Thrombosis 2 Flashcards
What factors favour thrombosis? (virchows triad)
- Endothelial injury
- Abnormal blood flow- Stasis
- Hyper-coagulation of blood
What is thrombosis?
Formation of blood clot in a blood vessel, restricting blood flow
How do platelets become activated in thrombosis?
Endothelial damage exposes collagen to the outer surface. Collagen binds to Glycoprotein Ia/IIb on platelets. Increase in platelet integrins. Glycoprotein Ia/IIb binds to fibrinogen: brings platelets together. Activated platelets release granules to attract other platelets: thromboxaneA2(TXA2), Platelet activating factor (PAF), ADP.
What substance formation marks the endpoint of coagulation?
Fibrin- Brings platelets together in a fine mesh to form a solid stable blood clot.
What are some common coagulation factors involved in a typical cascade?
Factor IIa- Thrombin Factor V, X Factor II, XIII- Activate fibrinogen. Thrombin- converts fibrinogen to fibrin.
Why is Vitamin K important?
How can liver disease affect it?
What drug inhibits Vitamin K?
Needed to make coagulation factor II, VI, IX, X.
Liver disease- No vitamin K produced as it is ususally stored in liver. hence no factors produced
Warfarin- Inhibits vitamin K from producing factors
What disease can be commonly associated with thrombosis?
Hypertension. High pressure blood flow can cause damage to the endothelium more easily.
Why is arterial thrombosis uncommon?
Blood stasis uncommon
Arterial blood flow is high (diff to pressure) so pro-coagulation materials are moved along before they can bind to the endothelium to do anything.
What is atherosclerosis and when can thrombosis occur in relation to it?
Formation of plaques on the surface of the endothelium, most commonly due to hypertension. Turbulent flow= increased endothelial damage
Plaque rupture= thrombosis formation
What are some common diseases where thrombosis/emboli to occur?
- Cerebral infarction
- Carotid atheroma
- Myocardium infarction
- Aortic aneurysm
- DVT/ peripheral vascular disease
What is the difference between stable/ unstable angina?
Stable- exercise induced Unstable- Plaque ruptures, causing thrombosis
What is Poiseuille’s law?
Small narrowing in a blood vessel can greatly affect the decreased blood flow to the tissues.
What can be some other causes of endothelial injury?
- Toxins - Smoking - Infectious agents
What is an autoimmune disease causing endothelial injury?
Primary vasculitis- Autoimmune disease characterised by inflammation of the vessel walls.
What are the effects of Turbulence?
- Endothelial damage
- Stasis
What is stasis? What are its effects?
Blood flow usually smooth and laminar. In stasis, blood flow slows down. Effect- Increased platelet contact with endothelial wall
Where does stasis occur? why?
Veins. Due to:
- Valves not functioning
- Venous insufficiency (insufficient flow of blood through veins causing pooling of in the legs).
What is the role of plasmin?
Breaks clots
What are some Anti-clotting proteins?
- Protein C,
- Protein S
- Anti-thrombin III
What is factor V Lieden hyper-coagulability?
-Mutation in Point of factor V - Protein C, S, anti thrombin III deficiency
What are some secondary causes of hyper-coagulability?
- prolonged immobility -Cancer -MI,AF Low risk: the pill, smoking, renal disease, cardiomyopathy
What is an embolism?
Dislodged thrombus. Travels around vascular system until it gets stuck
What is the difference between ischaemia and infarction?
Ischaemia- insufficient blood supply Infarction- tissue death due to ischaemia
Which common branching vessels often get thrombus?
- Coronary arteries - above bifurcation of aorta - origin and division of carotid arteries - renal artery - superior mesenteric artery
