ATI LPN
Introduction of Respiratory System NCLEX Questions PN Questions
Question 1 of 5
Which of these symptoms is common is all COPDs?
Correct Answer: A
Rationale: Dyspnea (A) is common in all COPD . Airflow obstruction raises work of breathing (RR >20). Dry cough (B) fits emphysema. Recoil loss (C) is emphysema-specific. Coexistence (D) varies. A's universality unlike C's specificity holds, per document.
Question 2 of 5
In the presence of active surfactants, all of the following are expected to decrease EXCEPT?
Correct Answer: B
Rationale: Surfactant lowers alveolar surface tension (C) from 30 dynes/cm to 5, reducing collapse tendency (A) and work of breathing. Lung compliance (B) increases (normal 0.2 L/cm H2O to 0.5), not decreases, as expansion eases. In 300 million alveoli, surfactant's dipalmitoylphosphatidylcholine stabilizes, countering Laplace's law (P = 2T/r). B's rise unlike A's or D's fall enhances ventilation efficiency, per physiology (Q29).
Question 3 of 5
Which of the following is the most factor that can increase the volume of air entering the lung?
Correct Answer: A
Rationale: Pressure gradient (A) drives air into lungs . Inspiration drops intrapulmonary pressure (e.g., -1 mmHg below atmospheric, 760 mmHg), via diaphragm contraction (Q22). A 2 mmHg gradient moves ~500 mL (Vt). Action potentials (B) initiate muscle firing, but gradient magnitude not nerve signal strength dictates volume (Boyle's law: P1V1 = P2V2). C overcomplicates A alone suffices. D reduces flow. A's primacy unlike B's indirect role governs ventilation, per respiratory mechanics.
Question 4 of 5
If dead space is one third of the tidal volume and arterial PCO2 is 45 mmHg, what is the mixed expired PCO2?
Correct Answer: B
Rationale: Mixed expired PCO2 (PECO2) is 30 mmHg. If Vd = Vt/3, then Va = 2Vt/3. Bohr's equation: Vd/Vt = (PaCO2 - PECO2) / PaCO2. Given PaCO2 = 45 mmHg, Vd/Vt = 1/3 → 1/3 = (45 - PECO2) / 45 → PECO2 = 45 - 15 = 30 mmHg. PECO2 reflects alveolar (40 mmHg) and dead space (0 mmHg) mix. B's 30 unlike A's 20 or D's 45 fits 1/3 dead space dilution, per gas mixing physiology (Q12).
Question 5 of 5
Which of the following is not correct regarding exhalation (expiration)?
Correct Answer: D
Rationale: Exhalation doesn't start with expiratory muscle relaxation. Passive expiration (A) uses lung recoil (C, true, -5 cm H2O intrapleural). Active expiration (B) engages muscles (e.g., abdominals). D's trigger relaxation fits inspiration's end; expiration begins when inspiratory muscles (diaphragm) relax, raising pressure (+1 mmHg). COPD hinders expiration (E, true, Q65). D's error unlike A's norm misaligns timing, per physiology.