Author Question: Total lung-thorax compliance in normal subjects is about what level? a. 0.1 L/cm H2O b. 0.2 L/cm ... (Read 58 times)

burchfield96 · **on:** Jul 16, 2018

Total lung-thorax compliance in normal subjects is about what level?

a. 0.1 L/cm H2O
b. 0.2 L/cm H2O
c. 1.0 L/cm H2O
d. 2.0 L/cm H2O

Question 2

In order to inspire to a lung volume greater than approximately 70 of TLC, the inspiratory mus-cles must overcome:

a. the recoil of the lungs.
b. the recoil of both the lungs and the chest wall.
c. the recoil of both the chest walls.
d. the recoil of the alveoli.

Liddy · **Reply #1 on:** Jul 16, 2018

Answer to Question 1

ANS: A
In healthy adults, the compliance of the lungs and chest wall are approximately equal at 0.2 L/cm H2O. However, because the lungs are contained within the thorax, the two systems act as springs pulling against each other. This reduces the compliance of the system to approximately half that of the individual components, or 0.1 L/cm H2O.
Impedance to ventilation by the movement of gas through the airways is called airway resistance.

Answer to Question 2

ANS: B
At the beginning of the breath, the tendency of the chest wall to expand facilitates lung expan-sion. When lung volume nears 70 of the VC, the chest wall reaches its natural resting level. In order to inspire to a lung volume greater than approximately 70 of TLC, the inspiratory muscles must overcome the recoil of both the lungs and the chest wall (see Figure 11-7).