<P> Acetylcholine ( ACh ) is an organic chemical that functions in the brain and body of many types of animals , including humans , as a neurotransmitter -- a chemical released by nerve cells to send signals to other cells . Its name is derived from its chemical structure : it is an ester of acetic acid and choline . Parts in the body that use or are affected by acetylcholine are referred to as cholinergic . Substances that interfere with acetylcholine activity are called anticholinergics . </P>
which ion is needed to trigger the release of acetylcholine
an ester of acetic acid and choline