Blood Clot
Three stages of blood clotting are -
Stage 1; Formation of prothrombin activator
Stage 2; Conversion of prothrombin into enzyme thrombin
Stage 3: Conversion of Fibrinogen (soluble) to fibrin (insoluble)
Stage 1; Formation of Prothrombin Activator
Formation of prothrombin activator; prothrombin can be formed in 2 ways-
1. Intrinsic pathway
2. Extrinsic pathway
1. Intrinsic pathway (5-10 min) inside vascular system
After comming in contact with collagen fibres or rconnective tissues inside blood, it will lead to activation of-
Factor XII
Factor XI
Factor XII + Factor XI
Factor IX
Factor VIII
Factor VIII + Calcium ion + Factor III
Factor X
Factor V
Factor X + Factor V
Prothrombin activator/Prothrombinase
2. Extrinsic pathway (15-20sec)
Activated through tissue factor released by endothelial cell after external damage.
Tissue damage
Tissue thromboplastin activates -
(Factor III)
Factor VII
Factor X
Factor V
Factor X + Factor V
Prothrombin activator + Prothrombinase
Stage 2; Conversion of prothrombin into enzyme thrombin
Conversion of Prothrombin into enzyme thrombin
Prothrombin (Factor II) - Prothrombinase + calcium ions - Thrombin
Stage 3; Conversion of Fibrinogen (soluble) to fibrin (insoluble)
Conversion of fibrinogen (soluble) to fibrin (insoluble)
Thrombin acts as catalyst,
Fibrinogen (factror II ) - Thrombin - Insoluble fibrin
Fibrin
Traps th blood cells
Forms the blood clot
Clot Retraction
Clot retraction is tightening of fibrin clot, with in few minutes after a clot is formed it begins to contract. This activity also assist the repair processes.
Fibrinolysis
Physiological mechanism that dissolves clots is called fibrinolysis.
After clot has formed, the process of removing it and healing the damaged blood vessels begins.
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