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 . Acetylcholine is the neurotransmitter used at the neuromuscular junction -- in other words , it is the chemical that motor neurons of the nervous system release in order to activate muscles . In the brain , acetylcholine functions as a neurotransmitter and as a neuromodulator . A receptor antagonist is a type of receptor ligand or drug that blocks or dampens a biological response by binding to a receptor rather than provoking the response like an agonist .
Acetylcholine induces neuromodulation by binding to receptors.