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
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.
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