Metabolic alkalosis occurs when:
(a) Bicarbonate ion concentrations become elevated
(b) A severe bicarbonate loss occurs
(c) The kidneys fail to excrete hydrogen ions
(d) Ketone bodies are generated in abnormally large quantities

Verified step by step guidance

1. Step 1: Understand the definition of metabolic alkalosis. It is a condition where the pH of body fluids is elevated above normal due to an increase in bicarbonate (HCO3-) concentration or a loss of hydrogen ions (H+).
2. Step 2: Analyze option (a): 'Bicarbonate ion concentrations become elevated.' Since bicarbonate is a base, an increase in its concentration would raise the pH, leading to alkalosis. This aligns with the definition of metabolic alkalosis.
3. Step 3: Analyze option (b): 'A severe bicarbonate loss occurs.' Losing bicarbonate would reduce the base concentration, which would lower pH and cause acidosis, not alkalosis.
4. Step 4: Analyze option (c): 'The kidneys fail to excrete hydrogen ions.' Retaining hydrogen ions would increase acidity, causing acidosis rather than alkalosis.
5. Step 5: Analyze option (d): 'Ketone bodies are generated in abnormally large quantities.' Ketone bodies are acidic, so their accumulation leads to metabolic acidosis, not alkalosis.

Key Concepts

Metabolic Alkalosis

Metabolic alkalosis is a condition characterized by an elevated blood pH due to increased bicarbonate concentration or loss of hydrogen ions. It results in the blood becoming more alkaline, often caused by factors like excessive vomiting or diuretic use.

Bicarbonate Ion Role in Acid-Base Balance

Bicarbonate ions (HCO3-) act as a primary buffer in the blood, neutralizing acids to maintain pH balance. An increase in bicarbonate concentration raises blood pH, leading to alkalosis, while a decrease can cause acidosis.

Kidney Function in Acid-Base Regulation

The kidneys regulate acid-base balance by excreting hydrogen ions and reabsorbing bicarbonate. Failure to excrete hydrogen ions can cause acidosis, while excessive bicarbonate retention or hydrogen ion loss can lead to alkalosis.