Which is not inactivated by the lungs?

Correct Answer: D

Rationale: vasopressin (ADH) passes through the lungs unchanged. Choice A (serotonin) is inactivated by monoamine oxidase. Choice B (bradykinin) is broken down by ACE. Choice C (leukotrienes) are metabolized or excreted. Choice D (prostaglandin Eâ‚‚) is inactivated by pulmonary enzymes. The lung's endothelium clears amines, peptides, and eicosanoids, but vasopressin, a systemic hormone, resists metabolism, maintaining its antidiuretic role. E's inert passage aligns with pulmonary metabolic selectivity.

Correct Answer: A

Rationale: no consistent evidence shows males eliminate carboxyhemoglobin (COHb) faster than females elimination depends on Oâ‚‚ partial pressure and ventilation. Choice B is true; ambient air compresses, but Oâ‚‚ is 100%. ' dissolved Oâ‚‚ rises (e.g., 6 mL/100 mL at 3 atm). Choice D is accurate; therapy uses 2-3 atm. Choice E (toxicity) is plausible. Hyperbaric Oâ‚‚ accelerates COHb clearance equally by POâ‚‚, not sex, making A the false claim.

Correct Answer: C

Rationale: carotid bodies markedly increase firing when arterial PO₂ falls below 60 mmHg, not 70 mmHg, which is a less pronounced threshold. Choice A is true; central chemoreceptors reside in the medulla, sensing CSF pH. ' hypoxia (via peripheral chemoreceptors) enhances CO₂ sensitivity, amplifying ventilation. Choice D is accurate; carotid bodies have exceptionally high blood flow (≈2000 mL/min/100 g) for rapid gas sensing. Choice E (CO₂ dominance) is also true. The carotid bodies' steep response curve begins at ≈60 mmHg, driving significant respiratory stimulation below this level (e.g., SaO₂ < 90%), as seen in hypoxia studies. At 70 mmHg, stimulation is milder, making C's threshold overstated and thus the incorrect statement.

Correct Answer: A

Rationale: physiological dead space (anatomic + alveolar) equals anatomical dead space (≈150 mL) in healthy lungs at rest alveolar dead space is negligible. Choice B is true; base ventilates more (gravity). Choice C is correct (7 mL/kg, ≈500 mL for 70 kg). Choice D is accurate; resistance drops with volume (airway stretch). Choice E (20x increase) is true. Normal Vₓ/Vₜ (0.3) matches anatomic dead space, making A's ‘larger' claim false.

Correct Answer: B

Rationale: Cough suppressants are medications that reduce the cough reflex, which can be helpful for sleep but may hinder airway clearance during the day when the body needs to expel mucus. For an adolescent with flu symptoms, promoting airway clearance is critical to prevent mucus buildup, which could lead to complications like pneumonia. Using cough suppressants at night allows the client to rest while still enabling productive coughing during the day to clear the airways. Morning, evening, or afternoon use could suppress coughing when it's most needed to expel mucus, especially since flu often involves increased respiratory secretions. The nurse's focus is on balancing symptom relief with the body's natural defense mechanisms, and nighttime use aligns with this goal by prioritizing rest without fully inhibiting airway clearance throughout the day. This approach supports recovery by ensuring mucus is cleared effectively while minimizing discomfort during sleep.