Which vessels carry blood away from the heart?

• A. Veins
• B. Capillaries
• C. Lymphatics
• D. Arteries

Answer: (D)

Blood leaves the heart through arteries, propelled by the pumping action of the ventricles. Arteries are built with thick, muscular walls to withstand the high pressure of this outflow as blood travels to the lungs and to the rest of the body. Veins, on the other hand, carry blood back toward the heart and often have valves to prevent backflow. Capillaries are the tiny, thin-walled vessels where exchange of oxygen, nutrients, and wastes occurs between blood and tissues, linking arteries to veins. Lymphatics carry lymph, not blood, and are part of the immune and fluid balance system. Remember the rule that direction matters: arteries carry blood away from the heart, even though the pulmonary artery carries blood to the lungs with low oxygen content.