Neuromuscular Junction

Question 1

Define Motor end plate

Answer 1

Where one axon acts on muscle

Question 2

What is the fate of ACh

Answer 2

Hydrolysed by Acetylcholinesterase into choline which is taken up by choline carrier and acetate which diffuses through membrane

Question 3

Why is ACh binding to nACHr for a long time bad

Answer 3

Further AP thus contraction generated independent of whats going on in motor neurone

Question 4

What is the sequence of events at NMJ

Answer 4

AP invades terminal bouton
Ca2+ moves down conc gradient into pre synpatic terminal via VG gated channels
Ca2+ bind to Synaptotagmin, energy from conformational change drives vesicle fusion
ACh released by exocytosis, diffusion across cleft and bind to nAChr
Na+/K+ channel open. Na+ influx > K+ efflux to make End Plate potential more positive
EPP > threshold. AP initiated. VG open
AP invades T tubules
DHP receptor senses change in voltage and releases Ca2+ via channel into sarcoplasm