ATI LPN
Respiratory System Practice Questions Questions
Question 1 of 5
The surface area of the lungs is:
Correct Answer: C
Rationale: lung surface area (≈70-100 m²) is ≈30 times the skin's (≈2 m² in adults). Choice A (3x, ≈6 m²) is too low. Choice B (10x, ≈20 m²) underestimates. Choice D (100x, ≈200 m²) overestimates. Choice E is false. The alveolar expanse, via 300 million units, maximizes gas exchange, making C accurate.
Question 2 of 5
Lung compliance increases with:
Correct Answer: A
Rationale: asthma doesn't inherently increase compliance (lung stiffness), but options like emphysema (chronic asthma complication) do via loss of elastic recoil (compliance rises, e.g., 300 mL/cm Hâ‚‚O). Choice B (edema) decreases compliance (stiffer lungs). Choice C (hypertension) affects vessels, not compliance directly. Choice D (atelectasis) and E (fibrosis) reduce compliance (collapse, scarring). Asthma's acute bronchoconstriction doesn't alter compliance, but chronic changes mimic emphysema's high compliance, making A the relative increase among options.
Question 3 of 5
Normally the FEVâ‚ is what percentage of FVC?
Correct Answer: D
Rationale: FEVâ‚ is ≈80% of FVC in healthy adults (FEVâ‚/FVC ratio ≈ 0.75-0.85). Choice A (50%) suggests obstruction (e.g., COPD). Choice B (60%) and C (70%) are low for normals. Choice E (90%) is high, nearing restriction. FEVâ‚ (forced expiratory volume in 1 s) reflects airway patency; FVC (forced vital capacity) is total expirable volume. A ratio of 80% indicates normal flow, making D standard.
Question 4 of 5
With regard to anatomic dead space, all of the following are true EXCEPT:
Correct Answer: A
Rationale: Bohr's method calculates physiological dead space (VD = VT · (PaCO₂ - PECO₂) / PaCO₂), not anatomic (Fowler's N₂ washout does). Choice B is true (≈150 mL). ' deep breaths stretch airways. Choice D is accurate (≈2 mL/kg). Choice E (conducting zone) is true. A's methodological error makes it the exception.
Question 5 of 5
Regarding ventilation / perfusion (V/Q) relationships, which statement is INCORRECT?
Correct Answer: C
Rationale: perfusion decreases more than ventilation from base to apex (gravity), making V/Q higher at apex (e.g., 3 vs. 0.6 at base). Choice A is true (apex V/Q ≈ 3). Choice B is correct (third rib ≈ 1). Choice D is accurate (whole lung ≈ 0.8). Choice E (exercise increases) is true. Ventilation gradient is less steep (4:1 base-to-apex) than perfusion (10:1), reversing C's claim, making it false.