ABSTRACT
This chapter reviews alterations in the function of different components of the baroreflex in hypertension. Arterial baroreceptors are distortion receptors. Major vascular sites where these receptors are located are the carotid sinus and the aortic arch. Ultrastructural studies on baroreceptors indicate that unmyelinated axons form terminals and intercalated expansions of different sizes at the border of adventitia and media. In most species of animals, the baroreceptor afferents from the carotid sinus and chemoreceptor afferents from the carotid body travel in the carotid sinus nerve, which joins the glossopharyngeal nerve. The baroreceptor afferents from the aortic arch travel in the aortic depressor nerve, which is independent of the cervical vagus in the rat and the rabbit. Medullated nonmedullated fibers are present in the nerves carrying the baroreceptor afferents. Degenerative changes in baroreceptors have also been reported in patients with essential hypertension. These reports indicate that degenerative changes in the baroreceptors may have some role to play in certain forms of hypertension.
