What neural reflex helps regulate blood pressure on a short-term basis?

• A. Baroreceptors regulate oxygen delivery to tissues.
• B. The reflex is driven by chemoreceptors in the carotid bodies.
• C. The baroreceptor reflex, mediated by the carotid sinus and aortic arch baroreceptors.
• D. It regulates renal perfusion directly.

Answer: (C)

Short-term blood pressure control is achieved by the baroreceptor reflex, which uses baroreceptors in the carotid sinus and aortic arch to sense how stretched the arterial walls are. When pressure goes up, these receptors fire more, signaling the brainstem to boost parasympathetic output and reduce sympathetic activity. The result is a slower heart rate and vasodilation, bringing blood pressure back toward normal quickly. When pressure drops, firing falls, and sympathetic tone increases while parasympathetic activity decreases, raising heart rate and causing vasoconstriction to restore pressure. This rapid, beat-to-beat adjustment is not about oxygen delivery or renal perfusion, which operate on longer time scales or through different sensors (chemoreceptors respond to blood gases and pH, and renal mechanisms control BP over the long term).