The primary function of blood and blood circulation is to transport essential nutrients to and from the cells throughout the body. It constitutes the only means by which cells can receive materials necessary for their survival as well as have their waste products removed. Arteries carries the blood from the heart to the cells. This blood is enriched with oxygen as well as nutrients that are essential for cellular functions and well being.
Veins collect the deoxygenated blood and carry it back to the heart.
A second function of veins is that they act as reservoir vessels to help in the control of blood pressure. There are potentially two sources of arterial pain. First there is the acute episode of pain that occurs with an abrupt occlusion of the arterial flow to the tissues and cells of the body. This occlusion can lead to ischemia and eventually permanent tissue loss. The pain from this damage can be severe and if the cause of the arterial occlusion is not treated the damage from the disruption of blood flow to the area can be irreversible, i.e., myocardial infarction or arterial thrombosis.