Clotting doesn’t work in the principal arteries, because the flow of blood is too fierce; any clot would be swept away, which is why major bleeds must be stopped with the pressure of a tourniquet. In severe bleeding, the body does all it can to keep blood flowing to the vital organs and diverts it away from secondary outposts like muscles and surface tissues. That’s why patients who are bleeding heavily turn a cadaverous white and are cold to the touch. Platelets live
