What is Haemostatic Mechanisms?

Haemostatic mechanisms like contraction of blood vessels and clotting mechanism (coagulation) help to prevent blood loss during accidents. Contraction of blood vessels causes decrease in blood flow, but clotting is more important for preventing further loss of blood.

Coagulation is a complex process by which the blood forms clots to block and then heal a wound and stop the bleeding. It is a crucial part of hemostasis, stopping blood loss from damaged blood vessels. In hemostasis a damaged blood vessel wall is plugged by a platelet and a fibrin-containing clot to stop the bleeding, so that the damage can be repaired.

A platelet is a disc-shaped element in the blood that is involved in blood clotting. They aggregate (clump together) during normal blood clotting. Fibrin is. an insoluble protein involved in blood clotting. Fibrin is deposited around the wound in a form of mesh to strengthen the platelet plug.

The whole thing dries and hardens (coagulates) so that the bleeding stops and the wound then heals. Fibrin is developed in the blood from a soluble protein, fibrinogen. Clot after sometime undergoes shrinkage through which a clear, faintly straw colored fluid called the serum is visible. Due to the absence of fibrinogen, the serum does not clot. Clot contains no cell, but it is a phenomenon of plasma. The clotting rate of lymph is slow.