
Q

Postpartum changes

A

6-8 wks after delivery

4-6 months

Shivering

Uterine involution- 6-8 wks normal size

Cervix slightly dilated for 1 wk- returns to baseline 12-16 wks

Vaginal tone may or may not return to baseline

Av 13 lb weight loss

After 3 monhts PRL will return to normal and FSH & LH (if breastfeeding)

If not breasfeeding, PRL returns to normal 1-2 wks but no fertility until 3 monhts due to anatomy remodeling

28
Q

Hormones Postpartum

A

hCG- 2-4 wks non pregnant

FSH/LH- low for 2-3 wks after delivery

Ovarian- low until FSH/LH stabilize

Menstruation by 12th week

29
Q

hPL

A

appears to stim mammogensis

binds to PRL to stim breast dev

30
Q

Stage 1 lactogenesis

A

2nd half of preg

secretory initiation

mammary gland secrete milk

lactose, protein & immunglobin [] rise

high progesterone suppresses milk secretion

colostrum

31
Q

Progesterone & lactogenesis

A

acts on breast

PRL suppression of upreg

Block lactogenesis

PRL elevated but can’t stim lactogensis

Estrogen stim alveoli & duct deve

Estrogen stimulates colostrum

32
Q

Lactation

A

humoral & neuroendocrine mech reg lactation & milk let down are complex

Repetitive breasfeeding stim milk prod (+ feedback sys)

Lactogenesis requires PRL which is primary hormone associated w/ lactation.

Insulin, glucocorticoids (cortisol) GH & IGFs involved

Milk ejection dep on physical stimulus of suckling & OT (PRL prod)

*reg by many factors like emotional & visual*

33
Q

Stage 2 lactogenesis

A

onset of copious milk production

secretory activation

typically starts 2-3 days after delivery but may take 1 week

Progesterone withdrawal leads to onset of copious milk secretion

Blood flow, O2 & gluc uptake increase

Progesterone withdrwal & loss of PR in breast tissue permit PRL action

Maternal secretion of insulin, GH, cortisol, PTH facilitate nutrient mobilization required for milk

Breasts swell

34
Q

PRL

A

After 12 weeks:

PRL levels still increase immed after feeding

As daily feedings are red, PRL levels may fall to pre preg levels b/t feedings

35
Q

Milk production- suckling reflex arc stim PRL

A

suckling stim hypothal nuclei

TIDA neurosn inhibited & DA secretion red

increase PRL

PRL acts directly on alveolar epith cells to stim milk production

36
Q

Milk Ejection- suckling reflex arch releases OT

A

sucking stim hypothal nuke

triggers increased release of OT from post pit

Increase levels of OT act on myoepith cells lining mammary alveoli

leads to contraction of mammary alveoli & milk ejection

37
Q

Breastfeeding difficulties

A

Milk letdown problems

  1. imparied milk ejection- imparied OT release:
  • cause egorged breasts
  • leads to suckling problems
  • plugged milk ducts
  • mastitis
  1. psychological diff
  • psopartum depression/stress/irritability
  • lack of visual stimuli