ATI LPN
Exam Questions on Respiratory System Questions
Question 1 of 5
Regarding intrapleural pressure, which is INCORRECT?
Correct Answer: C
Rationale: strong inspiration produces intrapleural pressures of -20 to -30 mmHg, not -6 mmHg, which suits quiet breathing. Choice A is true; at rest (end-expiration), pressure is subatmospheric (≈-4 mmHg or -5 cmH₂O) due to lung-chest wall recoil. ' inspiration lowers it further (e.g., -7.5 cmH₂O) as the thorax expands. Choice D is plausible; -2.5 mmHg at bases reflects gravitational gradients (less negative than apex). Strong inspiration, via maximal diaphragmatic and intercostal effort, significantly drops pressure to drive large airflow (e.g., vital capacity). -6 mmHg underestimates this, fitting tidal breathing, not ‘strong' effort. This error misaligns with pleural dynamics, where forceful inspiration amplifies negative pressure, making C the incorrect statement.
Question 2 of 5
Site of most / major airway resistance is:
Correct Answer: D
Rationale: medium-sized bronchi (2-4 mm diameter) are the primary resistance site due to turbulent flow and cumulative cross-sectional area peak. Choice A (trachea) and B (main bronchi) have low resistance (large diameter). Choice C (large bronchi) contributes less. Choice E (bronchioles) has high total area, reducing resistance. Per Poiseuille's law, resistance peaks where radius narrows before area increases, making D the major site.
Question 3 of 5
Regarding pulmonary blood flow:
Correct Answer: C
Rationale: regional pulmonary blood flow differences (apex to base) arise from hydrostatic pressure gradients (West zones). Choice A is false; increased arterial pressure (Pa) reduces resistance via vessel distension. Choice B is true; hypoxia (low POâ‚‚) causes vasoconstriction, but isn't the question's focus. Choice D is wrong; in Zone 1 (apex), PA > Pa > Pv, stopping flow. Gravity increases Pa and Pv from apex (Zone 1, minimal flow) to base (Zone 3, high flow), with resistance adjusting inversely. C accurately describes this vertical distribution.
Question 4 of 5
Which responds quickly to chemicals injected into the pulmonary circulation?
Correct Answer: D
Rationale: J (juxtacapillary) receptors in alveolar walls respond rapidly to pulmonary capillary chemicals (e.g., edema, emboli), causing dyspnea. Choice A (central) senses CSF pH, not pulmonary blood. Choice B (carotid) and C (aortic) monitor systemic arterial changes. Choice D (stretch receptors) responds to lung inflation. J receptors, vagally innervated, detect interstitial changes instantly, unlike systemic chemoreceptors, making F the precise match.
Question 5 of 5
The calibre of extra-alveolar vessels is primarily determined by:
Correct Answer: C
Rationale: extra-alveolar vessel caliber (e.g., arterioles, venules) is primarily determined by lung volume, expanding with inflation (radial traction). Choice A affects alveolar capillaries (Zone 2/3). Choice B (artery pressure) influences flow, not caliber directly. Choice D (output) and E (fluid) are secondary. As volume rises (e.g., FRC to TLC), vessel resistance drops, distinguishing C as the mechanical driver.