PHYS20008 Lecture Notes - Lecture 15: Pulmonary Compliance, Airway Resistance, Surface Tension
21 Jul 2019
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Document Summary
Airway resistance increases with: increase in length of airway increase in viscosity of air. Decrease in airway diameter: narrower -> harder to fit things through. Lung compliance affected by alveolar surface tension surface tension due to h bonds b/w water molecules inward pull inside the alveolus. Water molecules more attracted to other water molecules than gases in air at air-fluid interface. Attraction b/w water molecules resists any force that increases its surface area, thus opposes expansion of alveolus creating surface tension liquid surface area tends to shrink due to attraction b/w water molecules, thus reducing alveolus size. Law of laplace larger diameter -> less resistance if surface tension is the same, pressure in smaller bubble is greater. Alveoli are attached if one pulls inwards, the other ones will pull back on it. Lung volumes & capacities tidal volume: normal breath (1/2l) inspiratory reserve volume.
