Let’s talk about the Coagulation Cascade involved in Secondary Hemostasis. Basically, there are three interrelated pathways of coagulation, each representing a unique series of biochemical reactions. These pathways are the Intrinsic, Extrinsic, and the common pathway. Each pathway is activated by a different mechanism. The activation of the Intrinsic pathway occurs when a blood vessel is injured, exposing the subendothelial basement membrane and collagen. Both surfaces promote coagulation.