Bones consist of?

DHS Staff Nurse - 2018 (Shift-2nd)

Applied Anatomy

Medium

Appeared in: DHS Staff Nurse - 2018 (Shift-2nd)

Explanation

This option is correct because none of the given pairs accurately describe the primary structural components of bone.
Bone tissue is a composite material, made primarily of an inorganic mineral component and an organic matrix.
The inorganic component, which provides hardness, is mainly composed of calcium and phosphate in the form of hydroxyapatite crystals.
The organic matrix, which provides flexibility, is about 90% Type I collagen.
Therefore, the combination of 'Calcium and iron' is incorrect, as are the other unrelated options.

Option A: Bile is a digestive fluid produced by the liver, and insulin is a hormone that regulates blood sugar. Neither has a structural role in bone.
Option B: Urine and feces are metabolic waste products that are excreted from the body. They are not components of any tissue.
Option C: While calcium is the most abundant mineral in bone, iron is not a primary structural component of the bone matrix. Iron's main role is in oxygen transport via hemoglobin.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Composition of Bone Tissue as background academic context rather than a clinical decision trigger.
Understanding bone composition is fundamental for nurses in managing patients with metabolic bone diseases like osteoporosis, osteomalacia, and rickets.
Nurses play a key role in educating patients about the importance of adequate dietary intake of calcium and Vitamin D for maintaining bone health and preventing fractures.
What if a patient has chronic kidney disease? Their kidneys fail to convert vitamin D to its active form and excrete phosphate, leading to low blood calcium and high phosphate. This disrupts bone metabolism, causing a condition called renal osteodystrophy.

How to Approach the Question

This is a factual recall question that tests your knowledge of basic anatomy and physiology.
First, analyze the question: 'Bones consist of?'. This asks for the primary building blocks of bone tissue.
Next, evaluate each option. Eliminate choices that are clearly incorrect based on general biological knowledge. 'Bile and insulin' (digestion/metabolism) and 'Urine and feces' (waste products) are unrelated to bone structure.
Critically assess the most plausible-looking option: 'Calcium and iron'. Recall that calcium is indeed the main mineral in bones. However, think about the role of iron. Iron is essential for blood, not for the bone's structural matrix.
Recall that the primary mineral combination in bone is calcium and phosphate (forming hydroxyapatite).
Since none of the provided options list the correct combination (Calcium and Phosphate) or the full picture (Collagen, Calcium, Phosphate), the 'None of these' option is the most accurate choice.

Concept Tested & Keywords

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E6 Nelson Textbook of Pediatrics(2024) — Volume 2 p. 2187-2189

E6 Medicine Harrison 22e Part 2 p. 1165-1167