Baroreceptors in the carotid sinus and aortic arch are sensitive to changes in what parameter?

• A. Arterial pressure
• B. Venous pressure
• C. Blood oxygen level
• D. Blood pH

Answer: (A)

Baroreceptors in these locations sense how stretched the arterial wall is, which reflects arterial pressure. When pressure rises, increased wall stretch raises their firing rate, sending signals to the brainstem that trigger a response to lower pressure—slowing the heart, reducing contractility, and dilating vessels. When pressure falls, reduced stretch lowers firing, prompting a response that raises pressure by increasing heart rate, contractility, and vasoconstriction. They aren’t measuring venous pressure, oxygen levels, or pH; their primary role is monitoring arterial pressure to help maintain stable blood pressure.