health

The circulatory system has two main types of vessels for carrying blood to
and from all of the body’s cells, tissues, and organs. Arteries carry oxygenrich
blood from the heart to the organs, and veins return oxygen-poor
blood to the heart. Both arteries and veins are vessels or tubes through
which blood flows, but they are dissimilar in many ways. Arteries have
much thicker walls than veins of comparable size. Both arteries and veins
have rings of smooth muscle surrounding them, but arteries have thicker
rings. Arteries have many more elastic fibers than veins and have the property
of elasticity. Veins are relatively inelastic. In addition, blood pressure
in the veins is much lower than it is in the arteries. Veins do have valves,
which help to keep blood from pooling in the veins. When these valves
start to break down, as often happens in older or inactive people, the
veins sometimes dilate* or collapse and become varix, varices, varicose*.
The result is varicose veins. Although varicose veins can be painful, most
varicose veins are relatively benign*.