NU 545 PATHOPHYSIOLOGY — UNIT 5: RESPIRATORY
AND RENAL EXAM Actual Exam Complete Questions
and Answers Detailed Rationales Pass Guaranteed -
A+ Graded
══════════════════════════════════════
SECTION 1: RESPIRATORY STRUCTURE & FUNCTION Q1 – Q10
══════════════════════════════════════
Question 1 of 50
A 68-year-old male with COPD has a PaO2 of 62 mmHg and an oxygen saturation of
88%. His hemoglobin is 15 g/dL. A colleague asks why the PaO2 is disproportionately
lower than the saturation might suggest. What is the best explanation?
A. The Haldane effect shifting the oxyhemoglobin curve to the right
B. The Bohr effect reducing hemoglobin affinity at the tissue level
C. The sigmoid shape of the oxyhemoglobin dissociation curve ✓ CORRECT
D. Decreased 2,3-DPG from chronic hypoxemia
Correct Answer: C
Rationale: The oxyhemoglobin dissociation curve is sigmoid, meaning that on the steep
portion a small drop in PaO2 causes a large fall in saturation, while on the plateau a
large PaO2 change causes little saturation change. In this case the patient is on the
steep part of the curve where PaO2 and saturation decline together. The Haldane effect
describes CO2 transport, not the PaO2-to-saturation relationship, and chronic
hypoxemia actually increases 2,3-DPG rather than decreasing it.
Question 2 of 50
,A 28-year-old female arrives in the emergency department after a car crash. Breath
sounds are absent on the left and the trachea is deviated to the right. Chest X-ray
confirms a tension pneumothorax. Which pathophysiologic mechanism explains the
tracheal deviation?
A. Decreased surface tension in the affected lung causing collapse
B. Surfactant deficiency allowing alveolar flooding
C. Increased compliance of the mediastinal pleura
D. Increased intrapleural pressure on the affected side collapsing the lung and pushing
the mediastinum ✓ CORRECT
Correct Answer: D
Rationale: In a tension pneumothorax, air enters the pleural space and cannot escape,
creating a positive intrapleural pressure that collapses the lung and displaces the
mediastinum away from the affected side. This compromises venous return and
contralateral lung expansion. Decreased surface tension and surfactant deficiency are
not mechanisms of traumatic pneumothorax, and mediastinal pleural compliance does
not drive the life-threatening shift.
Question 3 of 50
A patient with a pulmonary embolism affecting a large segment of the right lung has an
ABG showing PaCO2 38 mmHg and PaO2 72 mmHg. Which physiologic mechanism
best explains the hypoxemia?
A. Diffusion limitation across a thickened alveolar membrane
B. Shunt physiology with perfusion of non-ventilated alveoli
C. Increased alveolar dead space with relative hypoventilation of remaining units ✓
CORRECT
D. Bronchial constriction causing complete airway obstruction
Correct Answer: C
, Rationale: A pulmonary embolism increases alveolar dead space by ventilating areas
that are no longer perfused, and the remaining lung units may have relative
hypoventilation for their perfusion, leading to V/Q mismatch and hypoxemia. Pure shunt
physiology implies perfusion without any ventilation, which is not the primary
mechanism in uncomplicated embolism, and diffusion limitation is characteristic of
interstitial lung disease rather than vascular obstruction.
Question 4 of 50
A 5-year-old with asthma has a reduced FEV1/FVC ratio but a normal total lung capacity
on pulmonary function testing. This pattern indicates:
A. Restrictive physiology from pulmonary fibrosis
B. Obstructive pattern with air trapping ✓ CORRECT
C. Neuromuscular weakness affecting inspiratory capacity
D. Reduced lung compliance from surfactant loss
Correct Answer: B
Rationale: A reduced FEV1/FVC ratio with preserved or increased total lung capacity is
the hallmark of obstructive lung disease such as asthma, where airway narrowing slows
expiration and causes air trapping. Restrictive disease reduces both FEV1 and FVC
proportionally, preserving the ratio, and neuromuscular weakness reduces all lung
volumes without preferentially affecting the ratio.
Question 5 of 50
A healthy climber ascends to 12,000 feet and notices a gradual increase in ventilation
over the first few hours. Which receptor primarily mediates this response to altitude?
A. Peripheral chemoreceptors in the carotid bodies responding to hypoxemia ✓
CORRECT
B. Central chemoreceptors in the medulla responding to decreased PaCO2
C. Stretch receptors in the lung parenchyma responding to deflation
AND RENAL EXAM Actual Exam Complete Questions
and Answers Detailed Rationales Pass Guaranteed -
A+ Graded
══════════════════════════════════════
SECTION 1: RESPIRATORY STRUCTURE & FUNCTION Q1 – Q10
══════════════════════════════════════
Question 1 of 50
A 68-year-old male with COPD has a PaO2 of 62 mmHg and an oxygen saturation of
88%. His hemoglobin is 15 g/dL. A colleague asks why the PaO2 is disproportionately
lower than the saturation might suggest. What is the best explanation?
A. The Haldane effect shifting the oxyhemoglobin curve to the right
B. The Bohr effect reducing hemoglobin affinity at the tissue level
C. The sigmoid shape of the oxyhemoglobin dissociation curve ✓ CORRECT
D. Decreased 2,3-DPG from chronic hypoxemia
Correct Answer: C
Rationale: The oxyhemoglobin dissociation curve is sigmoid, meaning that on the steep
portion a small drop in PaO2 causes a large fall in saturation, while on the plateau a
large PaO2 change causes little saturation change. In this case the patient is on the
steep part of the curve where PaO2 and saturation decline together. The Haldane effect
describes CO2 transport, not the PaO2-to-saturation relationship, and chronic
hypoxemia actually increases 2,3-DPG rather than decreasing it.
Question 2 of 50
,A 28-year-old female arrives in the emergency department after a car crash. Breath
sounds are absent on the left and the trachea is deviated to the right. Chest X-ray
confirms a tension pneumothorax. Which pathophysiologic mechanism explains the
tracheal deviation?
A. Decreased surface tension in the affected lung causing collapse
B. Surfactant deficiency allowing alveolar flooding
C. Increased compliance of the mediastinal pleura
D. Increased intrapleural pressure on the affected side collapsing the lung and pushing
the mediastinum ✓ CORRECT
Correct Answer: D
Rationale: In a tension pneumothorax, air enters the pleural space and cannot escape,
creating a positive intrapleural pressure that collapses the lung and displaces the
mediastinum away from the affected side. This compromises venous return and
contralateral lung expansion. Decreased surface tension and surfactant deficiency are
not mechanisms of traumatic pneumothorax, and mediastinal pleural compliance does
not drive the life-threatening shift.
Question 3 of 50
A patient with a pulmonary embolism affecting a large segment of the right lung has an
ABG showing PaCO2 38 mmHg and PaO2 72 mmHg. Which physiologic mechanism
best explains the hypoxemia?
A. Diffusion limitation across a thickened alveolar membrane
B. Shunt physiology with perfusion of non-ventilated alveoli
C. Increased alveolar dead space with relative hypoventilation of remaining units ✓
CORRECT
D. Bronchial constriction causing complete airway obstruction
Correct Answer: C
, Rationale: A pulmonary embolism increases alveolar dead space by ventilating areas
that are no longer perfused, and the remaining lung units may have relative
hypoventilation for their perfusion, leading to V/Q mismatch and hypoxemia. Pure shunt
physiology implies perfusion without any ventilation, which is not the primary
mechanism in uncomplicated embolism, and diffusion limitation is characteristic of
interstitial lung disease rather than vascular obstruction.
Question 4 of 50
A 5-year-old with asthma has a reduced FEV1/FVC ratio but a normal total lung capacity
on pulmonary function testing. This pattern indicates:
A. Restrictive physiology from pulmonary fibrosis
B. Obstructive pattern with air trapping ✓ CORRECT
C. Neuromuscular weakness affecting inspiratory capacity
D. Reduced lung compliance from surfactant loss
Correct Answer: B
Rationale: A reduced FEV1/FVC ratio with preserved or increased total lung capacity is
the hallmark of obstructive lung disease such as asthma, where airway narrowing slows
expiration and causes air trapping. Restrictive disease reduces both FEV1 and FVC
proportionally, preserving the ratio, and neuromuscular weakness reduces all lung
volumes without preferentially affecting the ratio.
Question 5 of 50
A healthy climber ascends to 12,000 feet and notices a gradual increase in ventilation
over the first few hours. Which receptor primarily mediates this response to altitude?
A. Peripheral chemoreceptors in the carotid bodies responding to hypoxemia ✓
CORRECT
B. Central chemoreceptors in the medulla responding to decreased PaCO2
C. Stretch receptors in the lung parenchyma responding to deflation
