Author Question: Which of the following layers must be traversed by gases moving across the alveolar-capillary ... (Read 75 times)

HudsonKB16 · **on:** Jul 16, 2018

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 · **Reply #1 on:** Jul 16, 2018

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.