Which structures contain baroreceptors that help regulate arterial pressure?

Which structures contain baroreceptors that help regulate arterial pressure?

• A. Aortic arch and carotid sinus
• B. Right atrium and ventricle
• C. Pulmonary artery and hilum
• D. Capillary beds in the legs

Answer: (A)

Baroreceptors detect arterial pressure by sensing stretch in the vessel walls. They are located mainly in the carotid sinus and the aortic arch. When blood pressure rises, increased stretch speeds up their firing, sending signals to the brainstem to decrease sympathetic activity and increase parasympathetic activity, which lowers heart rate, reduces contractility, and dilates vessels to bring pressure down. If blood pressure falls, firing quiets, triggering more sympathetic output and less parasympathetic input, which raises heart rate, contractility, and vascular tone to raise pressure. The other sites listed don’t serve as primary sensors for systemic arterial pressure: the right atrium and ventricle monitor volume-related signals; the pulmonary artery and hilum relate to the pulmonary circulation rather than systemic arterial pressure; and capillary beds do not contain baroreceptors.

Baroreceptors detect arterial pressure by sensing stretch in the vessel walls. They are located mainly in the carotid sinus and the aortic arch. When blood pressure rises, increased stretch speeds up their firing, sending signals to the brainstem to decrease sympathetic activity and increase parasympathetic activity, which lowers heart rate, reduces contractility, and dilates vessels to bring pressure down. If blood pressure falls, firing quiets, triggering more sympathetic output and less parasympathetic input, which raises heart rate, contractility, and vascular tone to raise pressure. The other sites listed don’t serve as primary sensors for systemic arterial pressure: the right atrium and ventricle monitor volume-related signals; the pulmonary artery and hilum relate to the pulmonary circulation rather than systemic arterial pressure; and capillary beds do not contain baroreceptors.