M&R Session 5- The Cellular Response To Action Potentials Flashcards
Why does a small amount of calcium influx cause a significant increase in intracellular calcium?
Because basal intracellular concentrations of calcium are so low.
What is the result of an AP reaching a presynaptic membrane?
Causes the opening of voltage gated calcium channels and a calcium influx.
What does the entry of calcium trigger?
Neurotransmitter release
What is the structure of voltage gated calcium channels?
Similar to voltage gated sodium channels. 6 transmembrane domains in each of the 4 subunits.
How do we know that calcium channels have structural diversity?
Because they have different blockers.
What is the advantage of blockers being specific to few calcium channels?
They allow more localised effects.
What are the specific blockers to the L type calcium channel?
Dihydropyridines
Describe how the influx of calcium causes acetylcholine release.
The influx of calcium binds to synaptotagmin.
The vesicle is brought closer to the membrane.
The snare complex makes a fusion pore, which ACh can move out of.
How is an end plate potential produced?
The released acetylcholine binds to nicotinic acetylcholine receptors on the post synaptic membrane and produces an end plate potential.
How many acetylcholine bind to nAChR to open it?
2
Where do competitive acetylcholine blockers bind?
To the acetylcholine recognition site.
Give an example of a competitive blocker.
Tubocurarine
What do depolarising blockers do? What is the consequence for sodium channels?
They cause maintained depolarisation at the post synaptic membrane.
They become inactivated due to accommodation.
Give an example of a depolarising blocker.
Succinylcholine
