Neurally evoked transmitter release Flashcards
what ion is essential for neurally evoked neurotransmitter release
calcium
how quick is calcium triggering of vesicle fusion
0.1 ms
what ion blocks the voltage gated calcium ion channel
Mg
what does Mg block
voltage gated calcium ion channel
what does a high Mg and a low Ca extracellular solution reduce
epp to below threshold for firing an action potential
release of neurotransmitter at the NMJ is
quantal
how do you measure quantal content
mean epp amp /mean mepp amp
what does each quanta give a rise to
via what
mepp
activation of nicotinic ACh receptors
the ampltidue of a mepp is influenced by whatt
the number of NAChR receptors stored in the vesicle
mepps summate to give what
an epp
which initiate an action potential
-> muscle contraction
what does dendrotoxin block
voltage gated K+ channels
what does dendrotoxin do to the quantal content
EPP increased
Mepp no change
therefore, increases quantal content
what is tubocurarine
a non-depolarising neuromuscular blocker
where does tubocurarine compete
ACh to skeletal muscle nicotinic ACh receptors
what does tubocurarine do to the action potential
reduces the amplitude of the epp to below the threshold for muscle fibre action potential
what does tubocurarine do to the quantal content
no change as decreases both mepp and epp
tubocurarine acts post synaptically to block what
nicotinic ACh receptors
what does botulinum toxin do to quantal content
decreases quantal content
decreases epp but not change to mepp
where does botulin toxin work
pre synaptically
why does botulin toxin work pre synaptically
decrease naturally evoked ACh release
what does botulin inhibit
action potential evoked vesicular release
how does the toxin enter the dendrite
by endocytosis
