RESPIRATORY PHYSIOLOGY
Practice Questions: Alveolar Gas Exchange

PRACTICE EXAMINAITON QUESTIONS:  Alveolar Gas Exchange

1. What would be the expected effect of pulmonary edema on the pulmonary diffusing capacity for oxygen (DO2) and carbon dioxide (DCO2)

A. reduce DO2 and reduce DCO2
B. reduce DO2 but no effect on DCO2
C. reduce DCO2 but no effect on DO2
D. no effect on either DO2 or DCO2

E. no effect on either DO2 or DCO2 unless diffusing area is reduced also

2. At which of the following sites is the partial pressure of carbon dioxide (PCO2) highest?

A. exhaled gas
B. alveolar gas
C. systemic arterial blood
D. systemic venous blood

E. about the same in all of the above (40 mmHg)

3. At which of the following sites is the partial pressure of oxygen (PO2) highest?

A. exhaled gas
B. anatomical dead space at the end of expiration
C. anatomical dead space at the end of inspiration
D. alveolar gas
E. about the same in all of the above (100 mmHg)

4. An individual who breaths through a hose or tube while keeping his tidal volume normal would be expected to have an increased (compared to normal) of which of the following?

A. dead space
B. wasted ventilation
C. systemic arterial carbon dioxide content (Ca-CO2)
D. all of the above
E. only A and B above

5. At the top of a 3000 meter high mountain, which of the following alveolar partial pressures would be expected to be lower than normal?  (Remember that barometric pressure, PB, decreases as one goes higher.)

A. oxygen (PA-O2)
B. carbon dioxide (PA-CO2)
C. water vapor (PA-H2O)
D. all of the above
E. only A and B above

6. Reduction of the pulmonary diffusing capacity to one-fourth of its normal value would be expected to have what effect on systemic arterial oxygen and carbon dioxide partial pressures (compared to normal)?

A. decrease Pa-O2 and decrease Pa-CO2
B. decrease Pa-O2 and increase Pa-CO2
C. increase Pa-O2 and decrease Pa-CO2

D. increase Pa-O2 and increase Pa-CO2
E. decrease Pa-O2 but no change in Pa-CO2

7. At rest, wasted ventilation as a percent of total ventilation of 30% is

A. above normal
B. below normal
C. within the normal range