what do veins have that arteries lack quizlet
Veins have much thinner walls, because the blood they carry is under low pressure. VEINS have valves that aid the return of blood to the heart and prevent blood from going backwards. ARTERIES do not have valves, except for the semi-lunar valves of the pulmonary artery and the aorta. ARTERIES have relatively narrow lumens, VEINS have relatively wide lumens.