Author Question: For a given transpulmonary pressure gradient and inflation time, which of the following lung units ... (Read 68 times)

SAVANNAHHOOPER23 · **on:** Jul 16, 2018

For a given transpulmonary pressure gradient and inflation time, which of the following lung units would exhibit the greatest change in volume?

a. A unit with high resistance and low com-pliance
b. A unit with high resistance and normal compliance
c. A unit with normal resistance and low compliance
d. A unit with normal resistance and normal compliance

Question 2

Which of the following occurs during normal inspiration?

a. Alveoli at the apexes expand less than those at the bases.
b. Alveoli at the apexes expand more than those at the bases.
c. Alveoli at the bases expand less than those at the apexes.
d. Central alveoli expand more than those at the periphery.

kbennett34 · **Reply #1 on:** Jul 16, 2018

Answer to Question 1

ANS: D
The ventilation going to lung units with either long or short time constants is less than that re-ceived by units with normal compliance and resistance.

Answer to Question 2

ANS: A
Despite their higher volume, alveoli at the apexes expand less during inspiration than alveoli at the bases or periphery. This is due to their respective positions on the pressure volume curves (Figure 11-14). The apical alveoli are on the flatter or less compliant portion of the curve and thus for any change in pressure there is only a small change in volume. The alveoli in the lung base are on the steep part of the curve, so even small changes in pressure result in comparatively large changes in volume.