Acetylcholine, a neurotransmitter that is involved in various functions in the body, it is the chief neurotransmitter at the neuromuscular junction and plays a crucial role in cognition, movement control, perception, mood and various other neurological functions. It is biosynthesized from choline, an essential B group vitamin. See below for their structures. It binds to two distinct families of receptor: the nicotinic acetylcholine receptors (nAChRs), which are excitatory ionotropic receptors found primarily in the CNS, adrenal medulla and neuromuscular junction and the muscarinic acetylcholine receptors (mAChRs) which are metabotropic receptors found primarily in the PNS and CNS. nAChRs comes in various subunits, which are expressed in different tissues of the body.