pregnanc, fertility, aging, birth Flashcards
Which hormone/chemical(s) can inhibit repetitive contractions that occur in the myometrium during parturition?
A Oxytocin
B Progesterone
C K+ channel agonists
D K+ channel antagonists
E Lactate produced by glycolysis
OPTIONS B, D E
B - progesterone as hormone levels increase in pregnancy and can relax the myometrium
E- lactate during glycolysis = ACIDIC, inhibit calcium influx so contractions are weaker and longer (hypoxia same effect too
D - potassium antagonist , I THOUGHT IT WOULD INCREASE FORCE OF CONTRACTION AS THE CELL CANT REPOLARISE SO SURELY THE CONTRACTIONS WOULD INCREASE
why does female fertility decline with age?
due to the QUALITY OF OOCYTE decreasing as Oocyte aneuploidy and mitch dysfunction increase with age
what is PLC zeta?
its a sperm specific protein that can initate fertilisation by increasing the IP3 -> calcium release and osccilations seen
what is Dystocia and Atony?
forms of Dysfunctional labour
Dystocia = obstructive labour
Atony = failure of myometrium to contract
> we can use c-section to overcome this
or iv synthetic oxytocin/ prostaglandins to help with contractiosn
what is myometrium?
the smooth muscle of the uterus
its undergoes Hypertrophy and hyperplasia in the myometrium during pregnancy increasing the mass
what triggers labour?
Release of oxytocin/ increase in oxytocin receptors and
Prostaglandins – respond to stretch
activate galpha q = release of calcium needed for smooth muscle contraction
how do these prostaglandins and oxytocin induce labour?
THEY will work by propgation of an AP = voltage gated calcium influs
so need calcium osscilations to drive contractions of smooth muscle
how would potassium channel blockers affect partuition?
potassium is needed to hyperpolarise the cell or repolarise it
so if we block the potassium channels then cell can’t do this so the membrane remains DEPOLARISED FOR LONGER = stronger force of contractions
so there is continued calcium influx
which potassium channels are found in the myometrium only
potassium channel 7 and potassium channel 11
> THIS MAKES THEM EASIER TO PHARMACEUTICALLY TARGET THAN CALCIUM CHANNELS AS THEY ARE FOUND IN SPECIFIC, NOT ALL TISSUES
what type of receptor is oxytocin + prostaglandin?
well as they are involved in contractions, they must be GPCR/Galphaq
so there is PLC –Ip3–Calcium release from SR to help with contraction
HOW DOES OXYTOCIN HELP TO INDUCE LABOUR?
well it binds to its GPCR on the myometrial tissue -> galpah q so there is calcium efflux from the SR and also PKC from DAG can actuvate calcium ion channels == intracellular calcium rises —> smooth muscle contract
but also oxytocin can inhibit calcium efflux from the cell so the contraction lasts longer/ greater force
how does the myometrial tissue generate energy?
mainly though glycolysis 60-80%
so there is lots of lactate built up through anaerobic glycolysis
and lactate can inhibit calcium influx so there is weaker and prolonged contractions
how does lactate affect labour?
well lactate is an acid, so it will reduce the calcium influx into cell and reduce the contractile ability = longer and weaker contractions
> much like acidosis reducing contractile ability of heart
how does oxygen affect labour?
low oxygen/hypoxia can decline the ATP and increase the Pi which is acidic
so then will reduce calcium influx into cell, prolong the contraction as the next AP won’t fire
how does the pituitary gland develop?
there is downgrowth of the 3rd ventricle forming posterior pituitary
upgrowth of the oropharynx which is isolatd forming rathkes pouch
they interact forming the pituitary gland
