Final answer:
Blood pressure is controlled by four anatomical sites: baroreceptors, chemoreceptors, smooth muscle in blood vessel walls, and adrenergic receptors.
Step-by-step explanation:
Blood pressure is controlled by four anatomical sites: baroreceptors located in the aorta, carotid arteries, venae cavae, and atria; chemoreceptors found both in the central nervous system and in proximity to baroreceptors; smooth muscle in the walls of blood vessels; and adrenergic receptors that respond to the release of norepinephrine from sympathetic fibers by constricting blood vessels and increasing blood pressure.