Impulse transmission across the synapse

Impulse arrives at the pre-synaptic knob;

This causes the synaptic vesicles to move randomly within the knob;

Some vesicles make contact with the pre-synaptic membrane;

The vesicles rapture and discharge the neurotransmitter (acetylcholine) into the synaptic cleft.

The neurotransmitter diffuses across the synaptic cleft and attaches to the post-synaptic membrane.

The membrane is depolarized generating an action potential.

The action potential is then picked up by the post-synaptic neuron and transmitted as a nerve impulse along the neurone.