Basic Blood Coagulation Physiology, Lab Tests and Disorders Flashcards Preview

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Flashcards in Basic Blood Coagulation Physiology, Lab Tests and Disorders Deck (10):

How does primary haemostasis work?

- Injury causes vessels to constrict to reduce blood flow, mediated by endothelin - Biochemistry of vessel walls change and negatively charged platelets are attracted to the damaged surfaces - Platelets adhere to exposed collagen via vWF - vWF combines with platelet surface receptor glycoprotein 1B9 and links platelet to collagen - GP6 binds as well leading to further platelet activation - Activation causes platelets to release granule contents (ADP and thromboxane) enhancing the effect - Binding of GP6 to collagen activated GPIIb/IIIa which binds to fibrinogen, acting as a bridge between platelets


How is primary haemostasis assessed?

- Bleeding time - FBC (platelet count) - Platelet function


How is secondary haemostasis assessed?

- PT (stimulates activation via extrinsic pathway) - aPTT (stimulates activation via intrinsic pathway) - TCT (conversion of fibrinogen to fibrin)


What is DIC?

- Process involves systemic activation of coagulation leading to intravascular deposition of fibrin and thrombosis as well as depletion of platelets and coagulation factors - Causes include sepsis, malignancy, massive haemorrhage, severe trauma and pregnancy complications


What is Haemophilia A?

- Factor VIII deficiency - X-linked inheritance - Prolonged aPTT - Treated with desmopressin


What is Von Willebrand disease?

- AD with variable penetrance - Mucosal type bleeding pattern - Reduced vWF +/- reduced platelet aggregation +/- reduced VIII


What is Lupus anticoagulant?

- Phospholipid dependent antibody - aPTT prolonged


What is antiphospholipid syndrome?

- Disrupts annexin V shield - Exposes excess phospholipid


What is thrombophilia?

- Inherited - Deficiencies of natural anticoagulants (antithrombin, Protein C, Protein S)


How does secondary haemostasis work?

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