Blood clots form through a process called blood coagulation, which is the body's natural way to stop bleeding after a blood vessel is injured. When a blood vessel is damaged, the following happens:
- The blood vessel narrows to slow blood flow.
- Platelets (a type of blood cell) stick to the damaged area and to each other, forming a plug.
- Platelets release substances that activate clotting factors—special proteins in the blood.
- These clotting factors trigger a cascade of chemical reactions that convert fibrinogen, a dissolved protein, into fibrin.
- Fibrin strands form a net that traps platelets and red blood cells, creating a stable clot that plugs the vessel to prevent further bleeding.
- After the vessel is healed, the body naturally breaks down the clot.
The formation of a blood clot (thrombus) is regulated but can occur abnormally due to injury, slow or turbulent blood flow, or hypercoagulability (increased tendency of the blood to clot). This abnormal clot formation can block blood vessels and cause health problems like heart attacks or strokes.
