Cholinergic transmission involves the synthesis of acetylcholine (ACh) from choline and acetyl-CoA by the enzyme choline acetyltransferase (ChAT). ACh is stored in synaptic vesicles and released into the synaptic cleft upon neuronal stimulation. It acts on nicotinic and muscarinic receptors. Nicotinic receptors are ligand-gated ion channels that allow cation influx, while muscarinic receptors are G protein-coupled receptors that activate various intracellular effector pathways. After acting as a neurotransmitter, ACh is rapidly hydrolyzed by acetylcholinesterase to terminate its effects. Disorders of the cholinergic system can impact cognitive function, muscle contraction, and other processes.