AP goes down motor neuron to synaptic end bulb.
When it gets to the end, instead of opening up voltage reg sodium channel, it's going to open voltage reg calcium channel.
Because calcium conc is greater outside of cell, calcium will flow into the synaptic end bulb.
Calcium activates microtubules that will lead to exocytosis of synaptic vesicles. Synaptic vesicles contain acetylcholine (Ach)
Ach is dumped into the synapse and diffuses across the synaptic cleft.
Ach binds to ligand gated na channel.
sodium rushes into muscle cell...depolarization. Channel allows both sodium and potassium to move. Sodium will move in and potassium will move out. Since sodium moves more, net charge is +1 inside and the cell is depolarized. More sodium moves in because of size (sodium is much smaller than potassium). Even though potassium concentration is greater than sodium concentration, more sodium move than potassium because of electrical gradient. Inside of cell is -70 and outside is 0. Opposites attract. Negativity of inside of cell is trying to pull sodium into cell and hold onto potassium and keep it from leaving the cell. Electrical gradient much more important than chemical gradient.
Muscle cell is depolarizes to -55 mV which will cause voltage gated activation sodium gates to open and fire off an action potential. Action potential starts over again but now in the muscle cell.
action potential occurs. all the steps of an action potential happens.
AChE breaks down ACh closing ligand gated Na+ gates stopping generation of more action potentials