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Question 1. Which of the following best describes the effect of decreased lung compliance as seen in pulmonary fibrosis? A) Increased tidal volume for a given pressure B) Decreased work of breathing C) Higher inspiratory pressures required to achieve normal tidal volume D) Reduced airway resistance Answer: C Explanation: Fibrosis stiffens the lung parenchyma, lowering compliance; therefore greater negative intrathoracic pressure (or higher ventilator pressure) is needed to generate a normal tidal volume, increasing work of breathing. Question 2. According to Poiseuille’s law, which factor most directly increases airway resistance in bronchoconstriction? A) Decrease in airway length B) Increase in airway radius C) Decrease in airway radius D) Increase in airflow velocity Answer: C Explanation: Airway resistance is inversely proportional to the fourth power of the radius; a small reduction in radius dramatically raises resistance. Question 3. Surfactant deficiency primarily leads to which of the following physiological changes? A) Increased alveolar surface tension and collapse (atelectasis) B) Decreased diffusion capacity for CO₂ C) Increased pulmonary artery pressure D) Reduced airway smooth-muscle tone
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Answer: A Explanation: Surfactant reduces surface tension; without it, alveoli collapse, especially at low lung volumes, causing atelectasis. Question 4. The primary muscle of inspiration is the: A) External intercostal muscle B) Diaphragm C) Scalenes D) Sternocleidomastoid Answer: B Explanation: The diaphragm contracts, creating negative intrathoracic pressure and drawing air into the lungs; it is the main inspiratory muscle. Question 5. According to Fick’s law, which alteration most reduces the diffusion of O₂ across the alveolar-capillary membrane? A) Increased partial pressure gradient B) Increased membrane thickness C) Increased surface area D) Increased diffusion coefficient Answer: B Explanation: Diffusion is inversely proportional to membrane thickness; diseases that thicken the barrier (e.g., fibrosis) impair O₂ diffusion. Question 6. A patient with a large pulmonary embolus will most likely demonstrate which V/Q pattern? A) High V/Q (dead space) B) Low V/Q (shunt) C) Normal V/Q throughout D) Mixed low and high V/Q in equal proportion
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C) Conversion to bicarbonate via carbonic anhydrase D) Binding to plasma proteins Answer: C Explanation: ~70% of CO₂ is converted to HCO₃⁻ in red cells through carbonic anhydrase, the dominant transport form. Question 10. The sensation of dyspnea is most closely related to: A) Elevated arterial PO₂ B) Increased work of breathing and chemoreceptor stimulation C) Decreased lung compliance alone D) Hyperventilation without hypoxia Answer: B Explanation: Dyspnea arises from a mismatch between respiratory drive (chemoreceptor input) and the mechanical ability to meet that drive, leading to perceived effort. Question 11. A productive cough is primarily generated by stimulation of which structure? A) Upper airway mechanoreceptors only B) Pulmonary stretch receptors C) C-fibers in the tracheobronchial tree responding to irritants D) Chemoreceptors in the carotid body Answer: C Explanation: Irritant receptors (C-fibers) in the airway mucosa trigger the cough reflex, resulting in productive cough when mucus is present. Question 12. Central cyanosis occurs when arterial oxygen saturation falls below approximately:
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A) 95%
B) 90%
C) 85%
D) 80%
Answer: C Explanation: When SaO₂ drops below ~85%, the increased deoxyhemoglobin imparts a bluish hue to mucous membranes, producing central cyanosis. Question 13. Clubbing of the digits is most strongly associated with which underlying pathophysiologic process? A) Chronic hypoxemia leading to vascular proliferation in the nail bed B) Acute airway obstruction C) Hypercapnia without hypoxia D) Elevated serum calcium Answer: A Explanation: Chronic hypoxemia stimulates growth factor release and vascular remodeling in distal digits, producing clubbing. Question 14. Cheyne-Stokes respiration is characterized by: A) Rapid, shallow breaths with irregular periods of apnea B) Gradual crescendo-decrescendo tidal volumes followed by apnea C) Deep, labored breaths with a prolonged expiratory phase D) Irregular breathing with clusters of breaths separated by equal pauses Answer: B Explanation: Cheyne-Stokes shows cyclic hyperventilation (increasing amplitude) followed by a period of apnea, often due to delayed CO₂ response in heart failure or stroke.
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Question 18. An arterial blood gas shows pH 7.30, PaCO₂ 55 mmHg, HCO₃⁻ 28 mEq/L. The primary disturbance is: A) Metabolic acidosis with respiratory compensation B) Respiratory acidosis with metabolic compensation C) Mixed metabolic and respiratory acidosis D) Respiratory alkalosis Answer: B Explanation: Elevated PaCO₂ with a slightly elevated HCO₃⁻ indicates primary respiratory acidosis with renal compensation. Question 19. On chest X-ray, “ground-glass opacities” most commonly indicate: A) Pulmonary edema with alveolar fluid B) Interstitial thickening without complete alveolar filling C) Hyperinflated lungs of emphysema D) Pleural effusion Answer: B Explanation: Ground-glass appearance reflects partial displacement of air by fluid, cells, or fibrosis, typical of early interstitial disease. Question 20. The “air-trapping” phenomenon seen on expiratory CT is most characteristic of: A) Pulmonary fibrosis B) Asthma or COPD (obstructive disease) C) Pulmonary embolism D) Pneumothorax Answer: B Explanation: Obstructive diseases cause incomplete emptying of air during expiration, visible as retained low-attenuation areas on expiratory imaging.
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Question 21. In asthma, the early-phase bronchoconstriction is mediated primarily by: A) Leukotriene B₄ B) Histamine and leukotriene C₄/D₄/E₄ from mast cells C) T-cell cytokines D) Neutrophil elastase Answer: B Explanation: IgE-mediated mast-cell degranulation releases histamine and cysteinyl leukotrienes causing rapid bronchoconstriction. Question 22. Which of the following best describes airway remodeling in chronic asthma? A) Reversible bronchospasm only B) Fixed airway narrowing due to subepithelial fibrosis, smooth-muscle hypertrophy, and mucus gland hyperplasia C) Purely inflammatory infiltrate that resolves with steroids D) Acute edema without structural change Answer: B Explanation: Chronic inflammation leads to structural changes (remodeling) that cause persistent airflow limitation. Question 23. The “blue bloater” phenotype of COPD is most associated with: A) Predominant emphysema and weight loss B) Chronic bronchitis with significant hypoxemia and hypercapnia C) Purely restrictive physiology D) Isolated pulmonary hypertension Answer: B
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Explanation: CFTR mutation hampers chloride transport, causing dehydrated, viscous secretions that obstruct airways. Question 27. According to the “vicious cycle” hypothesis of bronchiectasis, the initial event is: A) Genetic deficiency of surfactant protein B B) Persistent infection leading to chronic inflammation and airway wall damage C) Autoimmune vasculitis of pulmonary vessels D) Acute aspiration of gastric contents Answer: B Explanation: Recurrent infection induces inflammation, which damages bronchial cartilage and epithelium, perpetuating further infection. Question 28. In idiopathic pulmonary fibrosis, the hallmark histologic pattern is: A) Diffuse alveolar damage with hyaline membranes B) Usual interstitial pneumonia (temporal heterogeneity, fibroblastic foci) C) Non-caseating granulomas D) Pulmonary alveolar proteinosis Answer: B Explanation: IPF shows a pattern of usual interstitial pneumonia with patchy fibrosis, fibroblastic foci, and temporal heterogeneity. Question 29. Sarcoidosis most characteristically produces which type of granuloma? A) Caseating granuloma with central necrosis B) Non-caseating epithelioid granuloma without necrosis C) Suppurative granuloma with pus D) Granuloma containing amyloid
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Answer: B Explanation: Sarcoidosis is defined by non-caseating granulomas composed of epithelioid cells and multinucleated giant cells. Question 30. Silicosis predisposes patients to which opportunistic infection? A) Histoplasma capsulatum B) Mycobacterium tuberculosis C) Candida albicans D) Pneumocystis jirovecii Answer: B Explanation: Silica impairs macrophage function, increasing susceptibility to TB. Question 31. Kyphoscoliosis leads to restrictive lung disease primarily because: A) It increases airway resistance B) It reduces thoracic cavity volume, limiting lung expansion C) It destroys alveolar capillary membranes D) It causes chronic bronchial inflammation Answer: B Explanation: Spinal curvature compresses the chest wall, decreasing vital capacity and total lung capacity. Question 32. In myasthenia gravis, respiratory failure is most often due to: A) Diaphragmatic weakness from impaired acetylcholine transmission at the neuromuscular junction B) Central hypoventilation syndrome C) Pulmonary embolism secondary to immobility D) Bronchospasm
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Answer: B Explanation: WHO Group 2 PH results from elevated left-atrial pressure transmitted backward to pulmonary circulation. Question 36. The principal Starling force responsible for cardiogenic pulmonary edema is: A) Increased capillary hydrostatic pressure B) Decreased plasma oncotic pressure C) Increased capillary permeability D) Decreased lymphatic drainage Answer: A Explanation: Elevated left atrial pressure raises pulmonary capillary hydrostatic pressure, forcing fluid into interstitium and alveoli. Question 37. Non-cardiogenic pulmonary edema (e.g., ARDS) is primarily caused by: A) Increased alveolar surfactant production B) Increased alveolar-capillary membrane permeability due to inflammatory injury C) Decreased pulmonary arterial pressure D) Hyperventilation Answer: B Explanation: In ARDS, cytokine-mediated injury disrupts the endothelial-epithelial barrier, allowing protein-rich fluid to leak into alveoli. Question 38. Type I respiratory failure is defined by: A) PaO₂ < 60 mmHg with normal/low PaCO₂ B) PaCO₂ > 50 mmHg with normal PaO₂ C) Both PaO₂ and PaCO₂ elevated
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D) Normal ABG values with increased work of breathing Answer: A Explanation: Type I failure is hypoxemic with inadequate oxygenation despite adequate ventilation. Question 39. During the exudative phase of ARDS, the alveolar spaces are filled primarily with: A) Serous fluid low in protein B) Protein-rich edema, fibrin, and neutrophils C) Pure air with collapsed alveoli D) Blood clots Answer: B Explanation: Increased permeability leads to protein-rich fluid, fibrin deposition, and inflammatory cells, forming hyaline membranes. Question 40. Community-acquired pneumonia typically presents with which radiographic pattern in the lobar form? A) Diffuse interstitial infiltrates B) Consolidation confined to one lobe with air bronchograms C) Bilateral ground-glass opacities D) Pleural effusion only Answer: B Explanation: Lobar pneumonia shows dense consolidation of an entire lobe, often with visible air bronchograms. Question 41. The classic “red hepatization” stage of lobar pneumonia is caused by: A) Alveolar edema only
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Question 44. Small-cell lung carcinoma (SCLC) most commonly produces which paraneoplastic syndrome? A Hypercalcemia due to PTHrP B Hypertrophic osteoarthropathy C SIADH (syndrome of inappropriate antidiuretic hormone secretion) D Ectopic ACTH production Answer: C Explanation: SCLC frequently secretes ADH, leading to euvolemic hyponatremia (SIADH). Question 45. In non-small-cell lung carcinoma, the most frequent histologic subtype is: A) Small-cell carcinoma B) Adenocarcinoma C) Large-cell carcinoma D) Squamous cell carcinoma Answer: B Explanation: Adenocarcinoma now represents the most common NSCLC subtype, especially in nonsmokers.
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Question 46. A tension pneumothorax differs from a simple pneumothorax because it: A) Is always bilateral B) Causes mediastinal shift and hemodynamic compromise due to positive pressure in the pleural space C) Resolves spontaneously without intervention D) Is associated with pleural effusion Answer: B Explanation: Air trapped under pressure pushes mediastinum, compresses vena cava, leading to obstructive shock. Question 47. Light’s criteria are used to differentiate exudative from transudative pleural effusions. Which of the following meets exudate criteria? A) Pleural fluid protein/serum protein ratio < 0.5, LDH ratio < 0.6, pleural LDH < 2/ upper limit of normal B) Pleural fluid protein/serum protein ratio > 0. C) Pleural fluid glucose > 70 mg/dL D) Pleural fluid pH > 7. Answer: B Explanation: An exudate meets at least one Light’s criterion; a protein ratio >0. indicates increased capillary permeability. Question 48. Which of the following best describes the pathophysiology of “air-space” (alveolar) hemorrhage? A) Increased pulmonary capillary hydrostatic pressure alone B) Direct injury to alveolar capillary basement membrane causing blood to enter alveoli C) Obstruction of bronchial arteries D) Lymphatic obstruction
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C) Tuberculosis D) Pulmonary embolism Answer: B Explanation: CHF often produces bilateral, transudative effusions that may be clinically silent. Question 52. Which of the following best explains the mechanism of “airway hyperresponsiveness” in asthma? A) Fixed airway narrowing due to fibrosis B) Increased vagal tone only C) Enhanced smooth-muscle contractility and inflammatory mediator release leading to exaggerated bronchoconstriction to nonspecific stimuli D) Decreased mucus production Answer: C Explanation: In asthma, inflammatory cells release mediators that sensitize airway smooth muscle, causing exaggerated constriction to triggers. Question 53. The “shunting” of blood in severe pneumonia primarily results from: A) Obstruction of bronchioles causing ventilation loss while perfusion remains B) Pulmonary emboli blocking perfusion C) Hyperinflation of alveoli D) Increased airway resistance only Answer: A Explanation: Consolidated alveoli cannot participate in gas exchange; blood flowing through them is shunted, causing hypoxemia. Question 54. In a patient with chronic interstitial lung disease, the diffusion capacity for carbon monoxide (DLCO) is typically:
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A) Elevated due to increased surface area B) Normal because CO diffusion is unrelated to fibrosis C) Decreased because thickened alveolar-capillary membrane impairs gas transfer D) Variable and not clinically useful Answer: C Explanation: Fibrosis thins the effective diffusion surface, lowering DLCO. Question 55. The “Friedlander” (or “honey-comb”) pattern on high-resolution CT is most characteristic of: A) Pulmonary edema B) Idiopathic pulmonary fibrosis C) Bronchiectasis D) Pulmonary embolism Answer: B Explanation: Honey-comb cystic airspaces reflect end-stage fibrotic remodeling in IPF. Question 56. Which of the following is the most important determinant of airway resistance during forced expiration in COPD? A) Airway compliance B) Dynamic airway compression due to increased pleural pressure exceeding airway pressure (equal pressure point) C) Decreased mucus production D) Increased diaphragmatic strength Answer: B Explanation: In COPD, high pleural pressure during forced expiration can exceed airway pressure, causing airway collapse and increased resistance (dynamic compression).
