AQA A Level Biology

Revision Notes

6.2.7 Cholinergic Synapses

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, IGCSE & GCSE Biology revision notes

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

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Lára graduated from Oxford University in Biological Sciences and has now been a science tutor working in the UK for several years. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning.

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