The ways in which the words can be meaningfully combined is defined by the language's syntax and grammar. The actual meaning of words and combinations of words is defined by the language's semantics.
A nerve impulse is an electrical signal that travels along an axon. There is an electrical difference between the inside of the axon and its surroundings, like a tiny battery. When the nerve is activated, there is a sudden change in the voltage across the wall of the axon, caused by the movement of ions in and out of the neuron.
Example sentences containing 'nerve impulse'. Nerve impulses race up and down your body as the noise and lights of the accident intensify. Nerve impulses are picked up by probes the width of a human hair and interpreted by computers. Nerve impulses are initiated at receptor cells as a result of stimuli from the environment.