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26 Cards in this Set
- Front
- Back
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What is 'haemostasis'?
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A complex process which causes the bleeding process to stop
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'A complex process which causes the bleeding process to stop' defines...
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Haemostasis
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When blood vessels are damaged, they constrict and platelets adhere to the damaged vascular endothelium by means of a protein called...
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...Von Willebrand Factor (vWF)
Teehee 1320111210 |
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Adherent platelets do not change their shape T/F
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F
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What is the next stage of haemostasis after platelets adhere?
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The coagulation mechanism (Platelets provide a platform for this stage)
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Factor VIII is bound to vWF while inactive in circulation; Factor VIII degrades rapidly when not bound to vWF. Factor VIII is released from vWF by the action of...
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thrombin
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How is coagulation initiated?
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Interaction of membrane bound tissue factor (TF), exposed by vascular injury, with activated plasma factor VII (factor VIIa)
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Tissue factor is always exposed on subepithelial surfaces T/F
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F - it is exposed by vascular injury. Its interaction with activated plasma factor VII initiates coagulation
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It is exposed by vascular injury. Its interaction with activated plasma factor VII initiates coagulation
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Tissue factor
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What are the constituents of the 'prothrombinase complex'?
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Facto Xa, Va, phospholipids and Ca^2+ (The prothrombinase complex results in explosive generation of thrombin - the 'thrombin burst')
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What phase is being described?:
'Thrombin 'back-activates' factor VIII which, with factor IXa on the phospholipid surface, and in the presence of CA2+ activates sufficient factor Xa which then, in combination with Va, phospholipids and Ca^2+ forms the prothrombinase complex' |
The amplification phase
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An insoluble protein that reinforces and stabilises the platelet plug
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Fibrin
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Which vitamin is required for the gamma-carboxylation of a number of terminal amino acid residues in the vitamin _ dependent coagulation proteins?
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Vitamin K
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What are the vitamin K dependent coagulation proteins?
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Factors II, VII, IX and X
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After tissue healing has taken place, the thrombus is dissolved by a process termed...
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Fibrinolysis
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What is the inactive precursor of plasmin?
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Plasminogen
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Which enzyme breaks down the thrombus?
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Plasmin
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Fibrinolysis involves the generation of an enzyme which breaks down the thrombus. What is this enzyme called?
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Plasmin
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What is a TFPI?
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A 'tissue factor pathway inhibitor' (Prevents uncontrolled coagulation)
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An inhibitor that inactivates the initiation phase of coagulation by forming a quaternary complex with factor VIIa, Xa and tissue factor
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Tissue factor pathway inhibitor (TFPI)
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Which phase of coagulation does TFPI inhibit?
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The initiation phase (forms complexes with factors including tissue factor)
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How does antithrombin (AT) prevent uncontrolled coagulation?
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It inactivates thrombin and activated factor X (factor Xa)
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It inactivates thrombin and activated factor X (factor Xa)
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Antithrombin (AT)
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How does the protein C/S system prevent uncontrolled coagulation?
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Thrombin binds to an endothelial surface receptor, thrombomodulin, and the resultant activates protein C (PC) to activated protein C (APS). APC exerts its anticoagulant effect by inactivation of activated factor V and factor VIII, with protein S (PS) a cofactor. Both protein C and S are vitamin K dependent proteins
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What are the three ways of preventing uncontrolled coagulation?
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TFPI
Antithrombin Protein C/S system |
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Thrombin converts fibrin into fibrinogen T/F
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F! Thrombin converts fibrinogen into fibrin
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