BLOOD CLOTTING (COAGULATION)

Blood clotting, also called coagulation of blood plugs ruptured vessels to stop bleeding. Clotting is a complicated process. It involves a series of chemical reactions. Blood clot formation and tightening takes less than an hour.
When a blood vessel is damaged the clot formation is initiated, as soluble fibrinogen forms an insoluble mesh of fibrin.
FIBRINOGEN is an inactive plasma protein, synthesised by the liver. Once activated, it forms a blood clot.
Blood clot forms around the platelet plug.
Blood clotting helps the body to maintain fluid homeostasis, as severe bleeding is life-threatening.
The four essential components critical to coagulation are: 1. Prothrombin, 2. Thrombin, 3. Fibrinogen, 4. Fibrin

Blood Clot Formation

Blood vessels are punctured.
Vessels and platelets are stimulated to release prothrombin activator.
Conversion of prothrombin (a plasma protein) is activated into thrombin (an enzyme)
Thrombin speeds up the conversion of a soluble plasma protein, fibrinogen, into long insoluble threads of a protein called fibrin (forms the threads of the clot)
Fibrin fragments join end to end, forming long threads of fibrin.
Fibrin threads wind around the platelet plug in the damaged area of the blood vessel, forming an interlocking net of fibers.
Since blood flows through the fibrin net, red blood cells get trapped.
Thus the mass of fibrin, platelets, and trapped red blood cells squeezed together to make the initial clot, and reduces the flow of blood at the wound site.