Blood clotting factors: Prothrombin, essential for coagulation, is released/produced by which organ? Consider the site of plasma protein synthesis and vitamin K–dependent factors. Choose the correct organ.

Difficulty: Easy

Liver
Platelets
Bone marrow
Kidney

Correct Answer: Liver

Explanation:

Given data

Asked: source of prothrombin.

Concept / Approach
Liver synthesizes most plasma proteins, including prothrombin (Factor II), a vitamin K–dependent clotting factor.

Clarification
Platelets provide platelet factors but do not synthesize prothrombin; bone marrow makes blood cells, not this plasma protein.

Final Answer
Liver.

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