Acetylcholine is a neurotransmitter in both the central nervous system and peripheral nervous system of vertebrates. It is a white crystalline derivative of choline, C7H17NO3, that is released at the end of axons and is involved in the transmission of nerve impulses in the body. In the cerebral cortex, it is important in memory and learning processes.
Acetylcholine carries nerve impulses across the synaptic gap, from one neuron to another. It functions as a chemical messager whose message is read via receptors in the neurons and muscle tissues. It is active at many nerve synapses and at the motor end plate of vertebrate voluntary muscles.
In the peripheral nervous system, acetylcholine activates muscles, and is a major neurotransmitter in the autonomic nervous system. In the central nervous system, acetylcholine and the associated neurons form a neurotransmitter system, the cholinergic system, which tends to cause excitatory actions.