Veins and arteries, while both part of the circulatory system, function quite differently from each other. “Poor circulation” is a nonspecific term that often refers to arterial blockages. Arteries bring oxygen-rich blood from the heart to the extremities and can be thought of like a tube or hose. Veins, unlike arteries, have one-way valves and channel oxygen-depleted blood back toward the heart. If the valves of the veins don’t function well, blood doesn’t flow efficiently. The veins become enlarged because they are congested with blood. These enlarged veins are commonly called spider veins or varicose veins. Spider veins are small red, blue or purple veins on the surface of the skin. Varicose veins are larger distended veins that are located somewhat deeper than spider veins. For symptoms, causes and treatment options – VNUS Closure procedure, click here.