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9 Cards in this Set

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Where is Heparin found?

Naturally occurring in liver, lungs and mast cells





What is the heparin family ?









A family of sulphated muco-polysaccharides


Sulphated give high -ve charge


Come in a range of MW 3-40K


Varying structures: Standard, unfractionated

A family of sulphated muco-polysaccharides




Sulphated give high -ve charge




Come in a range of MW 3-40K




Varying structures: Standard, unfractionated

Consequences of differing molecular structures of heparin ?

Different sizes have different functions




They can be separated out, applied differently

Problems with Heparin?

Poorly absorbed from oral administration




Due to large size of heparin molecules, and its charge




Has to be given IV or subcutaneously




Risk of Haemorrhage




Common to all anticoagulants




Mild case: Cease dosage




Severe case: Complex Heparin with Protamine, Protamine has a +ve charge




Charges bind, clumps with Heparin, unable to be used by body

Action of Heparin

Inhibits action of Thrombin, and Factors X, IX

For Heparin action, what needs to be present?

Antithrombin III (ATIII)




ATIII is a protease inhibitor




Normally it opposes coagulation

Mechanism of Heparin action?

hepatin binds to both ATIII and thrombin, Forms an inactive Thrombin complex

hepatin binds to both ATIII and thrombin, Forms an inactive Thrombin complex

Effect of Thrombin innactivation?

Thrombin converts Fibrinogen to Fibrin, 


Stopping this prevents formation of fibrin mesh, making clot less stable

Thrombin converts Fibrinogen to Fibrin,




Stopping this prevents formation of fibrin mesh, making clot less stable

Advantages of Low Molecular Weight Heparin?

LMW Heparin acts faster, and its effects last longer


They can only effect factor Xa, not Thrombin

LMW Heparin acts faster, and its effects last longer




They can only effect factor Xa, not Thrombin