What are chemicals that relay, amplify, and modulate signals between a neuron and another cell?

Neurotransmitters play a critical role in the communication between neurons and other cells in the nervous system. They are specialized chemicals that are released from the end of a neuron at the synapse (the junction between two neurons) and bind to specific receptors on the surface of the adjacent cell. This binding triggers a response in the target cell, which can either be excitatory or inhibitory, effectively relaying, amplifying, and modulating the original signal.

Neurotransmitters are essential for a variety of neural functions, including muscle contractions, mood regulation, and the processing of information in the brain. Their action is swift, allowing for rapid communication within the nervous system, which is crucial for timely responses to stimuli.

Other types of chemicals, such as hormones, enzymes, and receptors, serve different functions in the body. Hormones typically circulate through the bloodstream and have broader effects over longer periods, while enzymes catalyze biochemical reactions. Receptors are proteins that bind to signaling molecules but do not themselves relay signals; rather, they are the targets for neurotransmitters and other signaling substances.