How are arteries different from veins in the human circulatory system?

Arteries and veins are distinct components of the circulatory system with specialized structures and functions:

• Direction of Flow: Arteries typically carry oxygenated blood away from the heart to the body, while veins return oxygen-depleted blood toward the heart. The primary exceptions are the pulmonary vessels, where the roles are reversed.12
• Pressure and Walls: Arteries must withstand intense pressure from the heart’s pumping action, resulting in thicker, more muscular, and elastic walls. Veins operate under substantially lower pressure, featuring thinner, more compliant walls that allow them to act as blood reservoirs.123
• Valves: To assist blood flow against gravity—particularly in the limbs—many veins contain valves that prevent the backflow and pooling of blood. Arteries do not require these valves because the force of the heartbeat maintains forward momentum.12
• Anatomy: Veins are more numerous than arteries and generally have larger internal diameters (lumens). While both possess three-layered walls, the elastic membrane found in the inner layer of an artery is absent in veins.2