Which of the following correctly describes how the baroreceptor reflexes would respond to a fall in blood pressure? The cardioinhibitory center would be stimulated. The vasomotor center would increase sympathetic output to arterial smooth muscle to increase TPR. Contractility would decrease and heart rate would increase. Baroreceptors would be stimulated and send increased impulses to the cardiovascular control center in the medulla. The cardioacceleratory center would increase parasympathetic output to the heart.

The correct answer is: The vasomotor center would increase sympathetic output to arterial smooth muscle to increase TPR.

Baroreceptors are mechanoreceptors (sensors or modified nerve endings) found in the blood vessels and their function is to detect the change in blood pressure and participate in the regulation of it (so that proper blood pressure can be maintained). The action of baroreceptors or baroreflex works as a negative feedback loop: when the blood pressure is decreased, baroreflex activation also decreases (baroreceptors are active even at normal blood pressures) and causes heart rate to increase.

Decreased blood pressure leads to lower baroreceptor "firing" which then results in an increase in sympathetic stimulation of the heart and sympathetic stimulation of the peripheral vessels, resulting in vasoconstriction. As a result blood pressure increase.