Blood coagulation

Blood coagulation is a complex process that helps prevent excessive bleeding when the body's blood vessels are injured. The process is also known as clotting. It involves a series of chemical reactions that result in the formation of a clot, which is a mass of blood cells and fibrin strands that seals the injured blood vessel.

Process of Blood Coagulation

The process of blood coagulation is initiated when blood vessels are damaged. The damaged cells release chemicals that start the clotting process. This process involves several steps:

1. Vasoconstriction: Immediately after the injury, the blood vessel constricts to limit blood flow.
2. Formation of the platelet plug: Platelets in the blood stick to the damaged area of the vessel and to each other, forming a plug.
3. Coagulation cascade: A series of chemical reactions, known as the coagulation cascade, leads to the formation of a fibrin clot. This involves the activation of clotting factors, proteins in the blood that are produced by the liver.

Coagulation Factors

There are 13 known coagulation factors, which are designated by Roman numerals (I through XIII). The coagulation factors interact in a complex sequence of chemical reactions to form a fibrin clot. The process is regulated by various inhibitors that prevent the clot from growing too large.

Disorders of Blood Coagulation

Disorders of blood coagulation can lead to excessive bleeding or excessive clotting. These include:

1. Hemophilia: A genetic disorder that impairs the body's ability to make blood clots.
2. Von Willebrand disease: A genetic disorder caused by missing or defective von Willebrand factor, a clotting protein.
3. Deep vein thrombosis: A blood clot that forms in a vein deep in the body, often in the leg.

See Also

• Hemostasis
• Thrombosis
• Anticoagulant
• Prothrombin time