The lungs adhere to the wall of the thorax because a the int

The lungs adhere to the wall of the thorax because:

a) the intrapleural pressure is always positive.

b) the alveolar pressure is always positive.

c) the transpulmonary pressure is always positive.

d) there is connective tissue between them.

e) the alveolar pressure is always negative.

Solution

c) the transpulmonary pressure is always positive.

Transpulmonary pressure is the difference between the alveolar pressure and the intrapleural pressure in the lungs.

If \'transpulmonary pressure\' = 0 (alveolar pressure = intrapleural pressure), such as when the lungs are removed from the chest cavity or air enters the intrapleural space (apneumothorax), the lungs collapse as a result of their inherent elastic recoil. Under physiological conditions the transpulmonary pressure is always positive; intrapleural pressure is always negative and relatively large, while alveolar pressure moves from slightly negative to slightly positive as a person breathes. For a given lung volume the transpulmonary pressure is equal and opposite to the elastic recoil pressure of the lung.