PHGY 210 Lecture Notes - Lecture 8: Pulmonary Circulation, Pulmonary Artery, Alveolar Pressure
25 Jan 2017
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Toda(cid:455)"s le(cid:272)ture: co(cid:1006) , o(cid:1006) ho(cid:449) to get i(cid:374) a(cid:374)d out of (cid:271)lood diffusion. These are the partial pressure of co2 ando2 in air. In the alveoli ---this is the average number. In the very first breath, co2 , and o2 is same as outside. If the air mixes, and happen diffusion the average pco2 and po2 on picture. The gas diffuse through alveolar , capillary membrane. The transfer of gases across the alveolar-capillary membrane occurs by passive diffusion. This diffusion is very efficient in the lungs because of the huge surface area of the membrane and its extreme thinness. This diffusion is proportion to surface area. (the surface area of alveoli is like the tennis court enormous) and to px(partial) pressure gradient (more difference , diffuse more readily). It is inverse proportion to the thickness of alveoli, capillary membrane. (the membrane here is very thin) Diffusion is governed by fick"s law: diffusion rate is proportion surface area (50-100 m2)
