Neural Regulation of Blood Vessels
Most blood vessels are innervated by sympathetic nerve fibers. The vasomotor center within the medulla oblongata plays a major role in regulating the frequency of action potentials in nerve fibers that innervate blood vessels and thus the diameter of blood vessels. Baroreceptors are located in the ascending aorta, aortic arch, and carotid sinus. They detect changes in blood pressure. Chemoreceptors located in the carotid bodies and the aortic bodies detect changes in blood pH, O₂ levels, and CO₂ levels.