National Certified Addiction Counselor, Level 2 (NCAC II) Practice Exam Exam

Which neurotransmitter is categorized as excitatory and indicates to a neuron to send a message?

1. Dopamine

2. Norepinephrine

3. Acetylcholine

4. Serotonin

The correct answer is: Acetylcholine

Acetylcholine is recognized as an excitatory neurotransmitter that plays a crucial role in signaling between neurons, specifically at the neuromuscular junction and within the central nervous system. When acetylcholine binds to its receptors on the postsynaptic neuron, it typically triggers an excitatory response, leading to depolarization of the neuron. This process increases the likelihood that the neuron will fire an action potential, effectively sending a message to other neurons or muscles. Acetylcholine's excitatory action is particularly significant in motor functions and various cognitive processes, including learning and memory. Therefore, its categorization as an excitatory neurotransmitter is well-supported by both its mechanism of action and its physiological roles. The other neurotransmitters listed, while having important functions, may also have mixed effects depending on the context or type of receptors involved. For instance, dopamine and norepinephrine can be excitatory or inhibitory based on their receptor types, and serotonin primarily plays a role in mood regulation rather than direct excitatory signaling in the context of neuronal messaging.