A schematic of the clotting cascade is:
Also note where VIIIa and Va are involved.
Now look at the same schematic again but with the addition of activated protein C and antithrombin:
So as well as learning the cascade itself make sure the following are etched in your brain:
- activated protein C inhitbits VIIIa and Va
- antithrombin inhibits Xa and IIa
- protein C is converted to activated protein C by protein S and finally
- factors II, VII, IX, X are vitamin-K dependent (method of remembering: '1972')
With all that groundwork covered, lets move on to battle 14.3 and put a bit of it into practice.