What is the role of neurotransmitters?

Neurotransmitters play a crucial role in the nervous system by transmitting signals across a synapse between neurons. When an electrical signal called an action potential reaches the end of a neuron, neurotransmitters are released from vesicles into the synaptic cleft, which is the small gap between neurons. These chemicals then bind to specific receptors on the surface of the adjacent neuron, allowing for communication and the propagation of the signal throughout the nervous system. This process is fundamental for various functions, including muscle contractions, reflexes, and higher cognitive processes such as learning and memory.

The other options, while related to physiological functions, do not specifically describe the primary role of neurotransmitters in signal transmission. Maintaining homeostasis and regulating blood flow are complex processes involving multiple mechanisms and systems, and providing structural support pertains to supportive cells like glial cells, rather than the function of neurotransmitters themselves.