1. Blood Vessels Arteries, veins, and capillaries

2. Arteries Take blood away from the heart Have thick walls Usually carry oxygen-rich blood – Exception: The pulmonary artery carries oxygen- poor blood from the heart to the lungs

3. Veins Take blood to the heart Have thin walls Usually carry oxygen-poor blood – Exception: The pulmonary vein carries oxygen- rich blood to the heart from the lungs

4. Capillaries Very small Have very thin walls for oxygen and nutrients in exchange for carbon dioxide and waste Artery Capillaries Vein Blood flow

5. Blood vessels and organs