It's the extracellular matrix outside the blood vessel. And this is the inside portion, the lumen of our blood vessel. Now, the first thing we should notice about our blood clotting cascade is all these proteins involved within this cascade are found inside the blood plasma. So they are circulating inside that blood plasma. And anytime we have a rupture that takes place. Because these are found inside the blood plasma, they are ready to be activated and they are ready to basically form those blood clots.