Cell body contains nucleus and other organelles of cell. Axon conducts nerve impulses away from cell body. Nervous system consists of two main divisions. Most long axons and dendrites are surrounded by neuroglial cells. Cell membranes contain myelin , an insulating lipid substance that gives nerve fibers their white color.
Outermost sheath directs path for nerve to regenerate if severed.
Inside Is Negative a. When axon is not conducting a nerve impulse, there is positive polarity outside and negative polarity inside axon membrane. Membrane is more permeable to potassium than sodium. There are also large, negatively charged proteins inside axoplasm. A rapid polarity change in membrane of a neuron results from physical stimulus, electrical shock, pH change, etc.