Baroreflex

The baroreflex is a rapid feedback system in which stretch-sensitive receptors detect changes in arterial pressure and trigger adjustments in heart activity and blood-vessel tone.

Baroreceptor: A sensory receptor that detects stretch in blood-vessel walls and converts it into nerve signals. Carotid and aortic baroreceptors supply the pressure signals that initiate the reflex.
Arterial blood pressure: The force exerted by circulating blood on the walls of arteries. It is the regulated variable whose rises and falls alter baroreceptor firing.
Orthostatic hypotension: A fall in blood pressure on standing that can cause dizziness or fainting. Impaired or insufficient compensation by the baroreflex can contribute to this pressure drop.
Renin–angiotensin system: A hormonal system that regulates blood pressure and fluid balance through renin, angiotensin, and aldosterone. It supports pressure regulation over minutes to days, unlike the baroreflex's rapid neural action.
Carotid sinus: A dilated region at the base of the internal carotid artery containing pressure-sensitive nerve endings. Its stretch receptors report arterial pressure through the glossopharyngeal nerve.
Heart rate: The number of heartbeats per unit of time, usually measured in beats per minute. The reflex changes heart rate to alter cardiac output and pressure.
Syncope: A brief loss of consciousness caused by reduced blood flow to the brain. Failure to maintain pressure, or an excessive reflex response, can lead to fainting.
Atrial natriuretic peptide: A hormone released mainly by stretched heart atria that promotes sodium and water excretion. It responds to cardiac stretch through hormonal and renal effects rather than rapid arterial nerve feedback.
Aortic arch: The curved section of the aorta that carries blood from the heart toward the body. Stretch receptors in its wall send pressure information through the vagus nerve.
Cardiac output: The volume of blood pumped by the heart per unit of time. Changing heart rate and contractility lets the reflex influence arterial pressure through output.

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