What role do neurotransmitters play in the nervous system?

Neurotransmitters are chemical messengers that play a crucial role in transmitting signals across synaptic gaps, which are the small spaces between neurons. When an electrical impulse, or action potential, reaches the end of a neuron (the presynaptic terminal), neurotransmitters are released into the synaptic gap. These chemicals then bind to specific receptors on the neighboring neuron's surface (the postsynaptic terminal), allowing for the transmission of the signal. This process is essential for communication between neurons and facilitates various functions in the nervous system, including muscle movement, sensory perception, and cognitive processes.

The other options describe distinct processes in neuronal function but do not accurately depict the primary role of neurotransmitters. For instance, while some neurotransmitters can inhibit muscle contractions, this is just one specific function of certain neurotransmitters in specific contexts. Similarly, action potentials are not triggered by neurotransmitters themselves within the axon; rather, they are the result of ion movement across the neuron's membrane due to changes initiated by the binding of neurotransmitters at the synapse. Lastly, the development of insulation in neurons, which is primarily attributable to myelin sheaths formed by glial cells, does not involve neurotransmitters, but rather focuses