Question

Write a note on the coagulation of blood.

Answer 1

Hint: The process of changing blood from liquid to gel state to save from excessive bleeding and later resulting in a repair mechanism.

Complete answer:
Blood coagulation is also known as blood clotting. It is the process in which blood changes from the liquid state to the semi-solid state, to form a clot to prevent the excessive loss of blood from the broken blood cells. This results in homeostasis, stopping of blood loss, and lastly the repair.

The mechanism of coagulation of blood involves the functioning of platelets. The old coagulation starts as soon as the endothelium of blood vessels is damaged due to an injury. It leads to changes in platelets and the formation of cross-linked fibrin. The platelets act as a plug at the site of injury along with several clotting factors and fibrin to stop the blood flow and form a clot.

The damaged platelets release thromboplastin which starts the formation of a prothrombinase enzyme in the blood. Prothrombinase is a coagulation factor that depends upon the calcium ions. In the presence of calcium ions, the prothrombinase enzyme converts soluble fibrinogen into insoluble fibrin. These fibrin fibers form a mesh or interwoven network of fibers around the blood cell, platelets, and plasma to form the clot which normally takes around 3-8 minutes.

Note: Fibrin is a fibrous, non-globular protein that is involved in the process of blood clotting over an injury. If the fibrin is produced in excess then it may lead to thrombosis, which is the blockage of blood vessels due to the accumulation of platelets, red blood cells, and clotting factors. If the fibrin protein is broken down prematurely then it may lead to a hemorrhage.