Regarding the glottis:

Correct Answer: B

Rationale: glottal abductors (posterior cricoarytenoids) contract early in inspiration to widen the glottis. Choice A is false; adductor paralysis (e.g., vocal cord) causes weak voice, not stridor (abductor issue). Choice C is true; abductor paralysis narrows the glottis, risking aspiration. Choice D is wrong; both adductors and abductors are vagus-innervated (recurrent laryngeal), not hypoglossal. Choice E is partially true but not absolute. Abductors, vagus-driven, open the glottis pre-inspiration, ensuring airflow. This timing, critical for ventilation, makes B the accurate statement.

Correct Answer: B

Rationale: dissolved O₂ at PaO₂ = 100 mmHg is ≈0.3 mL/100 mL (solubility = 0.003 mL/mmHg/100 mL · 100 = 0.3). Choice A (0.003) is a typo or misunit. Choice C (3 mL) includes Hb-bound O₂ (≈19 mL with Hb 15 g/dL, SaO₂ 97%), not just dissolved. Choice D (3 mL/mL) is absurdly high. Total O₂ content is ≈20 mL/100 mL, but dissolved fraction is minor; B specifies this accurately per Henry's law.

Correct Answer: D

Rationale: pulmonary stretch receptors (airway smooth muscle) show sustained firing during lung inflation (Hering-Breuer reflex), inhibiting inspiration. Choice A (central) senses chemical changes, not volume. Choice B (carotid) and C (aortic) monitor blood gases. Slow-adapting stretch receptors signal via vagus, prolonging activity with sustained volume, unlike rapidly adapting receptors, making D the match.

Correct Answer: D

Rationale: Choice D is true; irritant receptors adapt rapidly to stimuli (e.g., smoke), triggering cough. Choice A is false; stretch receptors are in smooth muscle. Choice B is wrong; J receptors cause rapid, shallow breathing (e.g., edema). ' irritant impulses are myelinated (vagus). Rapid adaptation distinguishes irritant receptors, making D the accurate statement.

Correct Answer: B

Rationale: long-term 100% O₂ therapy damages Type II pneumocytes, reducing surfactant, not increasing it (O₂ toxicity). Choice A is true; surfactant is ≈90% phospholipids (e.g., DPPC). ' hydrophobic tails face the lumen, hydrophilic heads face the cell, reducing tension. Choice D is accurate; smoking impairs surfactant via oxidative stress. Choice E (edema from absence) is true. Surfactant lowers alveolar surface tension (P = 2T/R), stabilizing lungs, but hyperoxia disrupts production, contradicting B's claim of increase, making it the false statement.