Which of the following statements are true about pressure ...

[JMatthes]

Which of the following statements are true about pressure differences in the upright lung?
 
  1. Ppl increases from lung apex to base.
  2. The apical alveoli resting volume is less than at the base.
  3. The transpulmonary pressure gradient is greatest at the apex.
  a. 1 and 3 only
  b. 1, 2, and 3
  c. 2 and 3 only
  d. 1 and 2 only

Question 2

Which of the following will cause an increase in the pressure energy required for inspiration? 1. Increased compliance 2. Increased flow 3. Increased resistance 4. Increased volume
 
  a. 1 and 2 only
  b. 2 and 4 only
  c. 2, 3, and 4 only
  d. 1, 2, 3, and 4

[srodz]

Answer to Question 1

ANS: A
In an adult-sized lung (approximately 30 cm from apex to base), pleural pressure at the apex is approximately 10 cm H2O. At the base, pleural pressure is only about 2.5 cm H2O. Because of these differences, the transpulmonary pressure gradient at the top of the upright lung is greater than it is at the bottom.

Answer to Question 2

ANS: C
High flows and increased Raw increase frictional work. Large tidal volumes increase the elastic component of work. Increased compliance will decrease the elastic component of work and thus is the one exception to an increased energy demand.