Neuromuscular junction Flashcards
Describe how a potential is reached in the membrane
Action potential depolarizes cell, opening calcium channels, calcium channels flood into pre-synaptic cleft releasing ACh from vescicles, Ach crosses synaptic cleft and binds to post synaptic, increasing sodium permeability causing depolarization in post synaptic terminal
Describe an end plate potential?
full depolarization of the cell
Describe minuscule end plate potential?
one random vescicle opens releasing ACh
What happens to Ach sensitivity when a nerve is denervated?
when there is damage the nicotinic receptos migrate to other areas of the cell (not just the junction) so there is increased sensitivity
What are the affects of curare?
Will bind to receptor, blocking it from accepting ACh
MEPP and EPP changes with curare?
Decreased both
What are the affects of Botulism?
Inhibit calcium from entering the presynaptic cleft. which is needed for Ach release
Mepp and Epp changes with botulism?
endplate potential is decreased, minuscule potential is unchanged
Affect of myasthenia Gravis?
antibodies block, alter or destroy nicotinic receptors
Mepp and EPP changes with MG?
decreases both
Affect of LEMS?
antibodies attack calcium channels inhibiting its release into the presynaptic cleft
Mepp and EPP changes with LEMS?
Decrease EPP, unchanged MEPP
How can you improve strength with LEMS?
Post-tetanic potentiation which is a leakage of calcium channels. which might make up for the decrease in channels caused by the disease
how can you improve strength with MG?
Anticholinesterase drug will decrease break down of Ach, so their is more circulating acetylcholine which might make up for decrease in receptors
What is the primary efferent fiber present in reflex arc?
Glutamate
