AQA A Level Biology复习笔记6.2.7 Cholinergic Synapses

• 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