Electrolytes and Body Fluids—Identify the Correct Statement(s) Which statement about sodium and chloride in human physiology is accurate?

Introduction / Context:
Sodium (Na+) and chloride (Cl−) are the dominant electrolytes of the extracellular fluid (ECF). Their concentrations strongly influence osmolarity, fluid distribution, acid–base balance, and gastric physiology. This question checks recognition of their principal roles and locations.

Given Data / Assumptions:

• Normal physiology without pathological states (e.g., hypo/hypernatremia).
• Focus on ECF composition, osmotic regulation, and gastric secretion.

Concept / Approach:
In the ECF, Na+ is the main cation and Cl− the main anion. Together with bicarbonate, they determine ECF osmolarity and volume. Chloride is secreted by gastric parietal cells along with hydrogen ions to form hydrochloric acid (HCl), essential for digestion and innate defense. Therefore, each individual statement is correct, making “All of these” the best choice.

Step-by-Step Solution:

Verification / Alternative check:
Clinical practice relies on serum sodium/chloride to assess ECF status; hypochloremia can impair gastric acid secretion.

Why Other Options Are Wrong:

• Any single-statement choice is incomplete because all three statements are correct.

Common Pitfalls:
Confusing intracellular (K+, phosphate) with extracellular (Na+, Cl−) predominance; overlooking chloride’s role in gastric physiology.

Final Answer:
All of these