True statement relating to compliance of
lung:
a) Increased by surfactant
b) Decreased in emphysema
c) At height of inspiration compliance is less
d) It can be measured by measuring intrapleural pressure at
different lung volume
e) None
Correct Answer - A:C:D
Ans. (A) Increased by surfactant (C) At height of inspiration
compliance is less (D) It can be measured by measuring
intrapleural pressure at different lung volume
[Ref: Ganong 25th/629-32,24th/629-33; Guyton llth /473-75; A. K.
Jain 5th/437]
Lung compliance:
Measured by measuring intrapleural pressure at different lung
volume.
An important factor affecting the compliance of the lungs is the
surface tension of the film of fluid that lines the alveoli.
Deficiency of surfactant-less compliance; more surfactant-more
compliance.
Compliance decreases with the inflation of the lungs as more
pressure is required to distend the already distended lung.
The curve is shifted downward and to the right (compliance is
decreased) by pulmonary congestion and interstitial pulmonary
fibrosis; pulmonary fibrosis is a progressive disease of unknown
cause in which there is stiffening and scarring of the lung.
The curve is shifted upward and to the left (compliance is increased)
in emphysema.