Synaptic transmission

• What is a cholinergic synapse?


  One where the neurotransmitter is acetylcholine
• What happens when the action potential arrives at the pre-synaptic knob?

  Calcium ion channels open and calcium ions enter via facilitated diffusion
• What do calcium ions cause?


  The synaptic vesicles to fuse with the pre-synaptic membrane, releasing acetylcholine into the synaptic cleft
• Why do acetylcholine molecules travel quickly across the synaptic cleft?

  Short diffusion pathway
• What happens when the acetylcholine arrives at the post-synaptic knob?

  Binds to receptor sites on sodium ion channels, so they open allowing sodium ions to diffuse in
• What does the influx of sodium ions do?

  Creates an action potential
• What happens to remaining neurotransmitters?

  Reuptake
• What is the process of reuptake?

  Acetylcholinesterase hydrolyses acetylcholine into acetyl and choline. These diffuse back across the synaptic cleft and into the pre-synaptic neurone
• How is acetylcholine reformed?


  ATP combines acetyl and choline back to acetylcholine, which is stored in synaptic vesicles