MoD - Haemostasis Flashcards
How do blood vessels react to blood loss
They contract to limit the blood loss
What does successful haemostasis depend on?
Vessel wall
Platelets
Coagulation
Fibrinolytic system
How do platelets react to damaged vessel walls?
They adhere to the damaged wall and each other - forming a platelet plug. They also stimulate coagulation factors
What is Coagulation?
The blood clotting cascade in response to vascular injury
What is an example of a thrombin inhibitor?
Anti - thrombin 3
How do thrombin inhibitors prevent clotting?
This prevents the formation of fibrin from fibrinogen
How is fibrin broken down?
By fibrinolysis by the conversion of plasminogen to plasmin via plasminogen activators (ie streptokinase, tPa)
What is thrombosis?
The formation of a solid mass of blood within the circulatory system
What are the three ways a thrombosis can form (give details)
Abnormal vessel wall (atheroma, direct injury, inflammation)
Abnormal blood flow (stagnation, turbulence)
Abnormality of blood components ( smokers, post partum)
What is the appearance of an arterial thrombus?
Pale, granular, lines of zahn
What is the appearance of a venous thrombus?
Soft, gelatinous, deep red, higher cell content
What are the 5 outcomes of a thrombus?
Lysis Propagation (progressive spread) Organisation (fibrous repair) Recanalisation ( one or more channels formed) Embolism (breaks off)
What are the effects of an arterial thrombi?
Ischaemia, infarction
What are the effects of a venous thrombi?
Congestion, oedema, (ischaemia, infarction) once the other two begin to compress arteries
What is embolism?
The blockage of a blood vessel by solid liquid or gas at a site different to its origin
