are the veins going to or from the heart
The pulmonary veins carry relatively oxygenated blood from the lungs to the heart. The superior and inferior venae cavae carry relatively deoxygenated blood from the upper and lower systemic circulations, respectively. The portal venous system is a series of veins or venules that directly connect two capillary beds.n contrast to veins, arteries carry blood away from the heart. Veins are less muscular than arteries and are often closer to the skin. There are valves in most veins to prevent backflow.