Canadian Health Information Management Association Practice Exam

Which of the following is classified as a small molecule neurotransmitter?

1. Acetylcholine.

2. Biogenic amines.

3. Endorphins.

4. Purines.

The correct answer is: Acetylcholine.

Acetylcholine is classified as a small molecule neurotransmitter because it is synthesized in nerve terminals and is involved in transmitting signals across synapses. It plays a crucial role in both the central and peripheral nervous systems, affecting muscle activation, memory, and attentiveness. Small molecule neurotransmitters are generally characterized by their relatively low molecular weight and their distinct synthesis pathways that allow them to be rapidly produced and released in response to neuronal signaling. In contrast, other classifications exist for the remaining options. Biogenic amines, while they are neurotransmitters, encompass a broader category that includes substances like dopamine, norepinephrine, and serotonin, which are derived from amino acids. Endorphins are classified as neuropeptides, which are larger molecules composed of chains of amino acids and often involved in pain regulation and stress response. Purines, such as adenosine, act as signaling molecules but differ in structure and function from classical small molecule neurotransmitters. The specific structural and functional characteristics of acetylcholine distinctly classify it within the small molecule neurotransmitters category.