Intrinsic vs Extrinsic Pathways in Blood Clotting Within about 15 seconds, it completes blood coagulation. Extrinsic pathway is quicker than intrinsic pathway. Once prothrombin activator is formed, the common pathway starts and blood coagulation proceeds. Factor Xa is the prothrombin activator which is responsible for the conversion of prothrombin into thrombin. Factor IXa activates factor X into factor Xa. Factor VIIa activates factor IX into IXa. But when there is an injury, tissue factor exposes to blood and activates factor VII into factor VIIa. Under normal conditions, blood is not contacted or exposed to these tissue factors. Tissue factor is the main component which activates the extrinsic pathway of blood clotting. Tissue factor is a protein found in many tissues of the body, including brain, lungs, and placenta. These external factors release a complex of several factors which is collectively known as tissue factor or tissue thromboplastin or factor III. This system is activated by vascular tissue trauma or surrounding extra-vascular tissue trauma. But it is an important process in organisms.įigure 02: Intrinsic and Extrinsic Pathways of Blood Clotting What is Extrinsic Pathway in Blood Clotting?Įxtrinsic pathway is another way of blood coagulation. Intrinsic pathway of blood clotting is a slow process which completes within several minutes. Thrombin catalyzes the polymerization of fibrinogen into fibrin, which is the basic component of the blood clot. When prothrombin activator is activated, it facilitates the conversion of prothrombin into thrombin. Intrinsic pathway enters into a common pathway of blood coagulation after activating prothrombin activator. Activated factors IX, VIII, and platelet phospholipids collectively activate the factor X or the prothrombin activator. Activated factor IX, in turn, activates the factor VIII. Activated factor XI then activates the factor IX. When factor XII contacts with the exposed collagen, it activates and catalyzes the activation of factor XI. Intrinsic pathway begins with the blood trauma and involves factors XII, XI, IX and VIII. Hence this process is named as ‘intrinsic pathway.’ Components required for intrinsic pathway are entirely contained within the blood or the vasculature. Intrinsic pathway is a type of blood clotting pathway which is activated by a trauma in blood or when blood is exposed to a subendothelial collagen. What is Intrinsic Pathway in Blood Clotting? As mentioned above the difference between intrinsic and extrinsic pathways in blood clotting is their initiation factors. Intrinsic and extrinsic pathways in blood clotting initiate and progress towards activating prothrombin activator when there is an injury in the blood vessel. Prothrombin activator is activated by the two blood clotting pathways: intrinsic and extrinsic pathways. The conversion of prothrombin to thrombin is done by prothrombin activator or the factor X. Thrombin enzyme catalyzes the polymerization of insoluble fibrin from fibrinogen. The formation of a stable blood clot is facilitated by an enzyme called thrombin. Side by Side Comparison – Intrinsic vs Extrinsic Pathways in Blood Clotting in Tabular FormĪ blood clot consists of fibrin, platelets and blood cells. Similarities Between Intrinsic and Extrinsic Pathways in Blood ClottingĦ. What is Extrinsic Pathway in Blood Clottingĥ. What is Intrinsic Pathway in Blood ClottingĤ. The extrinsic pathway starts when there is a vascular tissue trauma or trauma surrounding tissues. The intrinsic pathway starts when there is a trauma in blood or when blood is exposed to a collagen. The key difference between intrinsic and extrinsic pathways in blood clotting is their initiation factors. Coagulation cascade has two pathways known as intrinsic and extrinsic pathway. It is a complicated process which occurs via series of activation processes collectively called coagulation cascade. Key Difference – Intrinsic vs Extrinsic Pathways in Blood Clottingīlood clotting is an important process to stop bleeding.
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