• Where two neurones meet, they do not actually come into physical contact with each other – a very small gap, known as the?synaptic cleft, separates them
• The ends of the two neurones, along with the synaptic cleft, form a?synapse

A synapse

Synaptic transmission

• Electrical impulses cannot ‘jump’ across synapses
• When an electrical impulse arrives at the end of the axon on the?presynaptic neurone, chemical messengers called?neurotransmitters?are released from?vesicles?at the?presynaptic membrane
• The neurotransmitters?diffuse?across the?synaptic cleft?and?temporarily bind with receptor molecules?on the?postsynaptic membrane
• This?stimulates?the postsynaptic neurone to generate an electrical?impulse?that then travels down the?axon?of the?postsynaptic neurone
• The neurotransmitters are then?destroyed?or?recycled?to prevent continued stimulation of the second neurone, which could cause repeated impulses to be sent
• Synapses that use?acetylcholine?as a?neurotransmitter?are described as?cholinergic synapses