Part 3: Respiratory Volumes and Capacities (25 MCQs)

Part 3: Respiratory Volumes and Capacities (25 MCQs)

Q1. The volume of air inspired or expired during normal quiet breathing is called:

A. Inspiratory reserve volume
B. Tidal volume
C. Residual volume
D. Expiratory reserve volume

Answer: B

Explanation:

• A. Incorrect: Inspiratory reserve is extra inhalation.
• B. Correct: Tidal volume (≈500 mL) is normal breath volume.
• C. Incorrect: Residual volume remains after maximal exhalation.
• D. Incorrect: Expiratory reserve = extra exhaled air.

Q2. Average tidal volume in a healthy adult is about:

A. 100 mL
B. 300 mL
C. 500 mL
D. 1,000 mL

Answer: C

Explanation:

• A. Incorrect: Too low.
• B. Incorrect: Below normal.
• C. Correct: Normal tidal volume = 500 mL.
• D. Incorrect: Too high.

Q3. Inspiratory reserve volume (IRV) is approximately:

A. 500 mL
B. 1000 mL
C. 2500–3000 mL
D. 4500 mL

Answer: C

Explanation:

• A. Incorrect: 500 mL = tidal volume.
• B. Incorrect: Too low for IRV.
• C. Correct: IRV = 2500–3000 mL extra air inhaled after normal inspiration.
• D. Incorrect: 4500 mL = vital capacity approx.

Q4. Expiratory reserve volume (ERV) is approximately:

A. 500 mL
B. 1000–1100 mL
C. 2500 mL
D. 3000 mL

Answer: B

Explanation:

• A. Incorrect: Too low.
• B. Correct: ERV = 1000–1100 mL extra air exhaled beyond tidal expiration.
• C. Incorrect: Too high.
• D. Incorrect: Value closer to IRV.

Q5. Residual volume (RV) is approximately:

A. 500 mL
B. 1100–1200 mL
C. 2500 mL
D. 3500 mL

Answer: B

Explanation:

• A. Incorrect: 500 mL = tidal volume.
• B. Correct: RV = 1100–1200 mL left after maximal expiration.
• C. Incorrect: Too high.
• D. Incorrect: Not RV.

Q6. Vital capacity (VC) is equal to:

A. TV + IRV
B. IRV + ERV
C. TV + IRV + ERV
D. TV + RV

Answer: C

Explanation:

• A. Incorrect: Excludes ERV.
• B. Incorrect: Excludes TV.
• C. Correct: VC = TV + IRV + ERV (≈4600 mL).
• D. Incorrect: Includes RV, not correct.

Q7. Total lung capacity (TLC) is equal to:

A. VC + RV
B. VC + TV
C. IRV + ERV
D. TV + RV

Answer: A

Explanation:

• A. Correct: TLC = VC + RV (≈5800 mL).
• B. Incorrect: TV already part of VC.
• C. Incorrect: Not complete.
• D. Incorrect: Excludes major volumes.

Q8. Functional residual capacity (FRC) is equal to:

A. TV + RV
B. ERV + RV
C. IRV + ERV
D. TV + ERV

Answer: B

Explanation:

• A. Incorrect: TV is not part of FRC.
• B. Correct: FRC = ERV + RV (≈2200–2300 mL).
• C. Incorrect: Not correct.
• D. Incorrect: TV is excluded.

Q9. Inspiratory capacity (IC) is equal to:

A. TV + IRV
B. ERV + RV
C. TV + ERV
D. IRV + RV

Answer: A

Explanation:

• A. Correct: IC = TV + IRV.
• B. Incorrect: That’s FRC.
• C. Incorrect: Wrong combo.
• D. Incorrect: Not correct.

Q10. Expiratory capacity (EC) is equal to:

A. TV + ERV
B. IRV + ERV
C. TV + RV
D. ERV + RV

Answer: A

Explanation:

• A. Correct: EC = TV + ERV.
• B. Incorrect: Not a defined capacity.
• C. Incorrect: Wrong combo.
• D. Incorrect: That’s part of FRC.

Q11. Which volume cannot be measured by a spirometer?

A. Tidal volume
B. Expiratory reserve volume
C. Inspiratory reserve volume
D. Residual volume

Answer: D

Explanation:

• A. Incorrect: TV measurable.
• B. Incorrect: ERV measurable.
• C. Incorrect: IRV measurable.
• D. Correct: RV cannot be expelled, hence not measurable.

Q12. The normal vital capacity in healthy adults is about:

A. 2000 mL
B. 3500 mL
C. 4500–4800 mL
D. 6000 mL

Answer: C

Explanation:

• A. Incorrect: Too low.
• B. Incorrect: Still below.
• C. Correct: Normal VC ≈ 4500–4800 mL.
• D. Incorrect: Too high (TLC).

Q13. Which lung capacity is the maximum volume of air a person can breathe in after forced expiration?

A. Vital capacity
B. Inspiratory capacity
C. Total lung capacity
D. Functional residual capacity

Answer: C

Explanation:

• A. Incorrect: VC excludes RV.
• B. Incorrect: IC < TLC.
• C. Correct: TLC is maximum volume (≈5800 mL).
• D. Incorrect: FRC is air left after normal expiration.

Q14. Which capacity is reduced most in obstructive lung diseases (like asthma)?

A. Vital capacity
B. Inspiratory reserve volume
C. Expiratory reserve volume
D. Residual volume

Answer: C

Explanation:

• A. Incorrect: VC affected but less.
• B. Incorrect: IRV less affected.
• C. Correct: ERV decreases due to blocked airways.
• D. Incorrect: RV often increases.

Q15. Which capacity is most useful for diagnosing restrictive lung diseases?

A. Total lung capacity
B. Inspiratory capacity
C. Expiratory reserve volume
D. Functional residual capacity

Answer: A

Explanation:

• A. Correct: TLC is reduced in restrictive diseases.
• B. Incorrect: IC less important.
• C. Incorrect: ERV not main diagnostic.
• D. Incorrect: FRC secondary.

Q16. Which lung volume remains in the lungs after maximal expiration?

A. Tidal volume
B. Expiratory reserve volume
C. Residual volume
D. Inspiratory capacity

Answer: C

Explanation:

• A. Incorrect: TV is normal breath.
• B. Incorrect: ERV = extra exhaled air.
• C. Correct: RV remains always.
• D. Incorrect: IC = TV + IRV.

Q17. Minute volume of respiration is:

A. TV × respiratory rate
B. VC × respiratory rate
C. TLC × respiratory rate
D. FRC × respiratory rate

Answer: A

Explanation:

• A. Correct: Minute volume = tidal volume × breaths/min (≈500 × 12 = 6000 mL/min).
• B. Incorrect: VC not used normally.
• C. Incorrect: TLC not used.
• D. Incorrect: FRC is not ventilated each minute.

Q18. Alveolar ventilation is:

A. Total air inspired per minute
B. Air reaching alveoli per minute
C. Total lung capacity
D. Expiratory reserve volume

Answer: B

Explanation:

• A. Incorrect: That’s minute ventilation.
• B. Correct: Alveolar ventilation = (TV – dead space) × rate.
• C. Incorrect: TLC unrelated.
• D. Incorrect: ERV unrelated.

Q19. Anatomical dead space in adults is about:

A. 50 mL
B. 150 mL
C. 500 mL
D. 1000 mL

Answer: B

Explanation:

• A. Incorrect: Too low.
• B. Correct: About 150 mL of air remains in conducting airways.
• C. Incorrect: 500 mL = tidal volume.
• D. Incorrect: Too high.

Q20. Which lung volume is most affected in emphysema?

A. Residual volume increases
B. Tidal volume decreases
C. Inspiratory reserve volume increases
D. Vital capacity increases

Answer: A

Explanation:

• A. Correct: Emphysema traps air, increasing RV.
• B. Incorrect: TV relatively normal.
• C. Incorrect: IRV not increased.
• D. Incorrect: VC decreases, not increases.

Q21. In an adult, the total lung capacity (TLC) is about:

A. 2000 mL
B. 3500 mL
C. 5800 mL
D. 7000 mL

Answer: C

Explanation:

• A. Incorrect: Too low.
• B. Incorrect: Still low.
• C. Correct: TLC ≈ 5800 mL in adults.
• D. Incorrect: Too high.

Q22. Which capacity decreases in pregnancy due to elevated diaphragm?

A. Inspiratory capacity
B. Functional residual capacity
C. Tidal volume
D. Vital capacity

Answer: B

Explanation:

• A. Incorrect: IC not much affected.
• B. Correct: FRC decreases due to upward diaphragm.
• C. Incorrect: TV may increase.
• D. Incorrect: VC remains fairly constant.

Q23. Which term refers to the volume of air exchanged per breath at rest?

A. Minute volume
B. Residual volume
C. Tidal volume
D. Vital capacity

Answer: C

Explanation:

• A. Incorrect: Minute volume = per minute.
• B. Incorrect: Residual = left over.
• C. Correct: TV = ~500 mL per breath.
• D. Incorrect: VC = maximal exchange.

Q24. Which factor increases tidal volume?

A. Sleep
B. Exercise
C. Anesthesia
D. High altitude

Answer: B

Explanation:

• A. Incorrect: Sleep reduces ventilation.
• B. Correct: Exercise increases TV and rate.
• C. Incorrect: Anesthesia depresses breathing.
• D. Incorrect: High altitude increases rate but not always TV.

Q25. Which lung volume is useful to predict successful extubation in ventilated patients?

A. Residual volume
B. Tidal volume
C. Vital capacity
D. Functional residual capacity

Answer: C

Explanation:

• A. Incorrect: RV not measurable.
• B. Incorrect: TV not sufficient.
• C. Correct: VC indicates patient’s ability to breathe deeply.
• D. Incorrect: FRC not routinely used.

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