Which of the following gases would diffuse fastest across the ...

[Frost2351]

Which of the following gases would diffuse fastest across the alveolar-capillary membrane?
 
  a. Air
  b. Carbon dioxide
  c. O2
  d. Nitrogen

Question 2

Assuming a constant FiO2 and carbon dioxide production, which of the following statements is correct?
 
  a. An increased PACO2 will result in and increased PAO2.
  b. Increased FIO2 blows off carbon dioxide.
  c. Increases in alveolar ventilation (VA) decrease the PACO2 and increase the PAO2.
  d. The PAO2 varies proportionally with the PACO2.

[Liddy]

Answer to Question 1

ANS: B
Carbon dioxide diffuses approximately 20 times faster across the alveolar-capillary membrane than does O2, because of its much higher solubility in plasma.

Answer to Question 2

ANS: C
With a constant carbon dioxide production, a decrease in alveolar ventilation (VA) simultaneously raises the PACO2 and lowers the PAO2.