Each 2.54 square centimetre (a square inch) of human skin has six metres (20ft) of blood vessels. Veins hold about 65 per cent of the body's blood and have one-way valves tohelp blood move.

Plasma is a straw-coloured liquid that makes up just over half the volume of blood. You have about 5.5 litres of blood in your body That’s ... neck and upper arm. The pulse rate is expressed ...

Decreased venous oxygen saturation was also present in vapers whether or not the e-cigarettes contained nicotine.