In our article on blood coagulation, we will get to know deeply about the meaning of coagulation of blood, the mechanism behind coagulation of blood and its major factors. It will help you develop a general basic understanding of the whole process of coagulation of blood. This article is a comprehensive section in blood coagulation zoology notes.

What is the coagulation of blood?

What happens when we get injured, and blood starts flowing from our bruises? How does the flow of blood stop on its own? The answer to this question is the coagulation of blood. Coagulation of blood is a process through which blood clots are formed. It is done by the body mainly to stop the excessive loss of blood at the site of injury. Blood coagulation is a secondary function; the blood clots formed are known as secondary hemostasis. The primary role is played by calcium in the clotting of blood. If not for this process, the bruises will not stop bleeding, and injury can not be treated.

The significant factors for plasma clotting are –

As we have learned what coagulation of blood is. We now need to know what will coagulate blood? Some factors that influence this clotting of blood are  –

Important notes *

• There is no factor VI. 
• Vitamin K is essential for factors II, VII and  X.

Mechanism for blood coagulation

There is a very complex procedure through which the coagulation of blood happens. Let us know in detail about every step followed for this complex procedure and its reason. What will coagulate blood, and in how many steps?

• The trauma stimulates our body to produce blood coagulating elements whenever we get injured. Thromboplastins are the major substances that start the process of blood coagulation. Tissues at the place of injury also start producing tissue thromboplastins.
• After the formation of thromboplastins, it leads to the production of a new enzyme complex called thrombokinase. Thrombokinase is formed by a linked process known as the cascade process. It involves several factors present in plasma in the inactive state. 
• Thrombokinase now converts the inactive protein present in plasma prothrombin to thrombin.
• The newly formed enzyme changes soluble fibrinogen of plasma into insoluble fibrin. The body should have ample calcium ions for thrombin to perform efficiently. 
• Fibrin forms a network of threads that trap dead and damaged blood cells to form clots, otherwise known as coagulum.
• The clots or extra tissues are formed at the site of injury. This whole process is how blood coagulation works. The clots formed are like platelets plug, preventing the blood from coming out.

The chemical equation behind coagulation of blood

To understand the mechanism more efficiently, we will now take the help of chemical equations.

What is Haemostasis?

The whole process leading to the coagulation of blood is called haemostasis. It includes the whole physiological process, right from the arrest of bleeding from the damaged blood vessels to the blood clotting. It has three important stages – 

1. Vasoconstriction – in this process, the platelets attach themselves to the damaged injury site and release serotonin. This process further reduces the blood flow to the injured area. Certain chemicals such as thromboxanes are released by the damaged vessels themselves.
2. Platelets plug formation – The attached platelets join together and form a clump and release another new substance called adenosine diphosphate (ADP). This process helps attract more platelets to the injury site by the damaged vessel itself. This process is known as a positive feedback system. 
3. Coagulation – During this process, a final clot is formed over the injured site. This is the final process that marks the completion of a whole complex process.

What is Fibrinolysis?

We have studied the clotting of blood and the formation of platelet plugs, but what happens when the healing process is complete.

After the healing process is complete, another process called fibrinolysis occurs. Fibrinolysis is the process of breaking down blood clots after the repairing process is done. During this process, plasminogen, which is trapped within the clots, changes into an enzyme called plasmin. Then this new product, plasmin, breaks fibrin into waste material, which is later removed by phagocytosis. After this, the healing process is complete, and the integrity of the blood vessel wall is restored. This whole process can be seen as the opposite of the blood coagulation process and completes the journey from injury to healing.

Conclusion

In this section of blood coagulation zoology notes, we have covered the basics of coagulation of blood. We have tried to explain the steps that are being followed by the body for clotting of blood. The factors involved are also discussed in brief. Significant after-effects of blood coagulation like fibrinolysis are explained in this article. Here, we learned in detail the process and about what will coagulate blood.