The heart pumps the blood through a system of blood vessels known as the circulation system. Blood vessels are hollow, flexible tubes that transport the blood throughout the body. The circulation system contains the arteries that carry the oxygen-rich blood from the heart to other body parts. It also contains the veins, which carry the deoxygenated blood back to the heart.
The veins are hollow tubes that have flaps inside, known as the valves. Different from arteries, the veins have few muscle cells on their wall. Additionally, the veins do not benefit from the heart pumping pressure to help circulate the blood. Our veins depend on muscle movement to ensure that the blood flows back to the heart. As the muscles contract, the valve opens to allow the blood to flow through the veins. When the muscles relax, the valve closes, ensuring that blood flows in one direction.
The valves in the veins are fragile and lose their efficacy as we grow old. Damaged or missing valves force the blood to stagnate in the veins. When this happens, our immune system activates, triggering the inflammatory process, which leads to various symptoms.