The electrical charge that travels along the motor neuron is
caused by depolarization. Depolarization is caused by the inflow of Na+ ions into the neuron. At the neuromuscular junction, depolarization causes Ca2+ ions
to enter the post-synaptic neuron. Binding of Ca2+ to sensor protein in the neuron causes the neuron to
release neurotransmitter acetylcholine into the synaptic cleft. The neurotransmitter binds to ionotropic receptors on the sarcolemma of the muscle fiber
causing contraction of the muscle fiber.
