The short-term regulation of blood pressure is primarily mediated by which mechanism?

The short-term regulation of blood pressure is primarily mediated by which mechanism?

• A. Renin-Angiotensin System
• B. Atrial Natriuretic Peptide
• C. Aldosterone
• D. Baroreceptor Reflex

Answer: (D)

Short-term arterial blood pressure is governed by the baroreceptor reflex, a rapid neural feedback loop. Stretch sensors in the carotid sinus and aortic arch detect changes in arterial pressure and send signals to the brainstem. The brain then adjusts autonomic output to the heart and blood vessels: if pressure rises, sympathetic activity decreases and parasympathetic activity increases, lowering heart rate, contractility, and vascular resistance; if pressure falls, the opposite occurs to raise blood pressure. This swift reflex operates within seconds to stabilize mean arterial pressure. Hormonal systems like the renin-angiotensin-aldosterone axis, atrial natriuretic peptide, and aldosterone regulate blood pressure more slowly by affecting blood volume and vascular tone over minutes to hours, so they are not the primary short-term regulators.

Short-term arterial blood pressure is governed by the baroreceptor reflex, a rapid neural feedback loop. Stretch sensors in the carotid sinus and aortic arch detect changes in arterial pressure and send signals to the brainstem. The brain then adjusts autonomic output to the heart and blood vessels: if pressure rises, sympathetic activity decreases and parasympathetic activity increases, lowering heart rate, contractility, and vascular resistance; if pressure falls, the opposite occurs to raise blood pressure. This swift reflex operates within seconds to stabilize mean arterial pressure. Hormonal systems like the renin-angiotensin-aldosterone axis, atrial natriuretic peptide, and aldosterone regulate blood pressure more slowly by affecting blood volume and vascular tone over minutes to hours, so they are not the primary short-term regulators.