20 Multiple Choice Questions on Acid-Base Regulation

Here are 20 multiple choice questions with answers covering acid-base regulation as discussed in Guyton Physiology.

Basic Concepts of Acid-Base Balance

Which of the following best defines acidosis? A) pH < 7.35 B) pH > 7.45 C) A condition that promotes acidemia D) A condition that promotes alkalemia
Answer: C) A condition that promotes acidemia 1
What is the normal range of arterial pH in humans? A) 7.0-7.2 B) 7.2-7.3 C) 7.35-7.45 D) 7.5-7.6
Answer: C) 7.35-7.45 1
Which of the following represents the normal range of PaCO₂ in arterial blood? A) 20-30 mmHg B) 34-46 mmHg C) 50-60 mmHg D) 60-70 mmHg
Answer: B) 34-46 mmHg 1

Which buffer system provides the most immediate buffering capacity for acid-base disturbances? A) Bicarbonate buffer system B) Phosphate buffer system C) Protein buffer system D) Hemoglobin buffer system
Answer: A) Bicarbonate buffer system 2
In the bicarbonate buffer system, what is the primary equation that describes the relationship? A) H₂O + CO₂ ⟶ H₂CO₃ ⟶ H⁺ + HCO₃⁻ B) H⁺ + HPO₄²⁻ ⟶ H₂PO₄⁻ C) H⁺ + Protein⁻ ⟶ HProtein D) NH₃ + H⁺ ⟶ NH₄⁺
Answer: A) H₂O + CO₂ ⟶ H₂CO₃ ⟶ H⁺ + HCO₃⁻ 1

Which organ is primarily responsible for regulating the respiratory component of acid-base balance? A) Kidneys B) Liver C) Lungs D) Pancreas
Answer: C) Lungs 3
How do the lungs compensate for metabolic acidosis? A) By decreasing ventilation B) By increasing ventilation C) By increasing bicarbonate production D) By decreasing bicarbonate excretion
Answer: B) By increasing ventilation 4
What is the effect of hypoventilation on acid-base balance? A) Respiratory alkalosis B) Respiratory acidosis C) Metabolic alkalosis D) Metabolic acidosis
Answer: B) Respiratory acidosis 1

Which organ is primarily responsible for regulating the metabolic component of acid-base balance? A) Lungs B) Liver C) Kidneys D) Brain
Answer: C) Kidneys 2
What is the primary mechanism by which the kidneys compensate for respiratory acidosis? A) Increased hydrogen ion excretion B) Decreased bicarbonate reabsorption C) Increased bicarbonate reabsorption and generation D) Decreased ammonia production
Answer: C) Increased bicarbonate reabsorption and generation 2
What is the minimum serum bicarbonate level that should be maintained in patients with chronic kidney disease to prevent metabolic acidosis? A) 18 mmol/L B) 20 mmol/L C) 22 mmol/L D) 24 mmol/L
Answer: C) 22 mmol/L 1

Which of the following is characteristic of compensated respiratory acidosis? A) High PaCO₂, normal pH, low HCO₃⁻ B) High PaCO₂, normal pH, high HCO₃⁻ C) Low PaCO₂, normal pH, low HCO₃⁻ D) Low PaCO₂, normal pH, high HCO₃⁻
Answer: B) High PaCO₂, normal pH, high HCO₃⁻ 1
What is the definition of type 2 respiratory failure? A) PaO₂ < 60 mmHg with normal PaCO₂ B) PaO₂ < 60 mmHg with elevated PaCO₂ C) Elevated PaCO₂ regardless of PaO₂ D) Low PaO₂ with low PaCO₂
Answer: C) Elevated PaCO₂ regardless of PaO₂ 1
Which acid-base disorder would you expect in a patient with severe diarrhea? A) Metabolic acidosis B) Metabolic alkalosis C) Respiratory acidosis D) Respiratory alkalosis
Answer: A) Metabolic acidosis 1

Which parameter is used to indicate the contribution of the metabolic component to acid-base status? A) PaCO₂ B) Base excess C) Anion gap D) Both B and C
Answer: D) Both B and C 1
What does the term 'STPD' refer to in gas measurements? A) Standard temperature and pressure, dry B) Standard temperature and pressure, damp C) Standard time and pressure, dry D) Standard time and pressure, damp
Answer: A) Standard temperature and pressure, dry 1
What is the dead space to tidal volume ratio (VD/VT) an index of? A) Oxygen exchange efficiency B) Carbon dioxide exchange efficiency C) Nitrogen balance D) Acid production
Answer: B) Carbon dioxide exchange efficiency 1

What is the effect of acidosis on potassium balance? A) Hypokalemia due to increased renal excretion B) Hyperkalemia due to shift of K⁺ from intracellular to extracellular fluid C) No effect on potassium levels D) Hypokalemia due to shift of K⁺ from extracellular to intracellular fluid
Answer: B) Hyperkalemia due to shift of K⁺ from intracellular to extracellular fluid 5
Which of the following is a consequence of chronic metabolic acidosis? A) Increased protein synthesis B) Decreased bone resorption C) Increased protein degradation D) Increased plasma branched chain amino acids
Answer: C) Increased protein degradation 1
What is the primary sensor mechanism for detecting changes in extracellular pH? A) Direct proton sensing by specialized receptors B) Bicarbonate sensing by soluble adenylyl cyclase C) Carbonic anhydrase activity D) Hemoglobin oxygen saturation
Answer: B) Bicarbonate sensing by soluble adenylyl cyclase 6