A2- synaptic transmission

Question 1

Explain how a cholinergic synapse functions

Answer 1

-depolarisation of presynaptic neurone
-Ca2+ channels open and Ca2+ diffuse (facilitated) into presynaptic neurone
-causes vesicles to move downwards towards presynaptic membrane and fuse to release acetylcholine into synaptic cleft
-acetylcholine diffuses across synaptic cleft
-acetylcholine binds to receptors on postsynaptic neurone
-acetylcholine binds to Na+ gate channels in membrane causing them to open
-Na+ enter postsynaptic neurone leading to depolarisation
-when it reaches a certain threshold there’s an influx of Na+

Question 2

importance of synaptic transmission

Answer 2

in order to recycle the nt, enzymes such s AChe will hydrolyse Ach into ethanoic acid and choline to be actively transported back into presyanptic neurone > this allows the ACh to be reformed and then released > without breakdown and recycling of ACh impulses cannot reach effectors which will prevent reflex arcs > causing harm to body as ACh would be permenantly bind to posysynaptic membrane