Topic 6 Synaptic Transmission Flashcards
How does voltage gated Ca2+ channel open and what does Ca2+ do?
Action potential arrives at synaptic know depolarises it, voltage gated calcium channel open allowing Ca2+ diffuse in (by facilitated diffusion) into synaptic knob.
Higher influx of Ca2+ into synaptic knob causes vesicle containing Acetylcholine fuse with pre-synaptic membrane.
After AcetylCholine bind fuse with pre-synaptic membrane how is voltage gated Na+ open?
When AcetylCholine fuse with pre-synaptic membrane, AcetylCholine released into synaptic cleft by endocytosis.
Acetylcholine diffuses across synaptic cleft to post-synaptic membrane and binds to complementary (Cholingeric) receptors causes Na+ channels on post synaptic membrane to open.
How is action potential causes in Synaptic transmission?
When Na+ channels open on post synaptic membrane to open Na+ diffuses into post-synaptic neurone causing depolarisation.
If threshold reached an action potential formed.
How is impulse stopped in Synaptic Transmission?
Acetylcholine removed from synaptic cleft and degraded by Acetylcholine esterase to prevent continuous impulse.
Products transferred into pre-synaptic neurone and Na+ channels close allowing post-synaptic neurone to reach resting potential.
How can cholinergic Synapse be inhibited?
Cl- move into post-synaptic neurone and K+ move out causing membrane potential reach which causes hyper-polarisation so action potential unlikely.
What is summation?
Rapid build of neurotransmitters to help generate action potential.
What is temporal summation?
1 neurone releases lots of neurotransmitters repeatedly over short time period so threshold value exceed.
What is spatial summation?
Many neurone collectively combining neurotransmitters to exceed threshold value.
What does agonists drug do?
Mimic shape of neurotransmitters and cause action potential.
How does an antagonist drug work?
Bind to receptors but block it preventing action potential.
