Which of the following best describes the function of neurotransmitters?

Neurotransmitters are chemical messengers that play a crucial role in communication between neurons within the nervous system. The primary function of neurotransmitters is to facilitate the transmission of signals across synapses— the junctions between neurons. When a neuron is activated, it releases neurotransmitters into the synaptic cleft, where they bind to specific receptors on the post-synaptic neuron. This binding typically leads to immediate physiological responses, such as the generation of an action potential in the post-synaptic neuron, thus facilitating rapid communication within the brain and body.

This local action is key to the functioning of the nervous system, allowing for quick responses to stimuli. This is in stark contrast to hormones, which travel through the bloodstream and affect distant targets to regulate longer-term processes. Hence, the description of neurotransmitters as acting locally across synapses for immediate response accurately portrays their essential role in neuronal communication.