thromboplastin(redirected from extrinsic thromboplastin)
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tissue thromboplastin factor III, a coagulation factor derived from several different sources in the body, such as brain and lung; it is important in the formation of extrinsic prothrombin converting principle in the extrinsic pathway of coagulation. Called also tissue factor. See also activated partial thromboplastin time.
A substance present in tissues, platelets, and leukocytes necessary for the coagulation of blood; in the presence of calcium ions thromboplastin is necessary for the conversion of prothrombin to thrombin, an important step in coagulation of blood. It is now generally believed that thromboplastin activity may be developed through blood (intrinsic) or tissue (extrinsic) systems. Tissue thromboplastin (factor III) interacts with factor VII and calcium to activate factor X; active factor X combines with factor V in the presence of calcium and phospholipid to produce thromboplastin activity (also commonly called thromboplastin).
A protease that converts prothrombin to thrombin in the early stages of blood clotting. Also called thrombokinase.
thromboplastinBlood clotting factor III, an obsolete term referring to what is now known to be several blood clotting factors operating together.
thromboplastinsee BLOOD CLOTTING.
A protein in blood that converts prothrombin to thrombin.
Mentioned in: Prothrombin Time