Acetylcholine is a chemical produced at many nerve endings in the body, and receptors which bind acetylcholine are called cholinergic receptors. Cholinergic nerves regulate heart rate, blood pressure, digestive processes, bowel and bladder function, memory, alertness, eye pressure and muscle function. Drugs that block these nerves (see anticholinergic) can alter these bodily functions.
Those parts of the nervous system, both peripheral and in the brain, using acetylcholine as a neurotransmitter. Acetylcholine released at the synapse (junction) between a motor nerve and a muscle fiber causes the muscle fiber to contract. Acerylcholine is am important brain neurotransmitter, too, being involved in memory, long-term planning, control of mental focus, sexual activity, and other functions. It is made in the body from choline in reactions requiring the availability of adequate vitamin B-5 (as part of hte acetyl co-enzyme A).