Conversion of Prothrombin to thrombin requires
In the presence of tissue phospholipids (PL) and calcium ions, activated Factor X (Xa) combines with Factor Va to form prothrombin activator which initiates the conversion of prothrombin to thrombin.Factor V, X, and XII are activated and involved in other steps of intrinsic pathway.Ref: Ganong&;s review of medical physiology, 23rd edition, page: 533
Ca++
Va, Ca++
V, X, Ca++
X, V, XII, & Ca++
Cardiovascular system