The figure below shows the mechanism of blood clotting.
![](http://spmbiology.blog.onlinetuition.com.my/wp-content/uploads/sites/20/2014/02/blood-clotting-3.png)
- When a blood vessel is damaged, platelets will gather around the wound and coagulate.
- At the same time, an enzyme called thrombokinase will be released.
- Thrombokinase will convert the inactive prothrombin to the active thrombin.
- The thrombin will then catalyses the soluble fibrinogen to the insoluble fibrin.
- Fibrin will form a fibrous network to trap the blood cells and form the blood clot.