Acetylcholine

Acetylcholine (ACh, pron. ah-Seh-til-KO-leen) is an organic molecule that acts as a neurotransmitter in many organisms, includinghumans. It is an ester of acetic acid and choline, with chemical formula CH
3COO(CH
2)₂N+(CH
3)₃ and systematic name 2-acetoxy-N,N,N-trimethylethanaminium.

Acetylcholine is one of many neurotransmitters in the autonomic nervous system (ANS). It acts on both the peripheral nervous system (PNS) and central nervous system (CNS) and is the only neurotransmitter used in the motor division of the somatic nervous system. Acetylcholine is also the principal neurotransmitter in all autonomic ganglia.^{[citation needed]}

In cardiac tissue acetylcholine neurotransmission has an inhibitory effect, which lowers heart rate. However, acetylcholine also behaves as an excitatory neurotransmitter at neuromuscular junctions in skeletal muscle.