Nerve tissue and nerve fibers are composed of neurons or nerve cells. Using an unlabeled diagram of a neuron,the main structures are labeled and described as to function. These include the cyton, nucleus, dendrites, axon, myelin sheath, nodes, and terminal branches. The myelin sheath's importance in protection of the neuron and prevention of "short circuit" of impulse was stressed by describing some auto immune disorders, like multiple sclerosis which occurs. We researched a few others, like ALS to show the effect on muscles and paralysis of muscles.