A
thrombus, or colloquially a
blood clot, is the final product of the
blood coagulation step in
hemostasis. There are two components to a thrombus: aggregated
platelets that form a platelet plug, and a mesh of cross-linked
fibrin protein. The substance making up a thrombus is sometimes called
cruor. A thrombus is a healthy response to
injury intended to prevent bleeding, but can be harmful in
thrombosis, when clots obstruct blood flow through healthy blood vessels.