6 What are the forces that resist alveolar expansion during

6) What are the forces that resist alveolar expansion during a full inspiration? How are these forces reduced by alveolar cells and overcome by diaphragm contraction.

Solution

The forces that resist alveolar expansion during a full inspiration are

(1) the natural tendency of the alveoli to recoil, and

(2) the surface Tension (T) of the alveoli

These forces are reduced by alveolar cells and overcome by diaphragm contraction due to:

(1) Diaphragm contract and rib cage expands, this creates positive pressure within the alveoli

(2) Negative intra-pleural pressure tend to aid expansion of the alveoli

(3) With the enlargement of the alveoli, the surface forces are reduced during inhalation.