In emphysema (old paper)

Correct Answer: C

Rationale: The protease-antiprotease mechanism (C) is the most plausible explanation for emphysema'. Choice A is false; α₁-antitrypsin deficiency causes panacinar emphysema, not protects. Choice B is true; centriacinar destruction overinflates via obstruction. Choice D is incorrect; macrophages increase in alveolar spaces, not bronchi. Choice E (elastase up with radicals) is true but not listed. Page 721 links smoking's oxidative stress and neutrophil elastase to alveolar damage, with α₁-antitrypsin's protective role overwhelmed, making C's imbalance theory central, unlike A's reversal or D's location error.

Correct Answer: C

Rationale: Sarcoidosis causes bilateral hilar lymphadenopathy (C) in 90% of cases. Choice A is false; its cause is unknown (possible immune dysregulation), not silica (pneumoconiosis). Choice B is incorrect; granulomas are non-caseating. Choice D is wrong; lung pathology is most common, followed by eye/skin lesions. Choice E (more in women) is true. Page 737 confirms C's radiographic hallmark hilar nodes distinguish it, unlike A's etiology or B's necrosis error.

Correct Answer: A

Rationale: S pneumoniae is endogenous flora in 20% of adults (A), colonizing the oropharynx. Choice B is true; bacterial/viral causes predominate. Choice C is false; 20-30% have positive blood cultures, not 50%. Choice D is incorrect; resistance to penicillin is variable. Choice E (H influenzae not overtaking) is true. Page 748 confirms A's carriage rate common in healthy adults, it's the leading pathogen, distinguishing it over C's exaggeration or D's sensitivity error.

Correct Answer: C

Rationale: Gram-negative rods are common nosocomial pneumonia pathogens (C), e.g., Klebsiella, Pseudomonas. Choice A is false; they're common with severe disease (e.g., intubation). Choice B is incorrect; antibiotics are a risk factor, not preventative. Choice D is wrong; Strep pneumoniae is minor in hospitals. Choice E (life-threatening) is true. Page 752 lists C's dominance gram-negative 'poo bugs' thrive in hospital settings, unlike A's broad claim or B's prevention error.

Correct Answer: A

Rationale: Goblet cells are specialized epithelial cells in mucous membranes, like those in the respiratory tract, that secrete mucus to trap pathogens and debris, protecting underlying tissues. Macrophages are immune cells that engulf pathogens, not mucus producers. Phagocytes, a broader immune cell category, also lack mucus-secreting roles. Ciliated epithelial cells move mucus via cilia but don't produce it working with goblet cells to clear airways. Goblet cells' mucus is vital for the mucociliary escalator, a defense mechanism in the lungs and nasal passages, where mucus captures particles and cilia sweep them out. This division of labor ensures respiratory surfaces stay moist and clean, preventing infection and irritation, a fundamental concept in understanding respiratory histology and immunity.