1) Action potential is transmitted to presynaptic neurone end, 2) depolarisation of presynaptic membrane causes Ca^2+ voltage gated channel proteins to open
3) Ca^2+ ions diffuse through voltage-gated channels into synaptic bulb, 4) Ca^2+ ions stimulate synaptic vesicles (with about 10,000acetylcholine) to move towards presynaptic membrane
5) Vesicles fuse with presynaptic membrane and release acetylcholine into synaptic cleft, by exocytosis, 6) They diffuse across synaptic cleft and bind to receptor sites on Na+ channel proteins in postsynaptic membrane
7) Before ACh binding, postsynaptic membrane is polarised and has resting potential, 8) When ACh binds to receptor sites, Na+ channels open (can change shape) and Na+ ions diffuse into postsynaptic neurone
9) Na+ ion influx depolarises postsynaptic membrane, causes excitatory postsynaptic potential, 10) Acetylcholine leaves ion channels and enters acetylcholinesterase enzyme active sites very quickly, into ethanoic acid and choline so stimulation is brief
11) Prevents continued action potential production on postsynaptic membrane, 12) Choline molecules re-enter presynaptic neurone and are re-synthesised into acetylcholine by ATP and stored in vesicles
9) Na+ ion influx depolarises postsynaptic membrane, causes excitatory postsynaptic potential, 10) Acetylcholine leaves ion channels and enters acetylcholinesterase enzyme active sites very quickly, into ethanoic acid and choline so stimulation is brief
Cholinergic synapses use acetylcholine (Ach) as their neurotransmitter
