Question

What are the 3 stages of blood clotting?

Answer 1

Blood clotting is the process by which blood changes from a liquid to a solid to stop bleeding from wounds. The mechanism of blood clotting involves activation, adhesion and aggregation of platelets along with deposition and maturation of fibrin at the site of blood vessel damage. When the damaged tissue heals, the clot dissolves and the blood takes back the platelets and cells of the clot. Blood clotting happens through three major stages.

Complete answer:

1. The first stage of blood clotting is Vasoconstriction: After the injury, the blood vessel shrinks and decreases the blood loss from the damaged site. During the injury, the blood vessels are cut and the collagen is exposed. The platelets adhere to this collagen, get activated and secrete vasoconstrictor substances that immediately constricts the blood vessel.

2. The next stage is the Platelet plug formation: The activated platelets attract more platelets to the wound site by secreting adenosine triphosphate and thromboxane-A. They aggregate together to form a plug and close the ruptured blood vessel thereby preventing blood loss.
3. The final stage of blood clotting is the Coagulation of blood: This is done by the fibrin fibers. Fibrin is produced from its inactivated form fibrinogen by the action of clotting enzyme, thrombin. The fibrin fibers then form long fibrin threads which entangle the platelets to build up a spongy mass. The spongy mass hardens and contracts to form the blood clot. Fibrin-stabilizing factor helps in the hardening process.

Note:
There are several clotting factors involved in the blood clotting process. If blood clots are formed in inappropriate locations, it can be life threatening. These clots can block the arteries in the heart and cause heart attacks. In the brain it causes strokes. There are drugs that can remove blood clots in unwanted locations. They are Tissue plasminogen activator (TPA) and Streptokinase enzyme.