Blood Clotting Cascade Process — NEET Biology
✅ Asked in NEET 2022You know that when you cut your finger or hurt yourself, your wound does not continue to bleed for a long time; usually the blood stops flowing after sometime. Do you know why? Blood exhibits coagulation or clotting in response to an injury or trauma. This is a mechanism to prevent excessive loss of blood from the body. You would have observed a dark reddish brown scum formed at the site of a cut or an injury over a period of time. This clot is formed mainly of a network of threads called fibrin in which dead and damaged formed elements of blood are trapped. Fibrins are formed by the conversion of inactive fibrinogen in the plasma by the enzyme thrombin. Thrombins, in turn, are formed from another inactive substance present in the plasma called prothrombin. An enzyme complex, thrombokinase, is required for the above reaction. This complex is formed by a series of linked enzymatic reactions (cascade process) called the mechanism of blood coagulation. An injury or a trauma stimulates the platelets in the blood to release certain factors which activate the mechanism of coagulation. Certain factors released by the tissues at the site of injury also can initiate coagulation. Calcium ions play a very important role in clotting.
NTA tests whether students understand that fibrin (not thrombin) forms the network threads in a blood clot. Thrombin is an enzyme that converts fibrinogen into fibrin, so students often confuse which component actually structures the clot. The cascade involves prothrombin → thrombin (via thrombokinase enzyme), then fibrinogen → fibrin. Remember: fibrin is the structural protein creating the physical clot network; thrombin is the enzyme catalyst. Calcium ions and platelet factors are essential cofactors. This distinction appears repeatedly in NEET exams because it tests deep understanding of the coagulation mechanism sequence.
This paragraph was tested 2 times in NEET.
Given below are two statements: [NEET 2022 Phase 1] Statement I: The coagulum is formed of network of threads called thrombins. Statement II: Spleen is the graveyard of erythrocytes.
Which enzyme is responsible for the conversion of inactive fibrinogens to fibrins? (NEET 2021)
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