When there's a wound, the blood vessels are damaged. To stop the loss of blood, the clotting cascade starts off and forms a clot. This clot is a thrombus, right? Seems like perfect physiology. Where does the clot occur? As in, if we consider the vessel to be a pipe, the clot is formed at one end to block the flow or is attached to the wall of the vessel on one side?

This doubt arises because thrombosis (considered pathological) is defined as a clot within a blood vessel. Is the same not happening when there is an injury? If we consider the clot formed at one side of the vessel wall, doesn't it become thrombosis? Even if the clot is like a plug, it has to be attached to the wall, right?

In short, what is the difference between a clot due to a wound and one thrombosis (due to the Virchow's triad)? Where are the clots attached in either cases?

  • $\begingroup$ Thrombosis is formation of clots without injury due to reasons like ineffectiveness of heparin. Yes, clots are formed on the side of blood vessel, so they prevent blood leakage, not blood flow. $\endgroup$ Mar 4, 2016 at 4:52

1 Answer 1


Here are a couple of distinctions,

1) The thrombus is the actual blood clot

2) Thrombosis is the condition of having a clot form in the blood vessel.

3) If the thrombus breaks away and becomes capable of traveling to some distant site, we refer to that as an embolus.

4) If the embolus lodges somewhere disrupting blood flow, we call that embolism, or in the case of a thrombus, thromboembolism.

So referring here, a protein called tissue factor is expressed on the outside of blood vessels, and when ruptured, is exposed to the blood stream that carries Factor VII. This initiates the coagulation response, and through the action of these factors you get platelets sticking to the endothelium, thrombin cleaving fibrinogen to fibrin that sticks to the platelets, and the fibrin/platelet plug forming over the wound is like a gel and RBCs become mired in it. So really, the thrombus is stuck to the endothelial wall.

  • $\begingroup$ so thrombosis is a thrombus occurring without an injury? $\endgroup$
    – Polisetty
    Mar 4, 2016 at 13:50
  • 1
    $\begingroup$ With or without, there are blood pathologies that can cause clotting without significant injury, such as A-fib, which is particularly dangerous because those thrombus tend to embolise. $\endgroup$
    – CKM
    Mar 4, 2016 at 14:49

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