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).
thromboplastin/throm·bo·plas·tin/ (-plas´tin) coagulation factor III.
tissue thromboplastin coagulation factor III.
A protease that converts prothrombin to thrombin in the early stages of blood clotting. Also called thrombokinase.
a plasma protein that initiates the clotting process by converting prothrombin to thrombin in the presence of calcium ions.
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
thromboplastin; thrombokinase catalyst (in tissues, platelets, leukocytes) which, in presence of calcium ions, aids conversion of prothrombin to thrombin
n a substance necessary to the coagulant activity of tissue extracts; also has been referred to as the direct activator of prothrombin and as a substance from plasma, platelets, and tissues that initiates thromboplastic activity in blood coagulation. See also thromboplastin, extrinsic.
n See thromboplastin, extrinsic.
thromboplastin, cofactor of,
n See factor V.
n a direct prothrombin activator formed by the interaction of brain extracts, factors V and VII, and factor IV calcium (Ca++).
n tissue thromboplastin.
thromboplastin, intrinsic (plasma thromboplastin, intrinsic prothrombin activator),
n a prothrombin activator formed from interaction of blood coagulation factors V, VIII, IX, and X and factor IV calcium (Ca++) with a foreign surface.
thromboplastin, partial time (PTT),
n a blood test used to determine von Willebrand disease, hemophilia, and to monitor anticoagulant medications. Normal coagulation time is 68 to 82 seconds. An updated form of the test, activated partial thromboplastin time (APTT), is replacing PTT.
n a factor in tissue extract responsible for coagulation of blood.
a substance in blood and tissues which, in the presence of ionized calcium, aids in the conversion of prothrombin to thrombin. Extrinsic and intrinsic thromboplastin are formed as the result of the interaction of different clotting factors; the factors that combine to form extrinsic thromboplastin are not all derived from intravascular sources, whereas those that form intrinsic thromboplastin are.
activated partial thromboplastin time
see activated partial thromboplastin time.
the prothrombin activator formed as a result of interaction of coagulation factors III, VII, and X which, with factor IV, aids in the formation of thrombin.
thromboplastin generation time (TGT)
evaluates the first stage in blood coagulation by measuring the efficiency of prothrombinase formation.
the prothrombin activator formed as a result of interaction of coagulation factors V, VII, IX, X, XI and XII and platelet factor 3 (PF-3), which, with factor IV, aids in the conversion of prothrombin to thrombin.
plasma thromboplastin antecedent (PTA)
clotting factor XI; deficiency occurs in cattle and dogs, causing mild to severe bleeding tendencies called hemophilia C.
plasma thromboplastin component (PTC)
see activated partial thromboplastin time.
factor III, a material derived from several sources in the body (e.g. brain, lung), and is important in the formation of extrinsic prothrombin converting principle in the extrinsic pathway of blood coagulation. Called also tissue factor.