Which of the following layers must be traversed by gases moving ...

[HudsonKB16]

Which of the following layers must be traversed by gases moving across the alveolar-capillary membrane?
 
  1. Alveolar epithelial membrane
  2. Capillary endothelial membrane
  3. Interstitial space
  4. Transbronchial radial tethering mechanisms
  a. 1, 2, and 3 only
  b. 1, 2, and 4 only
  c. 2 and 3 only
  d. 1, 2, 3, and 4

Question 2

When is the rate of gaseous diffusion across a biological membrane decreased?
 
  a. The diffusion distance is small.
  b. The gas diffusion constant increases.
  c. The partial pressure gradient is low.
  d. The surface area is large.

[paavo]

Answer to Question 1

ANS: A
For carbon dioxide or O2 to move between the alveoli and the pulmonary capillary blood, the following three barriers must be penetrated: (1) alveolar epithelium, (2) interstitial space, and (3) capillary endothelium.

Answer to Question 2

ANS: C
Given that the area of and distance across the alveolar-capillary membrane are relatively constant in healthy people, diffusion in the normal lung mainly depends on gas pressure gradients.

[HudsonKB16]

Excellent

[bdobbins]

Thanks for the timely response, appreciate it