The Pathway for Oxygen: Tutorial Modelling on Oxygen Transport from Air to Mitochondrion
The ‘Pathway for Oxygen’ is captured in a set of models describing quantitative relationships between fluxes and driving forces for the flux of oxygen from the external air source to the mitochondrial sink at cytochrome oxidase. The intervening processes involve convection, membrane permeation, diffusion of free and heme-bound O2 and enzymatic reactions. While this system’s basic elements are simple: ventilation, alveolar gas exchange with blood, circulation of the blood, perfusion of an organ, uptake by tissue, and consumption by chemical reaction, integration of these pieces quickly becomes complex. This complexity led us to construct a tutorial on the ideas and principles; these first PathwayO2 models are simple but quantitative and cover: (1) a ‘one-alveolus lung’ with airway resistance, lung volume compliance, (2) bidirectional transport of solute gasses like O2 and CO2, (3) gas exchange between alveolar air and lung capillary blood, (4) gas solubility in blood, and circulation of blood through the capillary syncytium and back to the lung, and (5) blood-tissue gas exchange in capillaries. These open-source models are at Physiome.org and provide background for the many respiratory models there.
KeywordsMechanics of ventilation Oxygen transport in blood Blood-tissue oxygen exchange Oxidative phosphorylation
This research has been supported by NIH/BE-01973 and BE-8407, an HL 073598, NSF 0506477, and the VPR project GM094503. B. Jardine installed JSim and the models, which can be downloaded from www.physiome.org. The inspiration for the title comes from the pioneering works of Professor Ewald Weibel, University of Bern .
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