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The release of neurotransmiter begins when action potentials (= electro-chemical impulses) arrive at the terminal branches of a motor neuron.
Ca2+ channels in the synaptic knobs open in response, and Ca2+ ions diffuse into the neuron.
The influx of Ca2+ causes several of the synaptic vesicles to fuse with the neuron membrane and release acetylcholine (= ACh) molecules are into the synaptic cleft.
Thousands of ACh molecules diffuse across the synaptic cleft and many bind to receptors embedded in the motor end plate of the muscle fiber.
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