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7 Cards in this Set
- Front
- Back
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Two Clotting Pathways
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Intrinsic pathway
So named because everything necessary for it is in the blood. Extrinsic pathway So named because a cellular element outside the blood is needed. This “outside element” is the so-called tissue factor. |
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Anticlotting Systems- To prevent hypercoagulability
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-Tissue factor pathway inhibitor (TFPI) a plasma protein
Binds to tissue factor VIIa complexes and inhibits these complexes to generate factor Xa -Thrombomodulin Thrombin binds and loses all clot-producing effects (see Fig. 12-78) in text -Antithrombin III Inactivates thrombin and other factors by binding to heparin, a substance present on surface of endothelial cells |
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Tissue factor pathway inhibitor (TFPI)- an anticlotting system
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-a plasma protein
-binds to tissue factor VIIa complexes and inhibits these complexes to generate factor Xa |
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Thrombomodulin- an anticlotting system
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-thrombin binds and loses all clot-producing effects
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Antithrombin III- an anticlotting system
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-inactivates thrombin and other factors by binding to heparin, a substance present on surface of endothelial cells
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Thrombin
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-an enzyme that catalyzes a reaction in which several polypeptides are split from molecules of the large rod-shaped plasma protein fibrinogen.
-The still-large fibrinogen remnants then bind to each other to form fibrin. -The fibrin is stabilized and strengthened by covalent bond linkages (catalyzed by factor XIIIa) |
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Role of liver in clotting
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-liver synthesizes bile salts, which go to the GI tract and it absorbs vitamin K.
-the vitamin K in the blood goes back to the liver and synthesizes clotting factors -clotting factors are now in the blood -vitamin K is required for the synthesis of prothrombin |
