What starts the extrinsic pathway of blood clotting?

Question

What starts the extrinsic pathway of blood clotting?

Answer 1

The tissue factor pathway (we don't say extrinsic pathway really any more in biology) is started by trauma to tissue. This is the primary way that a blot clot is started in the body. The goal is to get a large amount of Thrombin in the blood. Thrombin will lead to fibrin, which traps cells to form a clot.

The pathway is, as said, started by injury to a blood vessel, releasing Tissue Factor. Essentially, Factor VII is converted to VIIa, which activates X, which goes on to activate prothrombin.

Wiki does a good job of explaining. I'll include the link.