What causes varicose veins, gravity?

Not gravity: Incompetent valves in the venous system of the leg, especially the saphenous vein, lead to varicose veins. Of course, they would not occur except that gravity then pulls the blood back down the veins.

Not exactly: The cause of varicose veins is an inherited tendency for you to have weak vein walls and valves in your veins that either don't work properly or didn't form in the first place. As a result, gravity makes blood flow backwards in the affected veins. This produces too much pressure in the veins and they enlarge, becoming what we call varicose. The root cause, though, is heredity, not gravity.

Gravity IS involved!: You are right! gravity alone will not cause varicose veins unless you also have vein insufficiency or improperly functioning valves of your veins which then allow blood to pool in your veins and increase pressure in your leg veins. This increased pressure causes the veins to get thicker and bulge.

Newton's thick skin: An apple hit newton on the head. If newton had sat under apple trees too often, he would need thick skin! and he had better have strong veins too! lucky people inherit genes for strong veins, but 15% of people don't. Gravity pressurizes vein walls and the weaker veins can't take the stress- they give out and dilate! one can't change genetics, but fight back with lifestyle and compression socks!

Bad valves: Varicose veins are caused by valve problems that allow blood from deep high-pressure veins to enter low-pressure veins just under the skin. These veins enlarge, (varicose), leak fluid through the walls (swelling), letting blood through (discoloration) and finally nutritious arterial blood cannot enter an area of the skin resulting in ulcers. It is treated by laser ablation.