What is the correct order of these events?
1. Conversion of fibrinogen to fibrin
2. Clot retraction and leakage of serum
3. Thromboplastin formation
4. Conversion of prothrombia to thrombin

Options

A. 3, 2, 1, 4
B. 3, 4, 1, 2
C. 3, 4, 2, 1
D. 4, 1, 3, 2

Answer

To determine the correct order of the events involved in blood clotting, we need to analyze each step in the clotting cascade:

1. **Thromboplastin Formation**: This is the initial step where injured tissues and platelets release thromboplastin (also known as tissue factor). This is crucial for initiating the clotting process.

2. **Conversion of Prothrombin to Thrombin**: Thromboplastin activates the conversion of prothrombin, a plasma protein, into thrombin, an enzyme that plays a key role in the clotting process.

3. **Conversion of Fibrinogen to Fibrin**: Thrombin then catalyzes the conversion of fibrinogen, a soluble plasma protein, into fibrin, which forms a mesh-like structure that constitutes the bulk of the clot.

4. **Clot Retraction and Leakage of Serum**: Finally, after the clot is formed, it undergoes retraction, which helps to stabilize the clot and reduce the size of the wound. During this process, serum (the liquid part of blood) may leak out.

Putting these steps in order, we have:

1. Thromboplastin formation (Step 3)
2. Conversion of prothrombin to thrombin (Step 4)
3. Conversion of fibrinogen to fibrin (Step 1)
4. Clot retraction and leakage of serum (Step 2)

Thus, the correct order of these events is:
**3 → 4 → 1 → 2**