Fibrinolysis Prevents Thrombus Formation

The balance between coagulation and anticoagulation allows us to stay alive as human beings and fibrinolysis actively participates in this balance. We'll tell you more about it in this article.
Fibrinolysis Prevents Thrombus Formation

Last update: 27 May, 2021

Fibrinolysis is a natural process in the human body that’s responsible for breaking down the networks formed by a molecule called fibrin. These networks are what eventually form thrombus or blood clots. Hence, fibrinolysis prevents the formation of clots and prevents the development of certain conditions such as ischemia.

There are two types of fibrinolysis depending on whether the process is natural or pathological:

  • Primary, this is the natural breakdown of blood clots due to all the biological mechanisms involved.
  • The secondary is the breakdown of clots due to a health disorder, medication, or other extraneous cause. The result of this type of fibrinolysis is usually heavy bleeding.

What’s a thrombus and how does it form?

A thrombus is a blood clot that doesn’t dissolve and remains within the blood vessel in which it formed. This thrombus, or part of it, can break away from the vessel and travel through the bloodstream. People refer to it as an embolus when this occurs.

In this way, clots are plugs that form in the blood vessels. Thus, these vessels clog and the blood can longer circulate properly to irrigate the organs and surrounding tissues involved.

Furthermore, it’s important to know about the process of coagulation in order to understand fibrinolysis. This is because one could say it’s like the reverse process. In this respect, blood circulates without coagulation and there’s a balance in the processes of coagulation and anticoagulation when a person is healthy.

In the event of damage to a vessel, the injury triggers a chain reaction that leads to the formation of a clot in order to prevent continued bleeding. Different molecules such as thrombin and fibrin come into play here.

Coagulation causes the fibrin molecule to transform into fibrinogen to form a kind of stable mesh. This way, the blood cells accumulate in this network to seal the vascular damage and prevent continued bleeding.

A woman trying to stop nose bleeding.
The body sets in motion coagulation mechanisms to stop it when we have a nosebleed, for example.

What’s fibrinolysis?

As we mentioned above, fibrinolysis is the opposite process to the one explained above. It actually prevents the formation of clots, especially in situations where these shouldn’t form.

The fibrinolytic enzyme system is complementary to the coagulation system, and functions as a mechanism that balances the formation, deposition, and elimination of fibrin. This is to stop uncontrolled coagulation in the vascular and extravascular systems.

Plasmin is the fundamental enzyme of the fibrinolytic system, and the degradation of fibrin by this enzyme forms the basis of fibrinolysis and thrombolysis. Plasmin is normally found in an inactive form. We refer to it as plasminogen when it’s in this state. In turn, this plasminogen can be there in two phases:

  • Free in plasma. Activation and conversion to plasmin happen slowly when in this state.
  • Associated with fibrin. Here, plasminogen is more selectively activated by the action of another molecule, the tissue plasminogen activator.
An illustration about fibrinolysis.
Our body can control the formation of life-threatening clots thanks to fibrinolysis.

Tissue plasminogen activator is a specific protein of blood vessel tissue cells with a high affinity for fibrin. There’s also another pathway for the activation of fibrinolysis, although of lesser intensity, and that’s through a urokinase-type plasminogen activator.

Many drugs can activate the fibrinolytic system and generate significant amounts of plasmin in order to dissolve the thrombus and restore vascular permeability.

The balance of coagulation

Normal hemostasis consists of a balance between procoagulant actions, which cause the production of fibrin by the coagulation pathways, and anticoagulant actions. The anticoagulant actions happen through fibrinolysis which in turn destroys fibrin. It’s this balance that allows us to remain alive.

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