Which one of the following ions helps in blood clotting?

RRB Staff Nurse Kolkata-2015

Applied Physiology

Easy

Appeared in: RRB Staff Nurse Kolkata-2015

Explanation

Calcium ions (Ca²⁺) are designated as Factor IV in the blood coagulation cascade.
Ca²⁺ acts as an essential cofactor for the activation and function of several clotting factors, including prothrombin (Factor II), Factor VII, Factor IX, and Factor X.
It facilitates the binding of these factors to phospholipid surfaces, which is a critical step for the conversion of prothrombin to thrombin and the subsequent formation of a fibrin clot.
The entire process of blood clotting is dependent on the presence of adequate calcium ions in the blood.

Option B: Manganese (Mn²⁺) is a cofactor for many enzymes in the body, but it does not play a primary or direct role in the main sequence of reactions in the blood clotting cascade.
Option C: Potassium (K⁺) is the primary intracellular cation and is vital for nerve impulse transmission, muscle contraction (especially cardiac muscle), and maintaining fluid and electrolyte balance. It has no direct function in blood clotting.
Option D: Phosphate (PO₄²⁻) is a key component of bones and teeth, nucleic acids (DNA and RNA), and high-energy compounds like ATP. It also acts as an important intracellular buffer. It is not involved in the coagulation cascade.

Visual 1: Flowchart - A diagram of the coagulation cascade (intrinsic, extrinsic, and common pathways), highlighting the multiple steps where Calcium (Ca²⁺) is required as a cofactor.
Visual 2: Diagram - An illustration showing how Ca²⁺ ions act as a bridge to link clotting factors to the phospholipid membrane of a platelet.

Clinical Relevance

Nursing practice connection: Knowing Role of ions in blood coagulation helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
A key nursing and laboratory practice is the use of anticoagulants in blood collection tubes. Tubes with lavender (EDTA), light blue (sodium citrate), or gray (potassium oxalate) tops prevent clotting by chelating (binding) calcium ions, making them unavailable for the coagulation cascade.
Patients with severe hypocalcemia (low blood calcium) may have impaired blood clotting, leading to an increased risk of bleeding. Nurses should monitor for signs of bleeding, such as petechiae, ecchymosis, or prolonged bleeding from puncture sites.
What if the question asked about a vitamin essential for clotting? The answer would be Vitamin K, which is required by the liver to synthesize several clotting factors (II, VII, IX, X). While Vitamin K is needed for production, Ca²⁺ is the ion needed for the activation and function of these factors in the bloodstream.

How to Approach the Question

This is a factual recall question from physiology.
First, identify the core concept in the question: 'ion' and 'blood clotting'.
Access your knowledge of the coagulation cascade. Recall the names and numbers of the clotting factors.
Remember that one of the factors is not a protein but an ion. Identify this specific ion.
Evaluate the given options. Ca²⁺ is known as Factor IV and is a well-known component of the cascade. The other ions (Mn²⁺, K⁺, PO₄²⁻) have other primary physiological roles not directly related to clotting.
Select Ca²⁺ as the correct answer based on this direct recall.

Concept Tested & Keywords

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