How does blood clot?
Blood is essential for the human body. The body of an average, healthy person has about six liters of blood moving inside it. Loss of too much blood can kill a person, although a healthy person can still live after loosing as much as one third of the body’s blood. When an area or port of the body gets cut by any sharp instrument, blood oozes out. But soon the blood dries and the flow stops.
Coagulation or clotting of blood is one of the nature’s way of protecting the human body. Each person’s blood clots at a slightly different rate. And there are some people whose blood clots very slowly or not at all. This condition is called hemophilia and can be dangerous unless constant precaution is taken.
The first thing that happens when blood starts clotting is the appearance of fibrin in the blood. Very fine threads of fibrin form a kind of net by criss crossing each other in all directions. They trap the blood cells which soon solidify. The fibrin threads are firm and elastic. When the damaged cells of the wound are replaced the outer layer of cells or the scab falls off.
The blood flowing inside the body does not and must not clot. Clotting of the blood inside the circulatory system is as dangerous as its not clotting outside a wound. A substance called heparin in the body helps blood remain in flowing condition. Blood does not clot when it remains in contact with the smooth walls of the blood vessels. An injury or contact with a rough surface is essential to start the clotting process.