Ventilation (breathing) is a regular, rhythmic process which:

Correct Answer: A

Rationale: Ventilation moves air into and out of the lungs (A) . This mechanical process, driven by inspiratory muscles (diaphragm, intercostals), shifts 500 mL tidal volume 12-15 times/minute (Page 4), per Boyle's law thoracic expansion drops pressure, drawing air in; relaxation expels it. Energy release (B) is cellular respiration, not ventilation. Surface tension reduction (C) is surfactant's role, not breathing's. Mucus clearance (D) involves cilia, not ventilation itself. A's focus on airflow diaphragm drops 1-2 cm, expanding thorax 5-7 cm distinguishes it from B's metabolic or C's chemical roles, aligning with respiratory physiology (Page 2, ventilation definition).

Correct Answer: D

Rationale: Residual volume (RV) stays constant lifelong (D) (Page 4, Ans: D). RV (~1.2 L) is air left after maximal expiration, not tidal (A, false tidal ends at FRC, ~2.5 L). COPD increases RV (B, false) via air trapping (hyperinflation, TLC > 6 L). Fibrosis reduces RV (C, false) by stiffening lungs (TLC < 6 L, Q1). D's stability set by lung structure, not age holds unless disease alters elasticity or recoil (normal 20-25% TLC). Unlike A's confusion with FRC or B's obstructive error, D reflects physiology's baseline, per spirometry standards.

Correct Answer: D

Rationale: Intrapleural pressure is always less than atmospheric (D) . At rest (FRC), it's -5 cm H2O (755 mmHg vs. 760 mmHg); inspiration drops it to -7 cm H2O, aiding lung expansion. A's only inspiration' is false it's always negative. B's equality occurs in pneumothorax (Q11). C's definition fits transpulmonary pressure, not intrapleural alone. D's consistency unlike A's limit maintains lung inflation, per pleural mechanics (Q60).

Correct Answer: C

Rationale: Surfactant isn't deficient in term neonates . Type II cells mature by 36 weeks, producing surfactant (Q26). It causes hysteresis (A, true), easing inspiration vs. expiration. It doesn't raise resistance (B, false) it lowers work (Q9). Edema prevention (D) is indirect via stability, not primary. C's term-neonate claim unlike A's lung behavior contradicts physiology; deficiency is preterm (IRDS, Q5).

Correct Answer: D

Rationale: In pulmonary fibrosis, FEV1/FVC is ≥ normal. A 10% diameter increase cuts resistance (R ∝ 1/r^4), not raises it (A, false). COPD is common (B, false). Fibrosis restricts, not obstructs (C, false resistance normal). D's ratio (> 80%) holds as FEV1 and FVC drop evenly (Q1), unlike A's physics error, per restrictive physiology.