The major site of resistance in the bronchial tree is the:

Correct Answer: B

Rationale: medium-sized bronchi (2-4 mm diameter) are the major resistance site due to turbulent flow and peak cumulative resistance before total cross-sectional area rises. Choice A (segmental) and Choice D (large bronchioles) have less resistance due to size or area. Choice C (small bronchi) contributes less individually. Choice E (terminal bronchioles) has high total area, minimizing resistance. Poiseuille's law and airway branching show resistance peaks in medium bronchi, where radius narrows significantly, making B the primary site.

Correct Answer: D

Rationale: CO is diffusion-limited its high Hb affinity and low solubility prevent equilibration in 0.75 s transit. Choice A (Oâ‚‚) is perfusion-limited at rest (equilibrates in 0.25 s). Choice B (Nâ‚‚O) is perfusion-limited (high solubility). Choice C (COâ‚‚) equilibrates fast (20x Oâ‚‚ diffusion). Choice E (halothane) is perfusion-limited. CO's slow uptake (Dâ‚—CO measures lung capacity) distinguishes D as diffusion-limited.

Correct Answer: D

Rationale: advancing age increases compliance (loss of elastic recoil, e.g., emphysema-like), not decreases. Choice A (LV failure) reduces it via edema (stiffer lungs). Choice B (atelectasis) decreases via collapse. Choice C (fibrosis) lowers it (scarring). Choice E (raised PCWP) mimics edema. Aging weakens lung elastin, raising compliance (e.g., 250 vs. 200 mL/cm Hâ‚‚O), distinguishing D as the exception.

Correct Answer: C

Rationale: nitrous oxide (N₂O) is perfusion-limited, not diffusion-limited its high solubility allows rapid equilibration (≈0.1 s) with pulmonary blood flow. Choice A is true; gases diffuse per Fick's law. ' DₗCO₂ ≈ 20x DₗO₂ (600 vs. 25 mL/min/mmHg) due to solubility. Choice D is accurate; CO, diffusion-limited, doesn't equilibrate in 0.75 s (high Hb affinity). Choice E (O₂ perfusion-limited) is true at rest. N₂O's uptake depends on flow, not diffusion barrier, making C the false statement.

Correct Answer: C

Rationale: Congestive heart failure (CHF) increases an adult's risk of acquiring the flu if exposed because it compromises cardiovascular and respiratory function, weakening the body's ability to resist infection. CHF reduces oxygen circulation, impairing immune responses, and fluid buildup in the lungs creates a fertile ground for viral replication and complications like pneumonia. Gallbladder disease and recent cholecystectomy (gallbladder removal) don't directly affect immunity or respiratory health, so they pose minimal flu risk. Deep vein thrombosis impacts blood clotting, not infection susceptibility. Adults with CHF, especially older ones, are more vulnerable to severe flu outcomes due to their chronic condition taxing the body's reserves. The nurse identifies CHF as the key risk factor, as it aligns with evidence linking cardiopulmonary conditions to higher flu morbidity, necessitating preventive measures like vaccination.