Thrombosis Flashcards
1) Diagram the intrinsic, extrinsic and “new” coagulation pathways.
intrinsic (in blood): Kalkrein + Factor 12 > Factor 11> Factor 9 +Factor 8 > Factor 10 + 5 > Factor II (prothrombin) > factor 13
extrinsic (in tissue): Factor 7 > Factor 7a (Tissue Factor) > Factor 10 (everything else same). especially effected by Vitamin K deficiency (Factors 2,7,9,10, are K dependent)
New:
2) Explain how PT and PTT tests are performed.
blood in lab. If PTT does not correct after mixing with fresh normal blood, anticlotting factors present. If deficiency in something will correct.
3) Name the four stages of hemostasis and explain what is occurring in each.
contraction of vessel - platelet aggregation - activation of coagulation cascade, thrombus and anti-thrombolis events ( endothelium release of RBCs, t-PA, thrombomodulin, etc)
4) Explain the “3 A’s” associated with the role of platelets in hemostasis.
adhesion due to Von Willebrands factor
activation - change in surface protein GPIIa
aggregation of fibrinogen due to cross-linking with GPIIb/IIIa on platelets
5) Name three functions of von Willebrands factor.
adhesion - conformational change leads to binding to GP1a
aggregation: binds platelet GPIIB/IIa
Factor 8 binding to site of hemorrhage
6) Explain the roll of factor XIII in coagulation.
cross-links lysine and glutamine chains to stabilize fibrin clot
7) Name the three inherent anticoagulant systems/mechanisms in the blood.
antithrombin: binds heparin, thrombin to neutralize Factors 9/10/11/12
thrombomodulin release from endothelial cells that binds Protein C and thrombin to inactive Factor 5 & 8,
fibrinoyltic systems: plasminogen from liver
8) Identify four types of hemophilia and the factors that are deficient in each.
Von Willebrands disease: most common. deficiency in VW
Hemophilia A: deficinency in factor 8
Hemophilia B: factor 9 deficiency
Hemophilia C: factor 11 deficiency. rare.
9) Name the three components of “Virchow’s triad” active in thrombosis.
endothelial injury, abnormal blood flow, hyper-coagulation
10) Explain the abnormality present in factor V Leiden hypercoagulability.
activated protein C resistance due to cleavage of receptor on Factor 5
11) Discuss the etiological, clinical, and laboratory findings associated with DIC.
inappropriate coagulation in vessels leads to consumption of pro-coagulants leading to bleeding.
elevated D-dimer (fibrinogen degradation), thrombocytopenia, prolonged coagulation time, fragmented red blood cells.
associated with: obstetrics (rare), sepsis, leukemias, viremia
12) Calculate an INR from a patient’s PT value and the normalized PT value.
(PT/mean PT)^INS (standardization of thromboplastin factors in that particular lab)
13) Explain the mechanism behind three forms of antiplatelet.
Coumadin: Vitamin K antagonist decreases 2, 7,9, 10
Heparins: inhibit thrombin action (factor 2)
t-PA, streptokinase: lyse clot
