KINE 3012 Lecture Notes - Lecture 11: Pulmonary Artery, Gas Exchange, Venous Blood
11 Feb 2018
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Partial pressure gradients: gas exchange in pulmonary capillaries & tissue capillary levels involves passive diffusion. Partial pressures: 760mmhg is total atmospheric pressure at sea level. This is mixture of gases: b/t o2 is 21% of atmospheric, o2 exerts pressure of 160mmhg, greater the partial pressure of gas in liquid, more gas dissolved. Alveolar po2 & pco2: alveolar po2 (100mmhg) is lower than atmospheric po2 (160mmhg) b/c fresh inspired air is mixed with old air remaining in lungs & dead space, co2 produced by tissues is added to systematic capillaries. In pulmonary capillaries, co2 diffuses down its partial pressure gradient from blood to alveoli & removed from body through expiration: pco2= 40mmhg. This pulmonary blood is exposed to alveolar air which is high in o2. O2 diffuses from alveoli to blood until no gradient (100mmhg: blood entering pulmonary has pco2 of 46mmhg, alveola has pco2 of 40mmhg.
