Which of the following is not a clotting factor?

AIIMS Bhopal NO - 2018 (Shift-1st)

Applied Physiology

Easy

Appeared in: AIIMS Bhopal NO - 2018 (Shift-1st)

Explanation

Sodium is an essential electrolyte in the body but does not participate in the enzymatic cascade of blood coagulation.
The primary physiological roles of sodium include maintaining the body's fluid balance, regulating blood pressure, and supporting nerve and muscle function.
The coagulation process relies on a specific set of proteins (factors) and cofactors like calcium, but sodium ions are not directly involved.

Option A: Prothrombin is a crucial clotting factor (Factor II). It is a precursor protein (zymogen) that is converted into the active enzyme thrombin during the clotting process.
Option C: Fibrinogen is Clotting Factor I. It is a soluble plasma protein that is converted by thrombin into insoluble fibrin strands, which form the meshwork of a blood clot.
Option D: Calcium is Clotting Factor IV. Calcium ions are essential cofactors required at several steps of the coagulation cascade, facilitating the binding of clotting factors to phospholipid surfaces.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Identification of substances involved in the blood coagulation cascade as background academic context rather than a clinical decision trigger.
Understanding the clotting cascade is vital for nurses to safely administer anticoagulant medications (e.g., warfarin, heparin) and to correctly interpret coagulation lab results (PT, aPTT, INR).
Knowledge of clotting factors is essential for managing patients with bleeding disorders like hemophilia (deficiency of Factor VIII or IX) or conditions like Disseminated Intravascular Coagulation (DIC).
What if? If a patient has severe liver disease, the synthesis of many clotting factors (like Prothrombin and Fibrinogen) is impaired. This would lead to a prolonged prothrombin time (PT) and a significantly increased risk of severe bleeding.

How to Approach the Question

First, identify the negative framing of the question with the word "not". This means you are looking for the option that is an exception.
Next, review the options provided and consider the primary function of each substance in the body.
Recall the key components of the blood coagulation cascade. Prothrombin, Fibrinogen, and Calcium are well-known participants.
Identify Sodium as a major electrolyte primarily involved in fluid balance and nerve conduction, not blood clotting.
Conclude that Sodium is the correct answer because it does not fit the category of a clotting factor.

Concept Tested & Keywords

Concept Tested: Identification of substances involved in the blood coagulation cascade.
Stem keywords: clotting factor
Lead-in keywords: not
Negative lead-in flag: The question asks to identify the substance that is NOT a clotting factor.

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