What does the abbreviation ACh stand for?

• A. Acetylcholine
• B. ACh
• C. Acetylcholesterin
• D. Choline

Answer: (A)

ACh stands for acetylcholine, a key neurotransmitter at cholinergic synapses. It is produced from choline and acetyl-CoA, stored in vesicles, and released in response to nerve impulses. Once released, it activates acetylcholine receptors—nicotinic receptors at the neuromuscular junction and muscarinic receptors in various organs—producing muscle contraction and parasympathetic effects. Its action is quickly terminated by acetylcholinesterase, which breaks it down into choline and acetate. This makes acetylcholine the correct expansion of the abbreviation. The other options are not correct: one is simply the abbreviation itself, another is a misspelling, and the last is only the precursor molecule, not the neurotransmitter.