different kinds of veins
Vein Types. Veins can be categorized into four main types: pulmonary, systemic, superficial, and deep veins. Pulmonary veins carry oxygenated blood from the lungs to the left atrium of the heart. Systemic veins return oxygen-depleted blood from the rest of the body to the right atrium of the heart. Superficial veins are located close to the surface of the skin and are not located near a corresponding artery.