An electrochemical impulse which is transmitted by nerve cells.
Transmission of stimuli to or from the central nervous system.
The electrical activity in the membrane of a neuron that, by its rapid spread from one region to the next, is the means by which information is transmitted within the nervous system along the axons of the neurons. The membrane of a resting nerve is charged (polarized) because of the different concentrations of ions inside and outside the cell. When a nerve impulse is triggered, a wave of depolarization spreads, and ions flow across the membrane. Until the nerve has undergone ‘repolarization no further nerve impulses can pass.
This is transmitted chemically, by the formation at nerve-endings of chemical substances. When, for example, a nerve to a muscle is stimulated, there appears at the neuromuscular junction the chemical substance, acetylcholine. Acetylcholine also appears at endings of the parasympathetic nerves and transmits the effect of the parasympathetic impulse. When an impulse passes down a sympathetic nerve, the effect of it is transmitted at the nerve-ending by the chemical liberated there: adrenaline or an adrenaline-like substance.
A self-propagated electrical signal transmitted along the membrane of a nerve. At the end of the axon of the nerve, the electrical impulse stimulates the release of a neurotransmitter, which may stimulate or inhibit another electrical impulse in another nerve fiber, cause muscle contraction or glandular secretion, or produce a sensation in the brain. The velocity varies according to the diameter of the fiber and the presence or absence of a myelin sheath. The most rapid conducting mammalian neurons (50 to 80 m/sec) are large, myelinated neurons.