During blood clotting , fibrin is produced by

Options

A. Thrombokinase
B. Prothrombin
C. Liver
D. Proteolysis

Answer

**Step-by-Step Solution:**

1. **Understanding Blood Clotting Process**: Blood clotting, also known as coagulation, is a complex process that prevents excessive bleeding when a blood vessel is injured.

2. **Role of Prothrombin**: When an injury occurs, a protein called prothrombin is released into the bloodstream. Prothrombin is a precursor to thrombin, which is crucial for the clotting process.

3. **Conversion of Prothrombin to Thrombin**: Prothrombin is converted into thrombin in the presence of a prothrombin activator and calcium ions. This is a key step in the clotting cascade.

4. **Thrombin's Function**: Thrombin then acts on another protein called fibrinogen (often misspelled as fibrinozene in the transcript) to convert it into fibrin monomers.

5. **Formation of Fibrin**: The fibrin monomers then polymerize to form fibrin fibers, which are essential for the structural framework of the blood clot. These fibrin fibers crosslink to stabilize the clot.

6. **Conclusion**: Therefore, during blood clotting, fibrin is produced as a result of the action of thrombin on fibrinogen, which is derived from prothrombin.

**Final Answer**: Fibrin is produced by prothrombin (Option 2).

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