Component that causes coagulation if introduced to the blood stream

Full Answer Section

• c) Heparin: This is an anticoagulant, meaning it inhibits coagulation. It works by activating antithrombin, which then inactivates several clotting factors, including thrombin and factor Xa.

In summary, thromboplastin is the component that triggers the coagulation cascade when it comes into contact with blood, typically due to tissue damage.

Sample Answer

The correct answer is d) Thromboplastin. Here's why:

• Thromboplastin (also known as tissue factor or factor III): This is a protein present in subendothelial tissue, platelets, and leukocytes. When blood vessels are damaged, thromboplastin is released and comes into contact with blood. This initiates the extrinsic pathway of the coagulation cascade, leading to the formation of a blood clot.

Let's look at why the other options are not the primary initiators of coagulation when introduced into the bloodstream:

• a) Fibrinogen: This is a soluble plasma protein that is converted into insoluble fibrin by the action of thrombin during the coagulation cascade. While essential for clot formation, it doesn't initiate coagulation on its own.

• b) Prothrombin: This is an inactive precursor protein (zymogen) found in plasma. It is converted into the active enzyme thrombin by prothrombinase (factor Xa with factor Va) during the coagulation cascade. Like fibrinogen, it's crucial for the process but doesn't initiate it.