childbirth Flashcards
Does high prostaglandin start labour
No. A drop in prostaglandin starts labour
What does high levels of prostaglandins in pregnancy cause?
Causes contractions
How does a muscle contraction occur?
An influx of calcium into the cell causes a chain of events that allows myosin and actin cross-bridging to occur
Explain how cervical ripening occurs
There is a reduction in collagen and increase in water, which allows the cervix to be thin and more pliable
What role does progesterone play during pregnancy
There is an increase in progesterone during pregnancy which promotes uterine quiescence (prevents contractions and has anti-inflammatory effects)
What happens to progesterone levels when approaching full term?
They drop off. This is essential for labour, but is not enough to actually cause labour
Where is CRH released from in pregnancy?
The placenta
Levels of CRH binding proteins increase or decrease approaching full term? What effect does this have?
Binding protein levels decrease, meaning more of the hormone is free and available to bind to its receptor
How does the CRH receptor change when you approach full term?
The CRH receptor typically promotes uterine relaxation, however as you approach full term, the receptor changes to promote contractions (converts to the contractile state)
Name 3 areas where oxytocin is synthesised
Posterior pituitary, uterine lining and placenta
High CRH stimulates production of what from the adrenal gland?
Cortisol
High cortisol stimulates a positive feedback loop, where the placenta increases production of which two molecules?
CRH and estrogen
Name the effects of cortisol on prostaglandins in child birth?
Cortisol promotes the production of prostaglandins which causes an increase in uterine contractions.
Increased prostaglandin release causes an increase in…
Oxytocin release and also causes up regulation of oxytocin receptors
Two molecules that are unregulated to allow for uterine contractions?
Prostaglandins and oxytocin
PGF2a is the prostaglandin responsible for…
Acts on the uterine myometrium to tighten gap junctions and increase depolarisation
Which prostaglandin increases vasodilation to ensure there is good blood flow during child birth?
PGI
Which prostaglandin facilitates cervical ripening by degrading cervical collagen
PGE2
What effect does an increase in cortisol have on the foetus
It acts on the lungs of the baby to increase breathing movements and increases lung surfactant production
Main use of tocolytics?
Prevention of preterm labour
What drug class does nifedipine belong to?
It is a tocolytic
Explain the MOA of nifedipine
It is a calcium channel blocker, and therefore prevents contractions.
How does indomethacin work as a tocolytic
It prevents prostaglandin synthesis
Define oxytocics
Drugs used to induce labour, enhance contractions and prevent postpartum haemorrhage
