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The contractions are responsible first for dilating the cervix, moving the foetus through the pelvis and eventually expelling the baby. The primary hormone involved is oxytocin, a protein (9 amino acids long) which is released following a nervous response which results from the weight of the baby on the cervix, among other things.
The contractions are responsible first for dilating the cervix, moving the foetus through the pelvis and eventually expelling the baby. The primary hormone involved is oxytocin, a protein (9 amino acids long) which is released following a nervous response which results from the weight of the baby on the cervix, among other things.
Oxytocin stimulates the decidual layer to release prostaglandins (which in turn enhance the effect of oxytocins). These act on the myometrium to produce a contraction by:
Oxytocin stimulates the decidual layer to release prostaglandins (which in turn enhance the effect of oxytocins). These act on the myometrium to produce a contraction by initiating the release of contraction associated proteins (CAP's) which:
* increasing gap junctions between cells to increase the effectiveness of the synctium and increase the likelihood that an action potential will occur
* increasing gap junctions between cells to increase the effectiveness of the synctium and increase the likelihood that an action potential will occur
* increasing ion channels for calcium to increase the effect of an action potential
* increasing ion channels for calcium to increase the effect of an action potential
* increasing oxytocin and prostaglandin receptors to enhance the above two effects
* increasing oxytocin and prostaglandin receptors to enhance the above two effects
Calcium induces the production of myosin light chain kinase, which in turn induce contractions.
Calcium activates myosin light chain kinase, which in turn induce contractions.
A high estrogen:progesterone ratio is required for contractions, as this results in an increase in the release of prostaglandins (by stimulating the release of phosphorlipase from lysosomes) and increasing the number of oxytocin receptors.