What happens at neuromuscular junctions?
A wave of depolarisation is sent toward the neuromuscular junction, this causes voltage gates Ca2+ channels in the presynaptic membrane to open allowing the Ca2+ ions to enter following their concentration gradient. An influx in Ca2+ concentration in the presynaptic knob causes vesicles containing acetylcholine (a neurotransmitter) molecules to fuse with the membrane, releasing them through exocytosis. On the surface of the post synaptic membrane there are complementary, membrane bound proteins called acetylcholinesterases, that the neurotransmitters bind to causing a wave of depolarisation to occur in the post synaptic membrane which travel down T-tubules deep into the muscle tissues to elicit a contraction through the sliding filament theory.
