AAMC FL Practice Exam

What are neurotransmitters primarily considered?

1. Hormones that regulate mood

2. Chemical messengers within the CNS

3. Electrochemical signals used for muscle contraction

4. Proteins that form neural connections

The correct answer is: Chemical messengers within the CNS

Neurotransmitters are primarily considered chemical messengers within the central nervous system (CNS). They play a crucial role in transmitting signals between neurons and also between neurons and other target cells, such as muscle cells or gland cells. Neurotransmitters are released from the presynaptic neuron into the synaptic cleft and bind to specific receptors on the postsynaptic neuron, facilitating the communication process that underpins neural functions, including mood regulation, reflexes, and many other vital processes. In this context, neurotransmitters do not function as hormones, which are typically secreted into the bloodstream and have broader effects on various tissues throughout the body. They are also not electrochemical signals used directly for muscle contraction; rather, neurotransmitters initiate the process of muscle contraction by stimulating muscle cells. Lastly, while neurotransmitters are involved in the formation of neural connections, they are not proteins; they are primarily small molecules synthesized and released by nerve cells. Thus, identifying them as chemical messengers within the CNS captures their essential role in neural communication.