Nerve impulses, or action potentials, are electrical signals that travel along nerve cells. This process involves the rapid movement of ions, particularly sodium (Na⁺) and potassium (K⁺), across the nerve cell membrane through specific ion channels. The differential concentrations of these ions across the membrane create an electrochemical gradient, which, when disturbed, generates the electrical signal. Sodium ions play a critical role in the depolarization phase of the action potential.