Vasodilation is where blood vessels in the body become wider following the relaxation of the smooth muscle in the vessel wall. This will reduce blood pressure - since there is more room for the blood. Vasodilation also occurs in superficial blood vessels of warm-blooded animals when their ambient environment is hot; this process diverts the flow of heated blood to the skin of the animal, where heat can be more easily released into the atmosphere. The opposite physiological process is vasoconstriction. Vasomotor refers to the muscles and nerves controlling the process of vasodilation. A vasodilator is a substance that causes vasodilation. Several vasodilators are used as drugs which may, for example, allow blood to flow more easily around a clot. Flushing may be a physiological response to vasodilators.