15.6 transmission across a synapse

Question 1

describe the transmission of an action potential in a cholinergic synapse. (6)

Answer 1

1- arrival of action potential of the presynaptic neurone causes Ca2+ ion protein channels to open & Ca2+ enters synaptic knob
2- influx of Ca2+ ions into presynaptic neurone causes synaptic vesicles to fuse with presynaptic membrane -> acetylcholine is release into synaptic cleft
3- acetylcholine diffused across synaptic cleft & bind to Na+ protein channels of postsynaptic neurone
-> Na+ protein channels open & diffuse in rapidly
4- influx of Na+ ions generate new action potential in postsynaptic neurone
5- acetylcholinesterase hydrolyses acetylcholine (to choline & ethanoic acid) & diffused/recycled back across synaptic cleft to presynaptic neurone
6- ATP (released by mitochondria) is used to recombine acetylcholine & stored in synaptic vesicles & Na+ protein channels close