Topics:
Animal Nutrition, Animal Refresher
Major Ions of Extracellular Fluid
The major cation & anion of extracellular fluid (ECF) are respectively:
- $Na^{+}$, $Cl^{-}$ — Correct Answer
- $K^{+}$, $PO_{4}^{-}$
- $Na^{+}$, $PO_{4}^{-}$
- None
Explanation:
Correct Answer: Na⁺, Cl⁻
The major cation of Extracellular Fluid (ECF) is Na⁺ (Sodium) and the major anion is Cl⁻ (Chloride). ECF includes blood plasma, interstitial fluid, and lymph.
Fluid Compartment Electrolytes
| Fluid | Major Cation | Major Anion |
|---|---|---|
| Extracellular Fluid (ECF) | Na⁺ | Cl⁻ |
| Intracellular Fluid (ICF) | K⁺ | PO₄³⁻ |
Mineral Excretion Routes
- Na⁺ and K⁺ → excreted mainly via urine
- Ca and P → excreted mainly via faeces
- Exception: In carnivores, P is excreted mainly via urine
Clinical Relevance
- Hyponatraemia (low Na⁺ in ECF) → weakness, confusion, oedema
- Normal blood Na⁺ in cattle: ~135–150 mEq/L
- Na⁺ is the primary osmotic force maintaining ECF volume
Why Other Options Are Wrong
- K⁺, PO₄³⁻ → major cation and anion of ICF, not ECF
- Na⁺, PO₄³⁻ → Na⁺ is correct (ECF cation) but PO₄³⁻ is the ICF anion, not ECF anion
- None → incorrect; Na⁺ and Cl⁻ are well-established ECF electrolytes
📚 About this Topic — Animal Nutrition
This multiple choice question is from Animal Nutrition, Animal Refresher. It has 4 options with a detailed explanation of the correct answer. Practice more MCQs from Animal Nutrition to strengthen your preparation.
