PHYS20008 Lecture Notes - Lecture 19: Nasal Cavity, Thoracic Wall, Ph
23 Jul 2018
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Water loss (and heat elimination in animals) Cartilage is wrapped around large airways to hold them ope(cid:374) (cid:271)ut (cid:373)ea(cid:374)s we (cid:272)a(cid:374)"t regulate their diameter. Start regulating at bronchiole level with smooth muscle. Pleural sac (attaches lung to thoracic wall) with thin layer of water to make them stick together because of cohesion and adhesion. This allows for them to slide freely over each other instead of just sticking together. For the lung to be inflated, intra-pleural pressure must be less than the pressure within the lung. If it were greater it would want to collapse in on the lungs. Collapsed lung= no pressure gradient to reinflate cos air in cavity in higher than lungs. If the volume of a gas container doubles, the pressure is halved (boyle"s law- p1v1=p2v2) If there is air flow from a to b then the pressure in a is higher than the pressure in b. Intra-alveolar pressure decreases then comes back to atmospheric.
