Haemostasis Flashcards
Define haemostasis
Vasoconstriction
Platlet plug - activated by collagen, ADP, thromboxane A2 and thrombin.
Clotting cascade activates by intrinsic or extrinsic pathway
Outline steps of clotting cascade
Int XII XI IX--------VII X--------V
Ext
III
VII
X——-V
Common
X
Thrombin
Fibrin
List common causes of thrombocytopenia
Low platelets from
- decreased platelet production
- decreeasted platelt survival (immunological)
- sequestration -spleen
- dilutional (massive transfusion)
Thrombocytopenia shows what in PT and APTT
PT- normal
APTT normal
Its the bleeding time thats long
What tests are done in a coagulation screen?
Platelet count, bleeding time, APTT, PT and INR
Outline the function of the vessel wall in haemostasis
Tunica media contracts
endothelium traps platelets
Secretes thrombomodulin and plasminogen as anti clotting
balances with Von willebrand and tissue factor.
What is Christmas disease?
Factor 9 deficiency
How is haemophilia A inherited?
X linked recessive
What is thrombophilia?
Inherited or acquired conditions that pre-dispose to thrombus formation. e.g. V leiden or an antithrombin deficiency.
What is DIC?
Thrombohaemorrhagic disorder secondary to other pathologies.
Multiple microthrombosis occur which uses up all the clotting factors and breaks down into d-dimers.
Gram negative sepsis and O+G complications are common causes.
Patients need treatment for the primary cause as well as possible fresh frozen plasma transfusion.
What is responsible for fibrinolysis?
Plasmin
Outline the function of the vessel wall in haemostasis
Tunica media contracts
endothelium traps platelets
Secretes thrombomodulin and plasminogen as anti clotting
balances with Von Willebrand and tissue factor.
