A word is one or more sounds that in combination have a specific meaning assigned by a language. The symbolic meaning of words can be so powerful that people are willing to risk their lives for them or take the lives of others.
A nerve impulse is the relaying of a coded signal from a nerve cell to an effector (a muscle cell, a gland cell or another nerve cell) in response to a stimulus. It is the means by which a nerve cell communicates with another cell.
A nerve impulse begins conduction as electrical impulses, initiated by the brain, travel down through nervous system cells. The electricity causes a change in polarity by opening channels to move positive sodium or potassium ions in or out. Positive molecules are stored in membranes guarded by gated channels.