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 (see NERVOUS SYSTEM) 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.