KINE 3012 Lecture Notes - Surface Tension
20 Feb 2014
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Document Summary
The law of laplace states pressure = 2 (surface tension) / radius. So since the smaller has a bigger pressure, the air will flow from the smaller alveoli (b) to the bigger alveoli (a). What will then happen is that eventually, the smaller alveoli will just collapse and die down into the bigger alveoli and they will become one. With surfactant (surfactant breaks up water molecule bonds and equalizes surface tension): It has different effects on a large alveolus vs small alveolus. For every alveoli, there is the same # of those type 2 alveolar cells. Surfactant will be more concentrated in the smaller alveolus because of the smaller size of the alveolus. So in the larger alveoli, radius is greater but so is surface tension. So the ratio is dependent on the radius. Therefore, the smaller alveoli will not collapse into the bigger one, and both the alveoli will stay open.
