Why veins are visible through the skin ?

1 Answer
Oct 12, 2014

Not all veins are visible through the skin. The veins you see are called superficial veins. They are not paired with an artery as deeper veins are. The superficial veins, return only about 10% of the total blood in the leg.

They are very important in that they can help cool the body when it becomes too hot. Blood from the deeper veins are shunted into the superficial ones to allow for heat to leave.

Superficial veins
These are not as important as the deeper ones are as they carry less blood and some are removed by "stripping". Often this is done with varicose veins. These veins can have clots which can travel to the lungs and cause one to collapse.

Varicose veins
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The illustration shows how a varicose vein forms in a leg. Figure A shows a normal vein with a working valve and normal blood flow. Figure B shows a varicose vein with a deformed valve, abnormal blood flow, and thin, stretched walls. The middle image shows where varicose veins might appear in a leg.