Which of the following is the most factor that can increase the volume of air entering the lung?

Correct Answer: A

Rationale: Air enters the lungs during inspiration per Boyle's law: thoracic expansion lowers intrapulmonary pressure below atmospheric (e.g., 760 to 758 mmHg), creating a pressure gradient driving airflow. Increasing this gradient via stronger diaphragm and intercostal contraction directly boosts inspired volume (e.g., from 500 ml to 600 ml), the primary factor. Increase in action potential' likely means neural impulses to respiratory muscles; more impulses enhance contraction, but this is secondary to the gradient they produce. Combining both overcomplicates pressure is the direct mechanism. Decreasing the gradient reduces flow, opposing the goal. The pressure gradient is the key driver, quantifiable (e.g., 1-2 mmHg for tidal breathing), linking muscle action to volume via physics, distinguishing it as the most impactful factor in ventilation mechanics.

Correct Answer: D

Rationale: Pneumothorax introduces air into the pleural space, negating intrapleural pressure (~-4 mmHg), collapsing the lung via elastic recoil and expanding the chest wall outward via its recoil increasing thoracic diameter, true. Venous return drops as positive pleural pressure (e.g., tension pneumothorax) compresses vena cava, reducing preload true. Vital capacity (VC) falls as collapsed lung limits exhalable volume (e.g., from 4-5 L) true. Lung compliance (C = ΔV / ΔP) doesn't increase collapsed lung tissue isn't more stretchable; compliance is a lung property unaffected by deflation, effectively zero in collapse, not raised. The false notion of increased compliance misrepresents pneumothorax, where pressure loss, not elasticity, drives effects, making it the untrue statement amid accurate mechanical outcomes.

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.