barorécepteur

Barorécepteur (baroreceptor) refers to stretch-sensitive nerve endings that detect changes in arterial blood pressure. The most important baroreceptors are located in the carotid sinus and the aortic arch. They respond to arterial wall stretch during pulsatile flow: when blood pressure rises, the firing rate of afferent fibers increases; when pressure falls, firing rate decreases. Afferent signals travel from the carotid sinus via the glossopharyngeal nerve (cranial nerve IX) and from the aortic arch via the vagus nerve (cranial nerve X) to the nucleus tractus solitarius in the medulla oblongata.

Central processing integrates baroreceptor input with other cardiovascular signals and modulates autonomic output to the heart and blood vessels. The baroreflex acts as a rapid negative feedback mechanism that stabilizes short-term blood pressure. Elevated pressure leads to reduced sympathetic activity and increased parasympathetic activity, causing a slower heart rate, reduced contractility, and vasodilation. Reduced pressure invokes the opposite response: increased sympathetic tone and decreased parasympathetic influence, raising heart rate, contractility, and vascular tone.

The baroreflex is fast but adaptable; with sustained blood pressure changes, the set-point can reset over time, a phenomenon observed in chronic hypertension where the reflex maintains sensitivity around a higher baseline. Clinically, maneuvers such as carotid sinus massage can transiently engage the baroreflex to slow the heart in certain tachyarrhythmias, while impaired baroreceptor function or baroreflex sensitivity can contribute to labile blood pressure or orthostatic hypotension.