Explanation

A wave of action potential is termed as a nerve impulse. When a nerve fibre receives stimulus inside the cell, plasma membrane become positively charged with respect to outside. The change in polarity across the plasma membrane is known as an action potential. The membrane with this reversed polarity across it is said to be depolarized. The reversed polarity then passes a wave along the nerve fibre. This wave of reversed polarity or dipolarisation (action potential) moving down an axon is called a nerve impulse