What role do neurotransmitters play in the nervous system?

Neurotransmitters play a critical role in the nervous system by transmitting signals across synapses, which are the junctions between neurons. When an electrical impulse, or action potential, travels down a neuron and reaches the end of the axon, neurotransmitters are released into the synaptic cleft. These chemicals then bind to receptor sites on the postsynaptic neuron, allowing the signal to continue its journey. This process is essential for communication within the brain and throughout the entire nervous system, facilitating everything from reflexes to complex cognitive tasks.

The other options do not accurately describe the role of neurotransmitters. While some parts of the nervous system do require structural support, that is the function of glial cells, not neurotransmitters. The regulation of hormonal activity is largely the function of hormones themselves, not neurotransmitters. Additionally, neurotransmitters do not act as energy sources; neurons primarily use glucose for energy to function effectively.