Blood vessel prevent backflow as a result of a decrease in blood pressure as the blood passes through the circulatory system. There are various kinds of blood vessels: They are roughly grouped as "arterial" and "venous", determined by whether the blood in it is flowing "away from" (arterial) or "toward" (venous) the heart. The term "arterial blood" is nevertheless used to indicate blood high in oxygen, although the pulmonary artery carries "venous blood" and blood flowing in the pulmonary vein is rich in oxygen. This is because they are carrying the blood to and from the lungs, respectively, to be oxygenated. Blood
Superficial vein Superficial vein Superficial vein is a vein that is close to the surface of the body. This differs from deep veins that are far from the surface. Superficial veins are not paired with an artery, unlike the deep veins, which typically have an artery with the same name close by. Superficial veins are important physiologically for cooling of the body. When the body is too hot the body shunts blood from the deep veins to the superficial veins, to facilitate heat transfer to the surroundings. Superficial veins can be seen under the skin. Those below the level of the heart