How does an action potential travel across a cholergenic synapse?

An action potential arrives at synaptic knob. This causes voltage-gated Ca2+ ion channels to open, resulting in an influx of Ca2+ ions diffusing into the synaptic knob. This then causes vesicles containing acetylcholine (neurotransmitter) to fuse with the pre-synaptic membrane and release the acetylcholine. Acetylcholine diffuses across the synaptic cleft and binds to the receptor sites on the Na+ ion channels on the post synaptic membrane. This causes the Na+ channels to open and so Na+ diffuse into the postsynaptic neurone. The post synaptic neurone depolarises resulting in a new action potential.