The residents and staff of a nursing home are in a geographical area with reports of confirmed influenza cases. The nurse administrator has decided to offer antiviral medication to all staff and residents as a preventive measure. When is it safe for them to stop taking the drugs?

Correct Answer: B

Rationale: Antiviral prophylaxis (e.g., oseltamivir) in a nursing home during a flu outbreak aims to prevent infection amid high-risk residents and staff. Stopping after 7 days with no new cases aligns with CDC guidance, indicating the outbreak is controlled transmission risk drops when no new infections emerge over a week, roughly the flu's incubation and contagious period. No deaths in 2 days doesn't confirm outbreak end cases could persist. Five days of medication is a treatment duration, not prophylaxis, which often extends longer (e.g., 7–14 days) in outbreaks. Immunity takes weeks via vaccination, not antivirals, which only suppress viral replication. The nurse administrator ensures safety by tying cessation to epidemiological evidence of outbreak resolution, protecting this vulnerable population where flu spreads rapidly, balancing efficacy and drug exposure.

Correct Answer: B

Rationale: Centriacinar emphysema (B) is commonly caused by smoking, affecting proximal acini while sparing distal parts, often with bronchitis'. Pan acinar (A) involves entire acini, linked to α₁-antitrypsin deficiency, not smoking alone. Distal acinar (C) occurs near fibrosis, causing pneumothorax in young adults. Irregular (D) is scarring-related, the most common overall but not smoking-specific. Choice E is false. Page 718 notes centriacinar's association with smokers neutrophil/macrophage elastase damages central lobules, creating normal-emphysematous mosaics, making B the smoking-related type.

Correct Answer: B

Rationale: Bronchial wall smooth muscle is hypertrophic/hyperplastic (B) in asthma, not atrophic. Choice A is false; extrinsic asthma is a Type I hypersensitivity (immune). Choice C is incorrect; IgE, not IgG, drives allergic asthma. Choice D is wrong; vagal receptors are hypersensitive to irritants. Choice E (eosinophil/neutrophil mediators) is true. Page 724 details B's muscle thickening chronic inflammation causes hypertrophy, increasing bronchoconstriction, contrasting with A's mechanism or D's sensitivity error.

Correct Answer: D

Rationale: Silica-induced fibrosis is less pronounced when mixed with other minerals (D), diluting its effect. Choice A is false; silicosis is the most prevalent pneumoconiosis. Choice B is incorrect; crystalline quartz is more fibrogenic than amorphous silica. Choice C is wrong; silica activates macrophages to release mediators (e.g., IL-1), not destroys them. Choice E (late detection) is true. Page 735 notes D's modification mixed dust (e.g., with coal) reduces nodule formation, contrasting with A's prevalence or B's form error.

Correct Answer: B

Rationale: Pulmonary infarcts from emboli are classically hemorrhagic (B), due to dual blood supply. Choice A is false; only 10% cause infarction (most resolve). Choice C is incorrect; death is from acute right heart failure (cor pulmonale). Choice D is wrong; recurrence risk is 30%, not 3%. Choice E (fever) is true. Page 742 details B's morphology red infarcts from bronchial artery bleeding distinguish it over A's frequency or C's heart error.