At a cholinergic synapse, calcium influx triggers acetylcholine release, which diffuses across the cleft, binds to postsynaptic receptors, and is then broken down by enzymes.
At a cholinergic synapse, arrival of an action potential causes calcium influx, triggering acetylcholine release into the synaptic cleft. Acetylcholine binds to postsynaptic receptors, potentially causing depolarization and a new action potential, after which it's broken down by enzymes.
| Front | Stages for cholinergic synapse |
|---|---|
| Back | Action potential arrives at synaptic knob of the presynaptic neurone Action potential stimulates voltage gated calcium ion channles in presynaptic neurone to open Calcium ions diffuse into synaptic knob Influx of calcium ions in synaptic knob causes synaptic vessicles to move to presynaptic membrane and then fuse with presynaptic membrane Vesicles release neurotransmitter acetylcholine into synaptic cleft (exocytosis) acetylcholine diffuses across synaptic cleft into postsynaptic membrane Depolarisation of membrane occurs action potential on postsynaptic membrane produced if threshold reached Acetylcholine is removed from synaptic cleft so response doesn't keep happening, enzyme breaks down acetylcholine and products are re-absorbed by presynaptic neurone and used to make more acetylcholine |
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