Blood Clotting

Injury

(Damaged tissue)

When PLATELETS come into contact with damaged tissue they react/are released.

THROMBOPLASTIN (globular protein enzyme) is released along with serotonin (5HT) that restricts the release of the blood to minimise blood loss.

Thromboplastin catalyses the conversion of PROTHROMBIN (large protein in blood) to THROMBIN

Vit. K and Ca2+ must be present in correct concentration for this to happen

The thrombin acts on another protein called FIBRINOGEN (soluble) and catalyses its conversion into FIBRIN (insoluble fibrous protein that traps everything)

Platelets and blood cells pouring from the wound get trapped in the fibrin mesh causing a clot

Special proteins in the structure of platelets contract, making the clot tighter. This stops infection from entering the wound.