KINE 3012 Lecture Notes - Lecture 12: Tidal Volume, Venous Blood, Cellular Respiration
11 Feb 2018
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Other factors: diffusion rate of gas depends on surface area & thickness of membrane. Gas exchange across systematic capillaries: o2 & co2 moves b/t systematic capillary blood & tissue cells by simple passive diffusion, arterial po2 & pco2 is same as alveolar. Po2 & pco2 gradient across systemic capillaries: cells consume o2 & produce co2 through oxidative metabolism, oxygen diffuses down gradient from systematic capillary blood (100mmhg) into adjacent cells (40mmhg) until equilibrium reached. Venous blood leaving systematic is 40mmhg: co2 diffused out of cell (46mmhg) to capillary blood (40mmhg). Diffusion until blood pco2 = tissue pco2: more active the tissue cells, greater cell metabolism, larger blood-cell pressure gradients & more ventilation. Net diffusion of o2 & co2 b/t alveoli & tissues: o2: alveoli blood tissue, co2: tissue blood alveoli, once equilibrated, the venous blood has pressures of tissues cells. Blood o2 & hemoglobin: oxygen present in blood in 2 forms, physically dissolved in blood, chemically bond to hemoglobin.
