Clotting of blood involves which one among the following clotting proteins?

Blood clotting, or coagulation, is a complex physiological process essential for maintaining hemostasis and preventing hemorrhage. Fibrinogen is a critical soluble plasma protein that serves as the precursor to fibrin. During the final stage of the coagulation cascade, thrombin (a serine protease) cleaves fibrinogen into insoluble fibrin subunits [5]. These subunits polymerize to form a stable fibrin mesh that traps platelets and blood cells, effectively plugging leaks in the circulatory system [5]. While platelets initiate the primary hemostatic plug, fibrinogen is indispensable for secondary hemostasis and the stabilization of the clot [5]. In contrast, pathogens are disease-causing microorganisms [4], while macrophages and phagocytes are specialized immune cells involved in the innate immune response and the engulfment of foreign materials rather than the structural formation of blood clots [4].

Sources

1. [5] https://www.nature.com/articles/s41392-023-01452-1
2. [1] https://www.ncbi.nlm.nih.gov/books/NBK482253/
3. [4] https://www.ncbi.nlm.nih.gov/books/NBK459455/
4. [2] Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > Maintenance by platelets > p. 94
5. [3] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 3: Health: The Ultimate Treasure > 3.4.1 How are communicable diseases caused and spread? > p. 32