1. Which of the following is the primary buffer system in the extracellular fluid (ECF)?
Answer: c) Bicarbonate buffer system
Explanation: The bicarbonate buffer system is the most important buffer in the extracellular fluid. It involves the equilibrium between carbonic acid (H₂CO₃) and bicarbonate (HCO₃⁻), which helps maintain pH within a narrow range. This system is crucial for neutralizing excess acids and bases.
2. During metabolic acidosis, which compensatory mechanisms are most likely to occur?
Answer: c) Hyperventilation
Explanation: In metabolic acidosis, there is an excess of acid or a loss of bicarbonate. The body compensates by increasing the respiratory rate (hyperventilation) to expel CO₂, which helps reduce the hydrogen ion concentration and partially correct the acidosis.
3. A patient has a blood pH of 7.50, PCO₂ of 32 mmHg, and HCO₃⁻ of 24 mEq/L. Which of the following is the most likely diagnosis?
Answer: b) Respiratory alkalosis
Explanation: A blood pH of 7.50 indicates alkalosis. The low PCO₂ (32 mmHg) suggests that the alkalosis is due to a respiratory cause, as hyperventilation leads to excessive loss of CO₂, reducing the carbonic acid in the blood.
4. Which of the following conditions is most likely to cause a metabolic alkalosis?
Answer: c) Prolonged vomiting
Explanation: Prolonged vomiting leads to a significant loss of gastric acid (HCl), resulting in a reduction of hydrogen ions in the body and causing metabolic alkalosis. The body compensates by retaining bicarbonate to maintain the acid-base balance.
5. In a case of compensated respiratory acidosis, which of the following laboratory findings is expected?
Answer: a) Normal pH, elevated PCO₂, elevated HCO₃⁻
Explanation: In compensated respiratory acidosis, the kidneys retain bicarbonate to neutralize the excess hydrogen ions due to high PCO₂. This compensatory mechanism normalizes the pH, even though PCO₂ remains elevated.
6. Which of the following is the fastest mechanism for regulating blood pH?
Answer: c) Buffer systems in the blood
Explanation: Buffer systems act immediately to resist changes in pH by neutralizing excess acids or bases. The bicarbonate buffer system is particularly effective in the blood. Respiratory and renal mechanisms act more slowly.
7. An arterial blood gas (ABG) shows pH 7.25, PCO₂ 60 mmHg, and HCO₃⁻ 26 mEq/L. Which of the following is the most likely condition?
Answer: b) Respiratory acidosis without compensation
Explanation: A pH of 7.25 indicates acidosis. The elevated PCO₂ (60 mmHg) suggests a respiratory cause. Since bicarbonate (HCO₃⁻) is within normal limits (26 mEq/L), it indicates that the kidneys have not yet compensated by retaining bicarbonate.
8. What is the primary renal response to respiratory alkalosis?
Answer: c) Increased excretion of bicarbonate
Explanation: In response to respiratory alkalosis, the kidneys excrete more bicarbonate to lower the blood pH toward normal. This helps to counteract the alkalosis caused by a decrease in carbon dioxide levels.
9. Which of the following would most likely lead to a decrease in plasma bicarbonate concentration?
Answer: b) Diarrhea
Explanation: Diarrhea causes the loss of bicarbonate from the intestines, leading to a decrease in plasma bicarbonate concentration, which can result in metabolic acidosis.
10. A patient's ABG results show pH 7.38, PCO₂ 48 mmHg, and HCO₃⁻ 28 mEq/L. What is the most appropriate interpretation of these findings?
Answer: b) Compensated respiratory acidosis
Explanation: The pH of 7.38 is within the normal range but on the lower side, indicating slight acidosis. The elevated PCO₂ (48 mmHg) suggests a respiratory cause, and the elevated HCO₃⁻ (28 mEq/L) indicates that the kidneys have compensated by retaining bicarbonate to normalize the pH.
50 Analytical Multiple Choice Questions on Acid Base Balance with Explanation- Part 1
50 Analytical Multiple Choice Questions on Acid Base Balance with Explanation- Part 2
50 Analytical Multiple Choice Questions on Acid Base Balance with Explanation- Part 3
50 Analytical Multiple Choice Questions on Acid Base Balance with Explanation- Part 4
50 Analytical Multiple Choice Questions on Acid Base Balance with Explanation- Part 5
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