Assuming a normal anatomic dead space of 150 ml and a fixed respiratory minute ventilation of 6 L/min. Which combination of respiratory rate and tidal volume will give the largest alveolar ventilation?

Correct Answer: D

Rationale: Minute ventilation (VE) = tidal volume (VT) × respiratory rate (RR), fixed at 6 L/min (6000 ml/min). Alveolar ventilation (VA) = (VT - VD) × RR, with anatomic dead space (VD) = 150 ml. For 200 ml at 30/min: VE = 200 × 30 = 6000 ml/min, VA = (200 - 150) × 30 = 50 × 30 = 1500 ml/min. For 300 ml at 20/min: VA = (300 - 150) × 20 = 150 × 20 = 3000 ml/min. For 400 ml at 15/min: VA = (400 - 150) × 15 = 250 × 15 = 3750 ml/min. For 600 ml at 10/min: VA = (600 - 150) × 10 = 450 × 10 = 4500 ml/min. The 600 ml at 10/min maximizes VA (4.5 L/min), as larger VT exceeds VD more, despite lower RR. High RR with low VT wastes ventilation in dead space, reducing VA efficiency. This deeper, slower pattern optimizes gas exchange, making it the best choice.

Correct Answer: A

Rationale: Functional residual capacity (FRC) = expiratory reserve volume (ERV) + residual volume (RV). RV = 1.0 L via helium dilution. The spirogram shows vital capacity (VC = IRV + VT + ERV) from max inhalation to max exhalation. Without the figure, assume typical female values: VC ~4 L, TLC ~5 L. FRC is post-normal expiration; if ERV (exhalable beyond tidal) is ~1 L (common for young women), FRC = ERV + RV = 1 + 1 = 2.0 L. Higher FRC (2.5-3.5 L) fits larger frames or males (~3 L). The 2.0 L aligns with RV and minimal ERV, plausible for a 22-year-old female, reflecting resting volume per standard physiology.

Correct Answer: B

Rationale: The Coriolis effect is an apparent deflection of moving objects (e.g., air, water) due to Earth's rotation, not a true force but an inertial effect in a rotating frame. In the Northern Hemisphere, it deflects right; Southern, left proportional to velocity and latitude (2ωv sinφ). Gravity drives weight, not deflection false. Pressure gradients from solar heating drive winds, not Coriolis false. Friction (e.g., surface drag) opposes motion, not deflects false. Coriolis shapes weather patterns (e.g., cyclones), per geophysical fluid dynamics (e.g., Holton), making it the best description, distinct from physical forces or heating effects.

Correct Answer: C

Rationale: Thyroidectomy risks nerve injury near thyroid arteries. The internal laryngeal nerve (A, B) pierces the thyrohyoid membrane, unrelated to vocal cords (sensory above). The recurrent laryngeal nerve (D) innervates all intrinsic laryngeal muscles except cricothyroid, looping near the inferior thyroid artery, but C the external laryngeal nerve (branch of superior laryngeal) with the superior thyroid artery is key. It supplies the cricothyroid, which tenses vocal cords. Ligation here slackens the cord (weak voice), unlike D's paralysis (hoarseness, midline cord). C fits the symptoms.

Correct Answer: C

Rationale: A needle at the 9th intercostal space, midaxillary, below the lung's lower border (C), affects pleura (D), diaphragm (A), or spleen (B), but not the lung. C is correct.