Hormone and uterine contractility Flashcards
Which hormones promote quiescence?
Progesterone and Human Chorionic Gonadotropin hormone (hCG) and CRH (corticohormone releasing hormone)
How does Connexin 43 stimulate contraction?
It produces a gap junction protein that facilitates electrical connections between cells.
Why is connexion 43 placement important?
Causes the contractions to be controlled (increase in pressure higher up to start which then moves down to the bottom of the uterus)
How do prostaglandins stimulate labour?
They facilitate depolarisation off myocytes.
How does progesterone promote quiescence?
Increases levels of cAMP which inhibits uterine contractility by preventing Calcium coming into the cell and inhibits myosin light chain kinase activity. Increased levels of cAMP (and therefore inhibition of MLCK) causes the myosin-actin cross bridge to be inhibited.
How does an increase in oestrogen (decrease in progesterone/oestrogen ratio) promote uterine activity?
Upregulation of: Gap junction activity Prostaglandin synthesis Oxytocin receptors Local oxytocin synthesis
How does a decrease in activity of cAMP pathway stimulate labour?
Causes increased influx of calcium into cells. Causes increased release of intracellular calcium. Local oxytocin synthesis
What is a local functional progesterone block?
Near the end of pregnancy progesterone levels decline. This causes decrease in gap junction protein inhibition so more gap junctions so cells can communicate more. Also there is a decrease in prostaglandin inhibition.
State the 4 overlapping phases of accelerated cervical remodelling.
- Softening 2. Effacement 3. Ripening/Dilation 4. Postpartum repair
Describe effacement
Cervix shortens and thins until it is similar thickness to surrounding myometrium when cervix begins to dilate
What is used to measure length of cervix?
Vaginal ultrasound
