We have the extrinsic pathway and we have the intrinsic pathway. So let's begin by focusing briefly on the extrinsic pathway. So in the extrinsic pathway, what happens is, once we have the cut in the endothelium of the blood vessel, that exposes an important interior glycoprotein that wasn't there before. And this is known as TF, which stands for tissue factor. Now, everything shown in this diagram that is purple, that basically describes a protein that is not an enzyme. And so the tissue factor is not an actual enzyme.