Question

In human, the prothrombin required for blood clotting is produced in
(a)Liver
(b)Stomach
(c)Pancreas
(d)Spleen

Answer 1

Hint: Prothrombin is a coagulation factor or clotting factor that is required for the normal clotting of blood. The final clot formation occurs after a cascade of events and the formation of a meshwork of fibrin strands with cellular elements. Prothrombin is produced in the largest gland of the human body.

Complete answer:
Prothrombin is a precursor to the thrombin which forms the final clot. This prothrombin is secreted in the Liver. It is the coagulation factor II which is the precursor of thrombin. This thrombin acts as a protease to convert the soluble fibrinogen into insoluble strands of fibrin which intermesh with cellular elements to complete the clot formation.

Additional Information: -Prothrombin was discovered in 1894 by Pekelharing.
-This prothrombin when acted upon by activated factor X is converted to thrombin.
 -This activation of prothrombin is essential for both physiological and pathological coagulation.
A few rare diseases that involve the prothrombin include hypoprothrombinemia, the presence of antiprothrombin antibodies, etc.
-Prothrombin complex concentrate is a rich coagulation factor preparation that is often used to correct deficiencies of prothrombin. This is also used in case of prolonged intractable bleeding caused due to warfarin.
So, the correct answer is, “Liver”

Note: -The production of prothrombin in the liver is a Vitamin K-dependent reaction that converts 10-12 glutamic acid molecules to gamma-carboxyglutamic acid. Hence, the deficiency of vitamin K or administration of warfarin which is an anticoagulant inhibits this process, thus slowing the activation of the coagulation cascade.
-Prothrombin time(PT) and its derived measures called international normalized ratio (INR) and prothrombin ratio(PR), are a set of assays used to evaluate the pathways of coagulation.