Question

The component of blood which prevents its coagulation in the blood vessels is:
A. Hemoglobin
B. Plasma
C. Thrombin
D. Heparin

Answer 1

Hint: It is synthetically produced as an anticoagulant. Heparin is considered as the natural anticoagulant of the body which prevents blood clotting in blood vessels by preventing the formation of thrombin. It is also synthetically produced.

Complete answer:It is a glycosaminoglycan (GAG).
GAGs are heteropolysaccharides (having many monomer sugars molecules that are different, more than one) with uronic acids.
Heparin binds to the enzyme inhibitor antithrombin III (ATIII). This causes a conformational change that results in its activation through an increase in the flexibility of its reactive site of the enzyme. The activated AT inactivates thrombin, factor Xa (Stuart–Prower factor), and other proteases.
Thrombin is the active form of prothrombin (activated by intrinsic and extrinsic coagulation pathways). It is a serine protease.

Additional information: Functions of thrombin include the following:
1. Conversion of fibrinogen to fibrin (active form).
2. Activation of clotting factors V, VIII, XI, and XIII.
3. Heparin can also be injected into muscles or blood vessels to prevent/ lyse up blood clots. Thus, it acts as a blood thinner.
4. Used in many extracorporeal therapies such as kidney dialysis, in the treatment of coagulation disorders such as deep vein thrombosis (DVT), and to passivate (use of a light coat of a protective material) the surfaces of indwelling devices, such as catheters, etc.

So the correct answer is option 4: Heparin

Note: As anticoagulants are warfarin and aspirin, they're given to people at a high risk of getting clots (congenital abnormalities and defects) to reduce their chances of developing serious conditions such as strokes and heart attacks.