Final answer:
Yes, calcium is a required co-factor in enzymatic complexes across the entire coagulation cascade, contributing to both the extrinsic and intrinsic pathways as well as the common pathway.
Step-by-step explanation:
Calcium is indeed a required co-factor in the enzymatic complexes of the coagulation cascade. In both the extrinsic pathway and intrinsic pathway, calcium ions (Ca²⁺) play a critical role. As factor IV in the coagulation process, calcium is necessary for the function of various enzymes and complexes. In the extrinsic pathway, Ca²⁺ is essential for the formation of the enzyme complex that leads to the activation of factor X and eventually to the common pathway.
Similarly, in the intrinsic pathway, Ca²⁺ participates in the activation sequence that also culminates in the activation of factor X. Consequently, calcium is integral to the overall coagulation cascade, affecting not just a single pathway, but both intrinsic and extrinsic pathways, as well as the common pathway where fibrin is produced to seal off the vessel.