Interactive Quiz: Acid-Base Balance

What is the normal range of arterial blood pH?

• 6.8 – 7.2

• 7.0 – 7.4

• 7.35 – 7.45

• 7.5 – 7.8

Answer explanation

The normal range of arterial blood pH is 7.35 – 7.45. This range is crucial for proper physiological function, as values outside this range can indicate acidosis or alkalosis.

Bicarbonate is the most important extracellular buffer.

• True

• False

Answer explanation

True. Bicarbonate acts as a crucial extracellular buffer by maintaining pH balance in the blood, neutralizing excess acids, and playing a key role in the body's acid-base homeostasis.

If HCO₃⁻ = 24 mEq/L and pCO₂ = 40 mmHg, what is the pH using H–H equation?

• 7.2

• 7.3

• 7.4

• 7.5

Answer explanation

Using the Henderson-Hasselbalch equation: pH = 6.1 + log(HCO₃⁻/0.03*pCO₂). Substituting HCO₃⁻ = 24 mEq/L and pCO₂ = 40 mmHg gives pH ≈ 7.4, making 7.4 the correct answer.

Which enzyme catalyzes the conversion of H₂CO₃ into CO₂ and H₂O at the apical membrane?

• Na⁺/H⁺ exchanger

• H⁺ ATPase

• Carbonic anhydrase

• Aldosterone

Answer explanation

Carbonic anhydrase is the enzyme that catalyzes the conversion of carbonic acid (H₂CO₃) into carbon dioxide (CO₂) and water (H₂O) at the apical membrane, facilitating gas exchange in tissues.

What is the formula used to calculate the anion gap in clinical practice?

• Na⁺ + Cl⁻ – HCO₃⁻

• Na⁺ – (Cl⁻ + HCO₃⁻)

• (Na⁺ + K⁺) – (Cl⁻ + HCO₃⁻)

• Cl⁻ – (Na⁺ + HCO₃⁻)

Answer explanation

The correct formula for calculating the anion gap is Na⁺ – (Cl⁻ + HCO₃⁻). This formula helps assess metabolic acidosis by measuring the difference between positively and negatively charged ions in the blood.

What is the normal range of the serum anion gap?

• 4–8 mEq/L

• 6–10 mEq/L

• 8–16 mEq/L

• 12–22 mEq/L

Answer explanation

The normal range of the serum anion gap is 8–16 mEq/L. This range is important for assessing metabolic acidosis and electrolyte imbalances, making it the correct choice among the options provided.

A raised anion gap always indicates lactic acidosis.

• True

• False

Answer explanation

A raised anion gap can indicate various conditions, not just lactic acidosis. Other causes include ketoacidosis and renal failure. Therefore, the statement is false.