Cholinergic Synapse

• How is a nerve impulse transmitted across a cholinergic synapse?


  1. An AP arrives at the synaptic knob of the presynaptic neurone
  2. The AP stimulates voltage-gated CALCIUM ion channels in the presynaptic neurone to open
  3. CALCIUM IONS DIFFUSE into the synaptic knob (pumped out afterwards by ACTIVE TRANSPORT)
• How is a nerve impulse transmitted across a cholinergic synapse?


  4. The influx of calcium ions into synaptic knob causes the synaptic vesicles to move to the presynaptic membrane. they then FUSE with the PRESYNAPTIC MEMBRANE

  5. the vesicles release ACh (neurotransmitter) into the synaptic cleft - this is EXOCYTOSIS
• How is a nerve impulse transmitted across a cholinergic synapse?

  6. ACh diffuses across the SYNAPTIC CLEFT and binds to SPECIFIC cholinergic receptors on the postsynaptic membrane

  7. This causes sodium ion channels in the postsynaptic neurone to open
• How is a nerve impulse transmitted across a cholinergic synapse?


  8. The influx of sodium ions into the postsynaptic membrane causes DEPOLARISATION. An AP on the postsynaptic membrane is generated IF THRESHOLD is reached
• How is a nerve impulse transmitted across a cholinergic synapse?


  9. ACh is removed from the synaptic cleft so the response does not keep happening

  • ACh broken down by enzyme AChE and the products are RE-ABSORBED by the presynaptic neurone and used to make more ACh
• ACh is a what?


  neurotransmitter
• AChE is a what?


  enzyme
• What is AChE?


  Acetylcholinesterase
• What is ACh?


  acetylcholine