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NormalHemostasis

lecture 19 sarode

QuestionAnswer
hemostasis process through which the body stops hemorrhage from a damaged vessel
primary hemostasis process by which plts and vWF initiate clotting. 3 steps: plt adhesion, secretion and plt aggregation
step 1: adhesion of plts GPIb & subendothelial vWF attach to collagen GPIa/IIa -- binds subendothelial collagen
secondary hemostasis clotting factors make cross-linked fibrin network to consolidate the initial plt plug made with primary hemostasis
tertiary hemostasis fibrinolysis and dissolution of the clot
nl plt count 150-450 billion plts/L
step 2: secretion of plts, after adhesion activation of PLA2 to make TXA2; release of alpha granules that contain fibrinogen, vWF and thrombospondin; release of dense granules containing Ca++ & ADP
step 3: aggregation, after secretion GPIIb/IIIa undergoes conformational change to be able to bind fibrinogen with high affinity
After which step does the plt go from discoid to conformation with many dendritic pseudopodia? after initial adhesion (step 1)
plt count that qualifies as thrombocytopenia < 100K per microliter of blood
plt count that puts pt at risk for spontaneous bleeding < 10K per microliter of blood
sx seen with plt dysfunction (thrombocytopathies like von Willebrand dz) mucocutaneous bleeding --> GI bleeds, epistaxis, menorrhagia, petechiae and pupura, urinary tract bleeding
methods for acquired plt dysfunction herbs, fish oils, some dietary supplements, ASA, Plavix
liver makes all coagulation factors except for ______ factor VIII
how does FVIII travel carried and stabilized by vWF in the plasma
coagulation factors are serine protease zymogens that must be cleaved and activated
vitamin K dependent factors Factors II, VII, IX and X must be gamma carboxylated so Ca++ can associate and they can become fully active, capable of binding phospholipid surfaces
heat-labile coagulation factors V and VIII
hemophilia A factor VIII deficiency (1:5000)
hemophilia B factor IX deficiency (1:25,000)
antithrombin's effects are potentiated by what? heparan sulfate (Heparin in clinic enhances thousands fold), dermatan sulfate and chondroitin sulfate
Factor VII has shortest half-life of 3-6 hrs
vonWillebrand dz most common congenital bleeding disorder with mucocutaneous bleeding, decreased Factor VIII binding
Pt on heparin will have abnormally low antithrombin levels
Created by: sirprakes