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The Collaborative International Dictionary

acetylcholine \acetylcholine\ n.

  1. a neurotransmitter released by the transmitting dendron at autononmous synapses and at neuromuscular junctions. It is a quaternary amine with an obligatory negative counterion. The nominal formula for the hydroxide form is C7H17NO3. Structural formula (CH3)3N(+)CH2CH

  2. O.CO.CH

  3. OH(-).

    Note: Acetylcholine is the first recognized and best-studied of the neurotransmitters. At receptors it is recycled into choline by the action of acetylcholinesterase. Acetylcholinesterase inhibitors therefore function as nerve poisons. For biochemical studies it is prepared typically in the chloride or bromide forms.


n. (context neurotransmitter English) A neurotransmitter in humans and other animals. It is an ester of acetic acid and choline with chemical formula acetyloxygenmethylenemethylenenitrogen+(methyl)3.


n. a neurotransmitter that is a derivative of choline; released at the ends of nerve fibers in the somatic and parasympathetic nervous systems


Acetylcholine 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. Its name is derived from its chemical structure: it is an ester of acetic acid and choline. Parts in the body that use or are affected by acetylcholine are referred to as cholinergic. Substances that interfere with acetylcholine activity are called anticholinergics.

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. This property means that drugs that affect cholinergic systems can have very dangerous effects ranging from paralysis to convulsions. Acetylcholine is also used as a neurotransmitter in the autonomic nervous system, both as an internal transmitter for the sympathetic nervous system and as the final product released by the parasympathetic nervous system.

Inside the brain acetylcholine functions as a neuromodulator—a chemical that alters the way other brain structures process information rather than a chemical used to transmit information from point to point. The brain contains a number of cholinergic areas, each with distinct functions. They play an important role in arousal, attention, and motivation.

Partly because of its muscle-activating function, but also because of its functions in the autonomic nervous system and brain, a large number of important drugs exert their effects by altering cholinergic transmission. Numerous venoms and toxins produced by plants, animals, and bacteria, as well as chemical nerve agents such as Sarin, cause harm by inactivating or hyperactivating muscles via their influences on the neuromuscular junction. Drugs that act on muscarinic acetylcholine receptors, such as atropine, can be poisonous in large quantities, but in smaller doses they are commonly used to treat certain heart conditions and eye problems. Scopolamine, which acts mainly on muscarinic receptors in the brain, can cause delirium and amnesia. The addictive qualities of nicotine derive from its effects on nicotinic acetylcholine receptors in the brain.

Usage examples of "acetylcholine".

As a result, those nerve fibers which secrete acetylcholine are referred to as cholinergic nerves and those which secrete norepinephrine are adrenergic nerves.

The acetylcholine liberated at the axon endings of one nerve will affect the dendrites, or even the cell body itself, across the synapse and initiate a new nerve impulse there.

It is this acetylcholine which alters the working of the sodium pump so that depolarization takes place and the nerve impulse is initiated.

It is easy to visualize the acetylcholine as coating the membrane and altering its properties.

This is the picture some people draw of hormone action in general, and for this reason acetylcholine is sometimes considered an example of a neurohormone that is, a hormone acting on the nerves.

Instead, acetylcholine is secreted at the nerve-cell membrane and acts upon the spot.

The acetylcholine formed by the nerve cannot be allowed to remain in being for long, because there would be no repolarization while it is present.

Both formation and breakup of acetylcholine is brought about with exceeding rapidity, and the chemical changes keep up quite handily with the measured rates of depolarization and repolarization taking place along the course of a nerve fiber.

All nerve cells contain the enzymes that form acetylcholine and break it down.

The secretion of acetylcholine alters the properties of the muscle cell membrane, brings about the influx of sodium ion, and, in short, initiates a wave of depolarization just like that which takes place in a nerve cell.

Any substance that will inhibit the action of cholinesterase and put an end to the cycle of acetylcholine buildup and breakdown thus will not only put an end to the nerve impulse but will also put an end to the stimulation and contraction of muscles.

Here the most likely fault is that the acetylcholine formation at the neuromuscular junction is insufficient, or perhaps that it is formed in normal amounts but is too quickly broken down by cholinesterase.

The therapeutic use of a cholinesterase-inhibitor conserves the acetylcholine and can, at least temporarily, improve muscle action.

Esterases in the body break the drug down rapidly into acetylcholine, so it is also likely to be undetectable, unless the target happens to croak right outside a primo medical center with a very sharp pathologist who is looking for something out of the ordinary.

Esterases in the body break the chemical down into acetylcholine fairly rapidly, so it is very likely to be undetectable, even by someone up at Columbia-Presbyterian.