Lecture 18 - Thrombosis Flashcards
Endothelium preventing haemostasis?
physically insulating tissue from blood, enzymatic and chemical inhibitors (NO), antithrombin production
Haemostasis is co-operation of?
endothelial cells, platelets, coagulation cascade
Injury to endothelial cells leads to?
endothelin release (vasoconstriction), exposed underlying tissue activates platelets and coagulation cascade, von Willebrand factor release promoting platelet adhesion to ECM, thromboplastin release (cascade)
Platelet activation?
secrete chemical signals promoting vasoconstriction and aggregation
Effects of lowered platelets?
purpura (bleeding from skin capillaries) and haemorrhage
Compositions of thrombi?
fibrin, platelets, entrapped red and white blood cells
Blood clot different because?
formed in static blood, primarily coagulation system, w-out platlet and wall interaction, composed of random mixture of blood cells suspended in serum proteins
Virchow’s Triad of Thrombosis?
endothelial injury, abnormal blood flow, hypercoagulability
Causes of changed blood flow - artery?
turbulence is key - narrowing, anuerysms, MI, abnormal cardiac rhythm
Causes of changed blood flow - veins?
stasis is key - right sided failure, compressed and varicose veins, blood viscosity
Effects of chsnged blood flow?
platelet-endothelium contact, decreased removal/delivery of pro/anti-coagulant factors
Natural anticoagulants?
antithrombins, proteins C and S (vitamin K dependent), tissue factor pathway inhibitor, fibrinolytic cascade
Emboli?
intravascular mass carried by blood flow from its point of origin to a distant site
Effects of emboli?
stenosis leadingg to occlusion, leg vein -> pulmonary artery causing pulmonary infarction, mural thrombus -> systemic
