Question

One of the most abundant extracellular ions that represents about 90% is

• A. Chloride
• B. Sodium
• C. Calcium
• D. Potassium

Answer 1

The correct option is B Sodium

Sodium (Na+) is the most abundant extracellular ion, represents about 90% of extracellular cations. It is involved in impulse transmission, muscle contraction, and fluid and electrolyte balance. Sodium (Na+) creates most of the osmotic pressure of extracellular fluid (ECF) and is the most abundant cation in ECF. It is essential for the electrical activity of neurons and muscle cells. The primary mechanism regulating sodium concentration is aldosterone, which stimulates the distal tubule of the nephron unit to reabsorb sodium. Imbalances cause hypo or hypernatremia.

• Hyponatremia is a consequence of excessive sweating, diarrhea, or vomiting causing dizziness, confusion, weakness, low BP, and shock.
• Hypernatremia is a consequence of excessive water loss or sodium ingestion, causing a loss of ICF characterized by extreme thirst and agitation. So, the correct answer is option B.