Blood clots form from platelet activation. Platelet activation occurs from a breach in a blood vessel wall that exposes collagen and platelet tissue factor. Platelet tissue factor is a protein that enables cells to initiate blood coagulation cascades, similar to a car pileup, which makes the formation of clots possible.
A blood clot is the final product of the blood coagulation step in homeostasis. Homeostasis is a process which causes bleeding to stop, that is to say that it keeps blood within a damaged blood vessel. A blood clot is also known as a thrombus, and has two components, the first of which is the aggregation of platelets that form a platelet plug and a mesh of cross linked fibrin protein. A blood clot is a healthy response to injury intended to prevent bleeding. Bleeding in this context refers to blood escaping from the circulatory system, or hemorrhaging. In fact homeostasis is the first stage of wound healing whereby blood goes from a liquid to a gel, otherwise known as coagulation.
On a daily basis, blood clots form as a result of impact or injury and dissolve in the blood stream without medical intervention. However, blood clots can be harmful in thrombosis, when clots obstruct blood flow through healthy vessels. A thrombus can decrease blood flow through a vessel, known as a mural thrombus, or block blood flow completely. A thrombus that completely obstructs the flow of blood through a vessel is known as an occlusive thrombus, and can result in the death of tissue supplied by the obstructed vessel. Tissue death in this context is known as an infarct. If a thrombus dislodges from the blood vessel and becomes free-floating it is referred to an embolus .
Visiting your doctor and treating this disease with blood thinners (anticoagulants) is essential to a successful recovery.
In order to fully appreciate the risks associated with blood clots a distinction must be made between blood clots in veins versus blood clots in arteries. Veins carry blood from the body to the heart where it passes on through the lungs and becomes oxygenated. This means that a blood clot in a vein does not usually cause tissue death, rather it causes swelling, discoloration, and pain. Complete occlusion or blockage of a deep vein is called deep vein thrombosis (DVT). The danger of a blood clot in a vein in a scenario such as deep vein thrombosis (DVT) is that a blood clot, usually in the leg, can dislodge. Embolization is the process by which the thrombus breaks free from the vascular wall and becomes mobile. This free-floating clot passes through the heart and becomes lodged in the lungs. When reaching the lungs this clot causes pain and shortness of breath. This life threatening complication is referred to as a Pulmonary Embolism