Baroreceptors

(baroceptors, mechanoreceptors, and pressoreceptors), sensory nerve terminals in blood vessels that perceive changes in blood pressure and reflexly regulate its level. Baroreceptors become stimulated when the walls of the vessels distend. They are found in all vessels but are concentrated mainly in reflexogenic zones (such as cardiac, aortic, carotid sinus, and pulmonary). When blood pressure rises, baroreceptors send impulses to the central nervous system that decrease the tonus of the vascular center and excite the central formations of the parasympathetic division of the autonomic nervous system, and result in a lowering of the pressure. After a frequent and prolonged rise in blood pressure, the baroreceptors adapt to it and thereby may be one of the causes of hypertension.