HbO.CO2.H.DPG.T
HbO2CO2H: Oxyhemoglobin (HbO2) binding at varied O2, CO2, and pH.
Model number: 0278
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Description
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Oxygen binds to all 4 sites of hemoglobin's heme sites, but the affinities
are cooperative (meaning that affinity increases for each
site filled. Further the affinities are influenced by pH and by the binding of
CO2 to the protein's side chains. This model assumes equilibrium binding, i.e.
instantaneous binding in accord with the relevant concentration levels. Thus
although each reaction might be described by an on and an off reaction, it
assumes rather that this reaction goes to equilibrium at each of the 4 sites in
succession. The pO2 at 50% saturation, i.e. 50% of Hb bound to O2, is the pO2
at which the molar concentration of O2 equals an effective Kd. Here, the pO2
is run through a wide range of concentrations, but there is no direct
calculation of the Kd or p50. It equals 1/KHbO2 only at 50% saturation point,
not at other pO2's. The p50 is 26.8 mmHg at pCO2 40, pH 7.24. The model has
the particular virtue of accounting for pCO2 and pH, and of being expressed as
a Hill-type expression, though the expression's key modifier is the variable
KHbO2, the apparent Hill coefficient for O2. KHbO2 is an invertible expression
and therefore allows great computational convenience during calculations of
transients and intracapillary gradients. The parent model (Dash and
Bassingthwaighte 2004) accounts also for the effect of 2,3-bisphosphoglycerate
and temperature.
Additional description and FIGURE notes as needed here...
Equations
The equations for this model may be viewed by running the JSim model applet and clicking on the Source tab at the bottom left of JSim's Run Time graphical user interface. The equations are written in JSim's Mathematical Modeling Language (MML). See the Introduction to MML and the MML Reference Manual. Additional documentation for MML can be found by using the search option at the Physiome home page.
Example equations, remove as needed:
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References
Dash RK and Bassingthwaighte JB. Blood HbO2 and HbCO2 dissociation curves at varied O2, CO2, pH, 2,3-DPG and temperature levels. Ann Biomed Eng 32: 1676-1693, 2004. Dash RK, Li Z, and Bassingthwaighte JB. Simultaneous blood-tissue exchange of oxygen, carbon dioxide, bicarbonate, and hydrogen ion. Ann Biomed Eng 34: 1129-1148, 2006. Carlson BE, Anderson JC Raymond GM, Dash RK, and BAssingthwaighte JB. Modeling oxygen and carbon dioxide transport and exchange using a closed loop circulatory system. ISOTT2006, 101-108, 2006
Related Models
None.
Key Terms
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Model History
Get Model history in CVS.Acknowledgements
Please cite www.physiome.org in any publication for which this software is used and send one reprint to the address given below:
The National Simulation Resource, Director J. B. Bassingthwaighte, Department of Bioengineering, University of Washington, Seattle WA 98195-5061.
[This page was last modified 09Feb10, 10:19 am.]
Model development and archiving support at physiome.org provided by the following grants: NIH/NHLBI T15 HL88516-01 Modeling for Heart, Lung and Blood: From Cell to Organ, 4/1/07-3/31/11; NSF BES-0506477 Adaptive Multi-Scale Model Simulation, 8/15/05-7/31/08; NIH/NHLBI R01 HL073598 Core 3: 3D Imaging and Computer Modeling of the Respiratory Tract, 9/1/04-8/31/09; as well as prior support from NIH/NCRR P41 RR01243 Simulation Resource in Circulatory Mass Transport and Exchange, 12/1/1980-11/30/01 and NIH/NIBIB R01 EB001973 JSim: A Simulation Analysis Platform, 3/1/02-2/28/07.
