BPK 205 Lecture 27: BPK 205 Notes Lecture 27

• School: Simon Fraser University
• Department: Biomedical Physio & Kines
• Course: BPK 205
• Professor: Nadine Wicks

Document Summary

Atmospheric air = 78% n2 + 21% o2 + 0. 033% co2. ; humid: pgas = (patm ph2o) x % of gas in atm. : po2 = 160 mmhg, pco2 = 0. 25 mmhg. Partial pressure remains relatively constant at rest: po2 = 100 mmhg, pco2 = 40 mmhg: hypoventilation: decrease po2, increase pco2 vice-versa for hyperventilation, discuss gas exchange across cellular barriers. O2 and co2 diffuse across alveolar epithelial cells and capillary endothelial cells. Fick"s law = diffusion rate (a x d x pgas)/t2; a = surface area, d = diffusion constant (membrane permeability), pgas = partial pressure gradient of the gas, t = diffusion distance. Partial pressure gradients in the respiratory system (normally reach equilibrium) Pulmonary: alveolar po2 > venous blood po2; alveolar pco2 < venous blood pco2. Systemic: arterial pco2 > tissue po2; arterial pco2 < tissue pco2: name some factors that affect gas exchange.