ATI LPN
Introduction of Respiratory System NCLEX Questions PN Questions
Question 1 of 5
Most of the oxygen being transported by blood:
Correct Answer: C
Rationale: Oxygen is reversibly bound to haemoglobin (C) . Haemoglobin in RBCs (5 billion/mL) carries 98% of O2 (20 mL/dL), binding 4 molecules/O2 via iron. Plasma (A) holds 2%. Glucose (B) isn't an O2 carrier. Heartbeat energy (D) uses ATP, not O2 directly. C's capacity unlike A's minor role ensures tissue delivery, per physiology.
Question 2 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 3 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 4 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.
Question 5 of 5
In primary atypical (presumably viral) pneumonia the most common of the following blood findings is:
Correct Answer: C
Rationale: Cold agglutination (C) is the most common blood finding in primary atypical pneumonia, often viral (e.g., Mycoplasma pneumoniae). This autoimmune reaction antibodies clump RBCs at low temperatures reflects infection-induced immune activation, detectable in 50-70% of cases. Leucocytosis (A) suits bacterial pneumonia, not viral, where counts are normal or low. Sheep RBC agglutination (B) isn't standard; cold agglutinins are specific. Secondary anemia (D) may occur late, not primarily. Latex fixation tests rheumatoid factor, unrelated here. Cold agglutinins, peaking in week 2-3, aid diagnosis when sputum or x-rays are inconclusive, distinguishing atypical from bacterial pneumonia in clinical hematology.