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Flashcards in Parturition and lactation Deck (39)
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define partuition

the process of giving birth labour


what two anatomical elements are key from partuition and what must happen to them

ripening of cervix and uterine contractions


outline 3 stages of labour briefly

stage 1 - ripening of cervix and developing contraction and dilation of cervix

stage 2- cervix fully dilated strong uterine contraction baby delivered head first

stage 3- extremely strong contractions delivers placenta


what hormone is extremely important in stage 3 of labour delivering the placenta

Oxytocin ensure muscle clamps down on blood vessels to prevent hemorrhage


describe the 3 time frame stages that the cervix undergoes during gestation

quiescent is for 37 weeks, activation cervix starts to ripen and weaken a bit before labour and stimulation the cervix begins to dilate


why does the cervix remain closed for majority of gestation

because a closed cervix is essential to maintaining pregancy


how is the cervix ripened

through inflammation, cox 2 enzymes stimulate prostaglandin(PGE 2) production which activates immune response, contributes to metalloproteinases 2 and 9 breaking down collagen in cervix and immune cells and cytokines attacking cervix


what does cox 2 do

enzyme for prostaglandin production


what enzyme is most important for cervix ripening

metalloproteinases 2 and 9 breaking down the collagen in the cervix


what is functional progesterone hormone withdrawal

actual concentration of progesterone does not decrease it plateaus unlike other mammals and the cells stop being responsive to progesterone


whats causes inflammatory process in cervix


HORMONE CHANGES - Functional progesterone withdrawal - inflammation and influx of
immune cells, increased corticotrophin releasing hormone and oestrogen,
plus cervical distension → oxytocin → PGR (Ferguson reflex).


what are the clinical implications of cox 2 being increased at at term
and post partum

pge 2 used to ripen cervix in women who cervix is intact and not ripening


in the quiescent stage of gestation describe uterine contraction activity and why it is favorable to be like this

minimal and this is because the baby is not ready to come out yet and strong frequent contraction for 37 weeks could harm baby


why are there does uterine contractions begin to increase

in preparation for stimulation phase where their will be many strong contractions


describe innervation and vasculrisation of myometrium

lots of vessels good supply, sparsely innervated good due to pain that would be felt potentially


what physiological changes allow preparation of uterus myometrium for labour

contraction associated proteins’
induced: prostaglandin receptor
COX-2, oxytocin receptor,
gap junctions (connexins),
calcium signalling proteins and
ion channels
Myometrium primed for contraction


for uterine contraction why is up regulation of connexons synthesis so important

so there is a greater conduction of electrical information between smooth muscles cells allowing for a more co-ordinated and strong contraction


what does cervical distension caused by fetal movement do

Cervical distension due to fetal movement and development of uterine contractile activity also triggers
maternal oxytocin release (Fergusson reflex) and local prostaglandin production.


what enzyme is responsible for PGE production



what hormones and processes cause uterine myometrium contractility to increase

The initiation of these processes is likely to involve oestrogen, oxytocin, uterine stretch, inflammatory
agents, CRH, and functional progesterone withdrawal. Clinically this information has been translated
into the use of oxytocin as an agent for labour induction and augmentation.


why is oxytocin not that useful in encouraging contractions in premature preganancy

because oxytocin receptors are poorly expressed as the stage due to down regulation as you do not want baby to be delivered early in non pathogenic circumstances


pro relaxation occurs for majority of pregnancy, what characterizes this period in smooth muscle cells

calcium in cell is low and extremely negative resting membrane potential not excitable


when are smooth muscle cells in uterus converted from pro relaxation to pro contraction

Pro-contraction pathways up-regulated in labour - Contraction in smooth muscle involved influx of
calcium through voltage gated ion channels and receptor operated channels involving the release of
inositol trisphosphate (IP3) which amplifies the response by releasing calcium from the SR


what drug can be used to inhibit uterine contraction and delay labour

nifediprine calium voltage gate inhibitior


during pregancy what happens to resting membrane potential of myometrium

becomes more and more positive from -75 to -45


prior to labour what receptor increases its protein synthesis and why

oxytocin so it is ready to respond


how does ethnicity affect when a child is born

slight variation of timing of birth with white ethnicties taking slightly longer


what is the normal time for a fetus to be born

between 37-41 weeks


why do babies in uk never exceed gestation of more than 42 weeks

medical intervention at this point


why are babies born between 37-41 weeks normally

because mother cant support growth of baby anymore, ageing placenta , balanced against fetus maturation size and ability to survive in environment makes 37-41 weeks ideal for birth