synaptic transmission - cholinergic synapses

Question 1

arrival of an action potential

Answer 1

• arrives at synaptic knob of presynaptic neurone
• AP stimulates voltage-gated ion calcium ion channels to open
• calcium ions diffuse into the synaptic knob

Question 2

fusion of the vesicles

Answer 2

• influx of calcium ions into the synaptic knob causes synaptic vesicles to fuse with presynaptic membrane
• vesicles release acetyle choline into the synaptic cleft by exocytosis

Question 3

diffusion of ACh

Answer 3

• ACh diffuses across the synaptic cleft and binds to specific cholinergic receptors on the post synaptic membrane
• this causes sodium ion channel in the postsynaptic membrane to open
• influx of sodium ions causes depolarisation
• AP on post synaptic membrane is generated if threshold is reached
• ACh removed from the synaptic cleft, so the response doesn’t continue happening
• broken down by acetylecholinesterase and products are reabsorbed by presynaptic neurone and used to make more ACh.