Intro Flashcards
What is haemostasis?
The arrest of bleeding and maintenance of vascular patency
4 components of normal haemostatic system?
Formation of platelet plug (Primary)
Formation of fibrin clot (Secondary)
Fibrinolysis
Anticoagulant defence
How are platelets formed?
From budding on megakaryocytes in the bone marrow
wht happens when endothelial damage occurs?
Collagen is exposed and releases VWF and other proteins to which platelets have receptors
Platelets attach and secrete chemicals leading to aggregation
Consequences of platelet plug failure?
Bruising and purpura
Mucosal bleeding
Intracranial haemorrhage
Retinal haemorrhages
Screening test for primary haemostasis?
Pt count
How is a fibrin clot formed?
Thrombin formed from prothrombin via factor V/Xa
Thrombin converts fibrinogen into fibrin
Causes of fibrin clot failure?
Clotting factor deficiencies eg haemophillia
Multiple clotting factor deficiency eg disseminated intravascular coagulation
Increased fibrinolysis
How does fibrinolysis occur?
Plasminogen is converted into plasmin by tissue plasminogen activator
Plasmin breaks down fibrin into fibrin degradation products
Screening tests for fibrin clot formation?
Prothrombin time
Naturally occuring anticoagulants?
Serine protease inhibitors
Protein C and S
What is thrombophilia?
Deficiency of naturally occuring anticoagulants, increased tendency to develop venous thrombosis
