Deep vein thrombosis (DVT) is a blood clot (thrombus) in a deep vein, usually in the legs. These clots require medical care right away. These clots are dangerous because they can break loose, travel ...

For example, a capillary is microscopically thin to allow gases to exchange, the arteries are tough and flexible to cope with high pressure blood flow and the veins contain valves to prevent the ...

The lighter skin of the nobility made their veins appear blue under the surface, giving the impression that their blood itself was blue. The term "blue blood" became a metaphor for noble birth and ...