AAMC FL Practice Exam

What is the role of chemical messengers in the CNS?

1. They store memories

2. They bind to receptors on the postsynaptic membrane

3. They create physical sensations

4. They function only during sleep

The correct answer is: They bind to receptors on the postsynaptic membrane

Chemical messengers, often referred to as neurotransmitters, play a crucial role in the central nervous system (CNS) by transmitting signals between neurons. When a neurotransmitter is released from a presynaptic neuron, it travels across the synaptic cleft and binds to specific receptors located on the postsynaptic membrane. This binding can initiate a response in the postsynaptic neuron, leading to either excitation or inhibition, depending on the type of neurotransmitter and receptor involved. This mechanism is fundamental to communication within the CNS, influencing processes such as mood, cognition, movement, and various autonomic functions. By binding to receptors, these chemical messengers are integral to how information is processed and relayed through neural circuits. Other options, while related to functions in the CNS, do not accurately describe the primary role of chemical messengers. For example, the storage of memories is a complex process involving various structural and functional changes in neural connections, while physical sensations arise from sensory processing and perception, not directly from the messengers themselves. Additionally, neurotransmitters are not limited to functioning only during sleep; they are active continuously, influencing various states of consciousness and activity throughout the day.