Which mineral is abundantly contained in bones?

MNS 2015

Applied Anatomy

Easy

Appeared in: MNS 2015

Explanation

Calcium is the most abundant mineral in the human body.
Approximately 99% of the body's total calcium is stored in the bones and teeth, making it the most plentiful mineral in skeletal tissue.
It combines with phosphate to form hydroxyapatite crystals, which provide the essential hardness and structural integrity to bones.
Bones also act as a dynamic reservoir for calcium, releasing it into the bloodstream to maintain critical physiological functions when blood levels are low.

Option A: Iron's primary function is oxygen transport in the blood as a component of hemoglobin. It is only found in trace amounts in bone and is not a structural element.
Option C: Sodium is the main cation in the extracellular fluid and is vital for maintaining fluid balance, nerve transmission, and acid-base balance. It is not a significant structural part of bone.
Option D: Although phosphorus is the second most abundant mineral in bone and is essential for forming hydroxyapatite, it is present in smaller quantities than calcium. The typical Ca:P ratio in bone is about 2:1.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Mineral composition of bones as background academic context rather than a clinical decision trigger.
Nurses play a crucial role in educating patients about dietary sources of calcium (e.g., milk, dairy products, leafy greens) and vitamin D to prevent bone diseases like osteoporosis.
Monitoring serum calcium levels is important in clinical practice, as imbalances (hypocalcemia or hypercalcemia) can indicate underlying health issues, including bone disorders, kidney disease, or parathyroid problems.
What if? If a patient has chronic kidney disease, their ability to excrete phosphate is impaired, leading to high phosphate levels. This can cause calcium to be pulled from the bones, leading to renal osteodystrophy, a serious bone disease. The nurse's role includes managing diet and administering phosphate binders.

How to Approach the Question

First, identify the key term in the question: "abundantly". This directs you to find the mineral present in the largest quantity.
Recall the basic composition of bones. You should remember that bones are primarily made of a mineral complex that gives them hardness.
Evaluate the options based on their primary roles in the body.
Eliminate Iron and Sodium, as their main functions are related to blood and fluid balance, respectively, not bone structure.
Between Calcium and Phosphorus, recall that while both are essential for bone formation (as hydroxyapatite), Calcium is the more predominant component. The very name 'calcification' points to calcium's primary role.

Concept Tested & Keywords

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E6 Biochemistry U Satyanarayana— Part 2 (pp 421-820 of 840) pp. 21-23, 41-43

E6 textbook of Applied Biochemistry and Nutrition & DieteticsHarbans Lal (pp 26-464 of 479) p. 297-299