Cholinergic Synapses (AQA A Level Biology): Revision Note

Synapse structure

• The junctions between cells in the nervous system are known as synapses

• The structure of a synapse includes:

  • the presynaptic cell: the neurone that carries a nerve impulse towards the synapse

  • the postsynaptic cell: the cell that receives a nerve signal at the synapse; the postsynaptic cell can be:

    • another neurone

    • an effector cell, e.g. a muscle cell

  • the synaptic cleft: the gap between the two cells

• Nerve signals are transmitted at synapses in the form of chemical signals known as neurotransmitters which:

  • are released from vesicles in the presynaptic cell

  • diffuse across the synaptic cleft

  • bind to receptors on the postsynaptic cell