What Are Veins and Arteries?
The body has two systems for carrying blood to and from all its cells, tissues, and organs. Arteries carry blood from the heart to the organs, and veins return blood back to the heart. Although veins and arteries are similar in structure, veins usually carry blood with less oxygen than arteries do, and vein walls are thinner and weaker than arterial walls. When veins become injured or empty, they sometimes dilate* or collapse and become varicose*.
