5 Haemostasis + thrombosis Flashcards
what is the role of vessel wall in haemostasis?
To constrict and reduce blood loss
Wha is the role of platelets in haemostasis?
To adhere together and form platelet plug
What is the role of coagulation system in haemostasis?
to activate the clotting cascade/ and convert inactive proteins to activated form: prothrombin –> thrombin, fibrinogen –> fibrin
What is fibrinolysis and describe the process
Breakdown of fibrin (mesh0, Plasminogen converted to plasmin (breaks down mesh) by streptokinase + t-PA
Which factors control coagulation?
Thrombin inhibitors: 1. anti-thrombin III 2. alpha 1 anti-trypsin 3. alpha 2 macroglobulin 4. proteins C + S deficiency of 1 and 4 leads to thrombosis
Name 4 anti-thombin produced by the endothelium
- Plasminogen activator (breaks down fibrin mesh)
- Prostacyclin
- thombomodulin
- nitric oxide
What is thrombosis?
the formation of a solid mass of blood in the circulatory system DURING LIFE
Name 3 predisposing abnormalities of thrombosis
- Vessel Wall
- Blood flow
- blood components
What abnormalities of vessel wall can cause thrombosis?
Atheroma (fatty deposits, narrowing lumen), direct injury and inflammation (vasculitis)
What abnormalities of blood flow can lead to thrombosis?
Stagnation (stationary flow), turbulence (high resistance)
What abnormal blood components can predispose thrombosis?
smokers (thicker blood, coagulate easier), post- partum (giving birth, need to clot easier), post-operation
What are the 5 outcomes of thrombosis?
Resolution, propagation, organisation, recanalisation, embolism
What is resolution?
Thrombus dissolves (usually v small)
What is propagation?
Thrombus spread + grow in direction of travel e.g. arteries (distal), veins (proximal)
What is organisation?
ingrowth of fibroblast
What is recanalisation?
Small holes created in thrombus to allow blood through, thrombus is still lodging in vessel
What is embolism?
lodging of blood clot blocking blood vessel at site away from origin, by solid / liquid / gas
What is Virchow’s triad?
3 actors contributing to thrombosis: hypercoagulability (clots easily), hemodynamic changes (abnormal blood flow), endothelial injury / disfunction (vessel wall injury)
Name some effects of thrombosis
ischaemia + infarction, in veins can cause oedema and congestion
What is embolism?
Blockage of blood vessel by solid/ liquid/ gas at site away from origin
What is pulmonary embolism?
Embolism in veins going to lungs
Name some examples of venous + arterial embolism?
heart –> artoa –> other arteries
arteromatous carotid arteries –> brain
artheromatous abdominal aorta –> arteries in the legs
What is deep vein thrombosis?
Blood clot in deep veins, commonly in legs
What are predisposing factors of deep vein thrombosis?
immobility (e.g. bed-bound), post-op, post-partum, oral contraceptives, severe burns, cardiac failure, disseminated cancer
also in long journeys where legs are compressed
What would be used in prevention of thromboembolic disease?
prophylaxis
what would be used to treat thromboembolic disease?
IV heparin + oral warfarin
What are other types of embolisms that can occur? (apart from deep vein and venous + arterial)
air, amniotic fluid, fat, medical equipment, tumour cells
Name the 3 types of haemophilia and the defects they are linked to
haemophilia A - factor 8 deficiency
haemophilia B - factor 9 deficiency
haemophilia C - factor 11 deficiency
all part of intrinsic pathway, leading to blood clots not formed as readily and easy bruise
What is disseminated intravascular coagulation?
Widespread activation of clotting cascade leading blood clot in small vessels
What is thrombocytopenia?
Deficiency of platelets, can’t clot as platelet plug can be form, easily bruises
What is thrombophilia?
Blood clots easily, can increase chances of DVT and or PE
Name some symptoms of pulmonary embolism
shortness of breathe, small peripheral arteries blocked, if recurrent leads to pulmonary hypertension
what is haemostasis?
body’s response to damaged blood vessels’ forms blood clot to stop bleeding
