Explain the transmission of nerve impulses across a cholinergic synapse

When an action potential arrives at the pre-synaptic neurone, it causes a change in voltage due to the presence of positive Na ions. This causes voltage-gated Ca 2+ protein channels to open and allow calcium ions to move into the pre-synaptic neurone. This causes the synaptic vesicles containing the neurotransmitter acetylcholine to move towards the membrane of the pre-synaptic neurone, fusing with the membrane and releasing acetylcholine into the synaptic cleft. Acetylcholine binds to complementary receptors on the post-synaptic neurone's membrane causing neurotransmitter gated Na+ ion channels to open. Na+ ions move into the post synaptic neurone, triggering an action potential once the threshold value has been reached. Acetylcholinesterase hydrolyses acetylcholine into choline and ethanoic acid, which diffuses back into the presynaptic neurone where ATP then recombines acetylcholine and it reforms in a synaptic vesicle; Na+ ion channels close in the absence of acetylcholine at receptor sites.