Which term describes the chemical messengers that transmit signals across the synaptic gap between neurons?

The term that describes the chemical messengers that transmit signals across the synaptic gap between neurons is neurotransmitter. Neurotransmitters are released from the presynaptic neuron and travel across the synaptic cleft to bind to receptors on the postsynaptic neuron. This binding process is crucial for the transmission of signals within the nervous system, allowing for communication between neurons and playing a key role in various functions including mood, cognition, and muscle contraction.

Other options represent different types of biological messengers or substances that serve distinct functions. Hormones, for instance, are chemicals released into the bloodstream and affect distant organs and tissues rather than acting locally at synapses. Enzymes are biological catalysts that speed up chemical reactions but do not function as signaling molecules. Neuromodulators, while they do influence neuronal activity, typically act over longer distances and through different mechanisms than neurotransmitters. Therefore, the precision and localized action of neurotransmitters are essential characteristics that define their role in synaptic transmission.