NMJ Flashcards
(16 cards)
Choline uptake
Uses Na+ driven cotransport
Higher magnitude in CMAP means what
More motor units are working
Packaging of ACh uses what transport?
ACh/H+ antiporter
Steps in neurotransmitter release
1) voltage gated L type Ca2+ channels allow calcium in
2) calcium binds calmodulin kinase 2
3) CK2 phosphorylates synapsin
4) vesicles move along actin and bind to docking proteins
* calcium also binds to synaptotagmine, which pulls membrane apart
Why does calcium build up in post tetanic facilitation?
Calcium is removed by the slow Na/Ca antiporter
Endplate potential is based on what two things?
Time
Concentration of ACh
Which is voltage gated? EPP or MAP?
MAP
Which is a graded response? EPP or MAP?
EPP
Which does not have a refractory period? EPP or MAP?
EPP
3 ways to alter ACh synthesis
1) metabolic inhibitors (cyanide poisons mito so can’t make CoA)
2) choline deficiency
3) choline analog (hemicholiniun blocks choline uptake)
3 ways to alter ACh release
1) less Ca
2) more Mg (competes with Ca)
3) Botox (light chain is protease that breaks docking proteins)
What does curare do?
Competes with ACh for binding of receptor
Closes channel
What does succinylcholine do?
Binds receptor and causes depolarization
Reversible binding
Alpha bungarotoxin
Binds to ACh receptor and blocks ACh from binding
Alter ACh destruction
Reversible AChE inhibitors - tensilon
Irreversible AChE inhibitors - organophosphates
Regulation of ACh receptors
1) # ACh receptors
2) location
3) denervation
