Step I Coagulation cascade clarification...

[CBG23]

So, I am relearning the coagulation cascade and am confused about which steps require calcium and or phospholipids to take place. I am looking in my copy of Robbins and the diagram shows only two steps that require both phospolipids and calcium, while a few others just require calcium. However, first aid shows a bunch more as requiring both phopholipids and calcium. My old class notes don't correspond to either...I was wondering what the generally accepted set of phospholipid and/or calcium containing reactions were or if it's even important to know this...

 

[knuckles]

Well doesn't vitamin K gamma carboxylation add calcium binding spots onto the coag factors, so you could probably assume that 2,7,9,10, c and s, require calcium. I think this is incredibly low yield though.

 

[IMGUSMLEStep1]

yea, I really don't think you would ever get a question this specific on the USMLE.

 

[aa62]

from what I remember, Ca2+ + PPLs are required for the activation of the Xase (intrinsic - factor IXa + VIIIa; extrinsic - factor VIIa + factor III) and thrombinase (factor Xa + Va) complexes.

doubt you would ever get a question about the specific cofactors.