Which of the following values is above normal in-patient suffering from severe respiratory muscle weakness?

Correct Answer: B

Rationale: Severe respiratory muscle weakness (e.g., in myasthenia gravis) impairs ventilation by weakening inspiratory and expiratory muscles. Tidal volume (VT, ~500 ml normally) decreases due to limited inspiratory force, reducing breath size. Vital capacity (VC, ~4-5 L) drops as maximal inhalation and exhalation are compromised. Oxyhemoglobin saturation falls (e.g., from 95-100% to <90%) as hypoventilation lowers PaO2, causing hypoxemia. Arterial pH may decrease (acidosis) if CO2 retention raises PCO2, but this isn't specified as above normal. However, PCO2 itself (normal 35-45 mmHg) rises above normal (e.g., 50-60 mmHg) due to inadequate CO2 expulsion, a direct result of weak ventilation. Though not listed, if B intended PCO2 (a common mix-up), it fits; otherwise, none are above normal' assuming intent, PCO2's rise is the key abnormality, reflecting ventilatory failure's impact on gas exchange.

Correct Answer: C

Rationale: Surfactant reduces alveolar surface tension, causing hysteresis different inflation vs. deflation pressures in lung P-V curves due to tension dynamics, a true property. It lowers pulmonary resistance by easing expansion, not increasing it false but not queried. Surfactant deficiency is common in preterm neonates (<37 weeks), causing RDS, but in term neonates (≥37 weeks), production is typically mature, making commonly deficient in term-neonates' incorrect RDS is rare at term barring defects. Surfactant indirectly prevents pulmonary edema by stabilizing alveoli, reducing fluid transudation pressure, though not its primary role true enough. The term-neonate error misaligns with developmental physiology, where surfactant sufficiency is expected, distinguishing it as the incorrect statement amid surfactant's established functions.

Correct Answer: D

Rationale: Per Poiseuille's law (R ∝ 1/r^4), a 10% airway diameter increase reduces resistance by ~40%, not increases it false. COPD (e.g., emphysema) is common due to smoking, not least false. Pulmonary fibrosis, restrictive, reduces compliance, not airway resistance (obstructive) false. In fibrosis, FEV1/FVC is ≥80% (normal or higher) as both FEV1 and FVC drop proportionally true, unlike obstructive diseases (<70%). This ratio's preservation reflects restricted volume, not airflow, a key diagnostic feature, making it the true statement amid misconceptions about resistance and prevalence.

Correct Answer: C

Rationale: Coastal regions have milder climates due to water's high specific heat capacity (~4.18 J/g°C) and greater evaporation, moderating temperatures. Evaporation and cloud cover increase humidity, reflecting solar radiation and stabilizing heat summers cool, winters warm compared to inland. Water's albedo (~0.06) is low, absorbing more heat, not reflecting it false. Water's specific heat is higher, not lower, than land (~1 J/g°C), storing energy false. Latitude affects insolation broadly, not coast-specific false. Evaporation and clouds, tied to water's thermal inertia, buffer temperature swings, a key maritime effect (e.g., Mediterranean climates), making this the best explanation.

Correct Answer: B

Rationale: A bronchopulmonary segment is a functional lung unit supplied by a segmental (tertiary) bronchus (A), segmental pulmonary artery (E, implied), nerves (C), and lymphatics (D), all within its connective tissue boundaries. The segmental bronchus delivers air, the artery supplies blood, and nerves and lymphatics manage innervation and drainage. However, pulmonary veins (B) are not segment-specific; they run intersegmentally, collecting blood from multiple segments into larger lobar veins, not confined within a single segment's borders. This venous drainage pattern ensures efficient oxygenation return but excludes B from being a defining component of the segment's structure, unlike the artery and bronchus, which are segmentally discrete. Thus, B is the exception.