Baroreceptors respond to changes in which parameter?

• A. Temperature
• B. Blood Viscosity
• C. Arterial Wall Distension
• D. Blood Pressure

Answer: (D)

Baroreceptors are stretch-sensitive nerve endings located in the carotid sinus and aortic arch that monitor how much the arterial walls are distended. The amount of wall stretch reflects the blood pressure inside the vessels, so these receptors respond to changes in blood pressure. When pressure rises, increased distension elevates their firing rate, signaling the brain to raise parasympathetic activity and reduce sympathetic activity to lower pressure. When pressure falls, reduced distension lowers their firing, prompting actions to raise blood pressure. So the parameter they monitor and respond to is blood pressure, with arterial wall distension serving as the mechanical signal that indicates that pressure. Temperature and viscosity aren’t what baroreceptors track.