Author Question: Which of the following statements about alveolar pressure (Palv) during normal quiet breathing is ... (Read 62 times)

go.lag · **on:** Jul 16, 2018

Which of the following statements about alveolar pressure (Palv) during normal quiet breathing is true?

a. It is positive during inspiration and nega-tive during expiration.
b. It is the same as intrapleural pressure (Ppl).
c. It is negative during inspiration and posi-tive during expiration.
d. It always remains less than atmospheric pressure.

Question 2

Which of the following pressure gradients is responsible for maintaining alveolar inflation?

a. Transpulmonary pressure gradient (Palv Ppl)
b. Transthoracic pressure gradient (Ppl Pbs)
c. Transcardiac pressure gradient (Pca Palv)
d. Transrespiratory pressure gradient (Palv Pao)

coyin · **Reply #1 on:** Jul 16, 2018

Answer to Question 1

ANS: C
During inspiration the pleural pressure drops, the transpulmonary pressure gradient widens, caus-ing the alveoli pressure to become sub-atmospheric and gas to enter the lung. During expiration the passive recoil of the lungs cause a supra-atmospheric pressure in the alveoli that causes gas to exit the lung.

Answer to Question 2

ANS: A
Transpulmonary or PL is the pressure difference that maintains alveolar inflation.