ATI LPN
Questions of Respiratory System Questions
Question 1 of 5
Flow of gas in the bronchial tree:
Correct Answer: D
Rationale: Choice D is correct (replacing E); helium (low density) reduces turbulence (lower Reynolds number, Re = ÏvD/μ). Choice A is false; large airways (higher velocity) are more turbulent than small (laminar). Choice B is wrong; turbulent flow scales less than linearly with pressure (not doubled). ' turbulence depends on density, not viscosity (laminar does). Low-density gases decrease Re, easing flow in obstructive disease, making D true.
Question 2 of 5
Which contain glomus cells of two types, with Type I cells containing large amounts of dopamine?
Correct Answer: B
Rationale: carotid bodies contain glomus cells Type I (dopamine-rich, neurotransmitter) and Type II (support) sensing POâ‚‚, PCOâ‚‚, pH. Choice A (central) lacks glomus cells. Choice C (aortic) has similar cells but is less prominent. Choice D (stretch) is mechanical. Carotid bodies, at carotid bifurcations, use Type I cells to signal hypoxia, releasing dopamine, making B the precise match.
Question 3 of 5
The diffusion capacity (DI) of the lung accounts for:
Correct Answer: A
Rationale: diffusion capacity (Dₗ) depends on partial pressure gradient (P1-P2) driving gas transfer (Fick's law: V = D·A·ΔP/T). Choice B (area), C (thickness), and D (constant) are factors, but Dₗ integrates them with ΔP as the flux determinant. Choice E (all) is too broad. Dₗ (e.g., 25 mL/min/mmHg for O₂) measures transfer rate per pressure difference, making A the key variable.
Question 4 of 5
Regarding exercise, which statement is INCORRECT?
Correct Answer: A
Rationale: breathing's energy cost rises to ≈2-5% in exercise (not 10%), though it can reach 10-15% in respiratory disease. Choice B is true; ventilation increases 20x (6 to 120 L/min). ' VO₂ rises ≈15-20x (0.25 to 4-5 L/min in fit adults). Choice D is plausible; VCO₂ can increase disproportionately (e.g., 20-40x) with anaerobic metabolism (RQ > 1). Choice E (P₅₀ up) is true. Normal exercise elevates respiratory work modestly (≈0.5 to 5 kcal/min), not 10% of total (≈50-100 kcal/min), making A overstated and false.
Question 5 of 5
Which of the following does NOT increase synthesis of 2,3-DPG?
Correct Answer: B
Rationale: phosphate deficiency decreases 2,3-DPG synthesis, as phosphate is a substrate in glycolysis (1,3-BPG to 2,3-DPG via mutase). Choice A (growth hormone), C (thyroid hormone), D (exercise), and E (androgens) increase 2,3-DPG by boosting metabolism or hypoxia response, shifting the O₂ curve right (P₅₀ up). In hypoxia (e.g., altitude, exercise), 2,3-DPG rises (e.g., 15 to 20 µmol/g Hb) to aid O₂ unloading. Phosphate scarcity impairs this, reducing levels (e.g., in hypophosphatemia), distinguishing B as the non-stimulator among metabolic enhancers.