Please Write down the basic function or key feature of the structures in the list: motor unit, Schwann cell/myelin, neuromuscular junction, motor neuron/terminal, junctional fold, synapse, synaptic vesicle with ACh, nicotinic ACh receptor, Na voltage-gated channel, myofibril, sarcomere, Z-disc, I-band, A-band, H-band, M-line, thick myofilament, myosin, thin myofilament, actin, troponin, tropomyosin