Respiratory 16 Flashcards
What accounts for 2/3 of the last elastic recoil in the lungs?
The surface tension at the air water interface
How does surface tension affect lung compliance?
It decreases lung compliance
How does surface tension cause the lungs to collapse?
Water molecules at the surface of a liquid-gas interface are attracted strongly to water molecules within the liquid mass causing them to recoil
What is the internal surface of the alveoli lined with?
A thin layer of fluid
Why would a pressure volume curve be a lot steeper in a saline filled lung?
Because surface tension is not involved in the process only the elastic recoil so the lung is considered more compliant
What is air entering the lungs humidified and saturated with?
Water vapour and body temperature
How does Surface tension affect an alveoli?
It decreases the volume of compressible gas inside the alveoli and increases pressure
What does Laplace’s equation describe?
At equilibrium, the tendency of increased pressure to expand the alveolus balancing the tendency of surface tension to collapse
How does the pressure needed to keep the alveoli open change with the size of a sphere?
A small sphere required higher pressure in order to keep the sphere inflated
What remains constant in alveoli of different sizes?
The surface tension
