Chromaffin System

The network of catecholamine-producing chromaffin cells, located chiefly in the adrenal medulla and in extra-adrenal paraganglia. It links neural signals to rapid hormonal release of epinephrine and norepinephrine.

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Sympathetic nervous system: The division of the autonomic nervous system that mobilizes the body during stress and activity. Preganglionic sympathetic neurons directly stimulate adrenal chromaffin cells.
Chromaffin cell: A catecholamine-secreting neuroendocrine cell found chiefly in the adrenal medulla and paraganglia. These cells are the network’s defining cellular units.
Fight-or-flight response: A coordinated physiological response that prepares the body for acute challenge through sympathetic and hormonal activity. Chromaffin catecholamines amplify this response throughout the body.
Sympathoadrenal lineage: A developmental lineage of neural crest-derived cells that gives rise to sympathetic neurons and adrenal chromaffin cells. It is the shared developmental route into the system’s principal cell types.
Splanchnic nerves: Visceral nerves that carry preganglionic sympathetic fibers to abdominal and pelvic organs. Their preganglionic fibers deliver the neural command to the adrenal medulla.
Adrenal medulla: The inner region of the adrenal gland, containing chromaffin cells that release catecholamines into blood. It is the largest and best-known concentration of chromaffin tissue.
Pheochromocytoma: A usually adrenal tumor of chromaffin cells that can secrete excess catecholamines. This tumor arises from the system’s adrenal component.
Adrenal gland development: The embryonic formation of the adrenal cortex and medulla from distinct developmental tissues. The medulla forms as chromaffin precursors associate with the developing adrenal gland.
Acetylcholine: A neurotransmitter that activates nicotinic and muscarinic receptors in the nervous system. It is released onto chromaffin cells and initiates their secretion.
Paraganglion: A cluster of neuroendocrine cells associated with autonomic nerves and blood vessels. Extra-adrenal chromaffin cells occur in paraganglia, especially during development.