Neurohormone

Part of speech: noun

Definitions

1. A chemical substance released by nerve cells into the blood, where it carries signals to distant organs and tissues
2. A hormone produced and discharged by neurons that acts on target cells throughout the body to regulate physiological processes
3. A signaling molecule that nerve cells secrete into circulation so that it can influence glands, muscles, or other organs far away

Etymology: Neurohormone is a plain modern compound: "neuro-", from Greek "neuron" meaning "nerve", joined to "hormone", a word borrowed from Greek "hormōn" meaning "setting in motion" or "stimulating". The result names a chemical that nerve cells release into the blood, so it works as a hormone while being produced by neurons rather than by a gland. The combination reflects a shift in how scientists thought about the body's messengers. Hormones were first understood as substances made by glands and carried through the bloodstream to distant organs. Once it became clear that some nerve cells also secrete chemicals into the blood, a term was needed that linked the two systems, and "neurohormone" fills that role by joining the nervous and endocrine vocabularies in a single word. The two halves therefore carry the history of their fields: "neuro-" points to the nerve cell as the source, and "hormone" points to the chemical's job of stimulating a response at a distance. Few other words in the family were built to describe a hybrid of this kind, which is why the compound reads so transparently.