PATHOPHYSIOLOGY NU 545-- UNIT 5-- PULMONARY/
KIDNEY I QUESTIONS AND ANSWERS 100% CORRECT |
LATEST UPDATE 2026
1. Which cells provide structure for the alveoli and are the primary site of gas
exchange?
Answer: ✅ Alveolar Type 1 cells.
Rationale: Type 1 pneumocytes are thin squamous cells that form the
alveolar wall and allow gas diffusion.
2. Which cells secrete surfactant in the alveoli?
Answer: ✅ Alveolar Type 2 cells.
Rationale: Type 2 pneumocytes produce surfactant and also serve as
progenitor cells for repair.
3. What is surfactant?
Answer: ✅ A lipoprotein that coats the inner alveolar surface, lowers surface
tension, and prevents alveolar collapse.
Rationale: Surfactant facilitates alveolar expansion during inspiration and
reduces the work of breathing.
4. What is surface tension?
Answer: ✅ The tendency of liquid molecules at an air-liquid interface to
adhere to one another, decreasing surface area.
Rationale: Surface tension creates a collapsing force in the alveoli.
5. According to the Law of Laplace, what determines the pressure required to
inflate a sphere?
Answer: ✅ P = 2T/r, where T is surface tension and r is radius.
Rationale: Smaller alveoli require greater pressure to inflate if surfactant is
absent.
,6. What is alveolar ventilation?
Answer: ✅ The volume of fresh air reaching the alveoli per minute,
calculated as (tidal volume – dead space) × respiratory rate.
Rationale: It determines effective gas exchange, not just total minute
ventilation.
7. When is surfactant first produced in the fetus?
Answer: ✅ Between 20 and 24 weeks of gestation.
Rationale: Surfactant is secreted into fetal airways by about 30 weeks and
is usually adequate by 34–35 weeks.
8. What is lung compliance?
Answer: ✅ The distensibility of the lungs; the change in lung volume for a
given change in pressure.
Rationale: High compliance means the lungs expand easily; low compliance
means they are stiff.
9. What is elastic recoil?
Answer: ✅ The tendency of the lungs to return to their original shape after
inflation.
Rationale: Loss of elastic recoil contributes to air trapping in emphysema.
10. What is airway resistance?
Answer: ✅ The opposition to airflow through the respiratory passages.
Rationale: Airway radius is the most important factor; small decreases in
radius greatly increase resistance.
11. What is the normal ventilation-perfusion (V/Q) ratio?
Answer: ✅ About 0.8.
, Rationale: Normal V/Q is approximately 4 L/min ventilation to 5 L/min
perfusion.
12. What is a pulmonary shunt?
Answer: ✅ Perfusion without ventilation, where V/Q = 0.
Rationale: Blood passes through unventilated alveoli and is not oxygenated.
13. What is alveolar dead space?
Answer: ✅ Ventilation without perfusion, where V/Q = infinity.
Rationale: Air reaches alveoli but no blood flow occurs, so gas exchange
does not happen.
14. What is hypoxemia?
Answer: ✅ Low partial pressure of oxygen in arterial blood (PaO2 < 80 mm
Hg).
Rationale: Hypoxemia can result from V/Q mismatch, shunt, diffusion
defects, or hypoventilation.
15. What is hypercapnia?
Answer: ✅ Elevated partial pressure of carbon dioxide in arterial blood
(PaCO2 > 45 mm Hg).
Rationale: Hypercapnia usually indicates alveolar hypoventilation.
16. What is the key difference between obstructive and restrictive lung
disease?
Answer: ✅ Obstructive disease increases airway resistance; restrictive
disease decreases lung compliance.
Rationale: Obstructive disorders have reduced FEV1/FVC, while restrictive
disorders reduce total lung volumes.
17. What is the primary pathophysiology of asthma?
KIDNEY I QUESTIONS AND ANSWERS 100% CORRECT |
LATEST UPDATE 2026
1. Which cells provide structure for the alveoli and are the primary site of gas
exchange?
Answer: ✅ Alveolar Type 1 cells.
Rationale: Type 1 pneumocytes are thin squamous cells that form the
alveolar wall and allow gas diffusion.
2. Which cells secrete surfactant in the alveoli?
Answer: ✅ Alveolar Type 2 cells.
Rationale: Type 2 pneumocytes produce surfactant and also serve as
progenitor cells for repair.
3. What is surfactant?
Answer: ✅ A lipoprotein that coats the inner alveolar surface, lowers surface
tension, and prevents alveolar collapse.
Rationale: Surfactant facilitates alveolar expansion during inspiration and
reduces the work of breathing.
4. What is surface tension?
Answer: ✅ The tendency of liquid molecules at an air-liquid interface to
adhere to one another, decreasing surface area.
Rationale: Surface tension creates a collapsing force in the alveoli.
5. According to the Law of Laplace, what determines the pressure required to
inflate a sphere?
Answer: ✅ P = 2T/r, where T is surface tension and r is radius.
Rationale: Smaller alveoli require greater pressure to inflate if surfactant is
absent.
,6. What is alveolar ventilation?
Answer: ✅ The volume of fresh air reaching the alveoli per minute,
calculated as (tidal volume – dead space) × respiratory rate.
Rationale: It determines effective gas exchange, not just total minute
ventilation.
7. When is surfactant first produced in the fetus?
Answer: ✅ Between 20 and 24 weeks of gestation.
Rationale: Surfactant is secreted into fetal airways by about 30 weeks and
is usually adequate by 34–35 weeks.
8. What is lung compliance?
Answer: ✅ The distensibility of the lungs; the change in lung volume for a
given change in pressure.
Rationale: High compliance means the lungs expand easily; low compliance
means they are stiff.
9. What is elastic recoil?
Answer: ✅ The tendency of the lungs to return to their original shape after
inflation.
Rationale: Loss of elastic recoil contributes to air trapping in emphysema.
10. What is airway resistance?
Answer: ✅ The opposition to airflow through the respiratory passages.
Rationale: Airway radius is the most important factor; small decreases in
radius greatly increase resistance.
11. What is the normal ventilation-perfusion (V/Q) ratio?
Answer: ✅ About 0.8.
, Rationale: Normal V/Q is approximately 4 L/min ventilation to 5 L/min
perfusion.
12. What is a pulmonary shunt?
Answer: ✅ Perfusion without ventilation, where V/Q = 0.
Rationale: Blood passes through unventilated alveoli and is not oxygenated.
13. What is alveolar dead space?
Answer: ✅ Ventilation without perfusion, where V/Q = infinity.
Rationale: Air reaches alveoli but no blood flow occurs, so gas exchange
does not happen.
14. What is hypoxemia?
Answer: ✅ Low partial pressure of oxygen in arterial blood (PaO2 < 80 mm
Hg).
Rationale: Hypoxemia can result from V/Q mismatch, shunt, diffusion
defects, or hypoventilation.
15. What is hypercapnia?
Answer: ✅ Elevated partial pressure of carbon dioxide in arterial blood
(PaCO2 > 45 mm Hg).
Rationale: Hypercapnia usually indicates alveolar hypoventilation.
16. What is the key difference between obstructive and restrictive lung
disease?
Answer: ✅ Obstructive disease increases airway resistance; restrictive
disease decreases lung compliance.
Rationale: Obstructive disorders have reduced FEV1/FVC, while restrictive
disorders reduce total lung volumes.
17. What is the primary pathophysiology of asthma?
