Final answer:
Nitric oxide is an example of a neuromodulator, which adjusts the sensitivity of neurons to neurotransmitters or alters neurotransmitter release. Acetylcholine is a direct neurotransmitter, not a modulator.
Step-by-step explanation:
Good Examples of a Neuromodulator
Among the choices given, nitric oxide is a good example of a neuromodulator. While acetylcholine is indeed a neurotransmitter, it is more directly involved in synaptic transmission rather than modulating the effectiveness of other neurotransmitters. Nitric oxide, on the other hand, plays a more diffuse role in the nervous system, often affecting the activity of other neurotransmitters and thus functioning as a neuromodulator. Proteins and carbohydrates do not generally serve as neuromodulators but are essential for various biological processes including structure, enzymes, energy storage, and cell recognition.
Neuromodulators modify neural signaling by adjusting the sensitivity of neurons to specific neurotransmitters or by changing the rate of neurotransmitter release. Nitric oxide is known to be involved in the formation of long-term potentiation (LTP), a process related to memory and learning, and it can diffuse freely across cell membranes impacting nearby neurons.