Question

Which sequence is correct for the following events?

1. fibrinogen → fibrin
2. clot retraction
3. formation of thromboplastin
4. prothrombin → thrombin

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

Answer 1

The correct sequence is 3, 4, 1, 2 - formation of thromboplastin, prothrombin to thrombin, fibrinogen to fibrin, clot retraction, which corresponds to option A in the question about the sequence of events in blood clotting. The correct option is A).

Step-by-step explanation:

The correct sequence for the events involved in blood clotting is as follows:

1. Formation of thromboplastin - This step involves the activation of the intrinsic or extrinsic pathways, which then lead to the common pathway.
2. Prothrombin → thrombin - Once factor X has been activated, the enzyme thromboplastin (prothrombinase) converts prothrombin into the active enzyme thrombin.
3. Conversion of fibrinogen to fibrin - Thrombin then converts fibrinogen (factor I) into insoluble fibrin protein strands, which form the mesh of the clot.
4. Clot retraction - This final step involves the tightening of the fibrin clot by contractile proteins within the platelets, pulling the edges of the clot together and squeezing out serum.

Therefore, the correct sequence of events is 3, 4, 1, 2, which corresponds to option A.