Model number

This model represents a bifurcating bronchiole with two alveolar compartments. The resistance to air flow is represented by resistors, and the compliance is repsented by a capacitor. It compares this model to Lutchen's model.


This model represents a bifurcating bronchiole with two alveoli. This model is driven by external forcing
 pressure (Ptp) as with positive pressure ventilation. There is no exchange between alveoli and blood,
and the fluid (air) is assumed to be incompressible. The pressure fluctuation at the mouth has a range
 of 5 mmHg to 9 mmHg. It includes a comparison with Lutchen's model for two cases: Case 1 and Case 6sine. 

Case 1 is for normal alveolar compartments that have synchronized flows and volume changes, and uses the
exponential pressure forcing function used in Lutchen's model. Case 6sine is for obstructive lung disease
affecting only one alveolar compartment, and uses a sinusoidal pressure forcing function.

Representative Electrical Circuit:fig 1



The forcing pressure at the mouth for Case 1: Exponential forcing:



The forcing pressure at the mouth for Case 6: Sinusoidal forcing:



Governing Equations in the BronchTwoAlv model:












Governing Equations in Lutchen's model:




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.

Download JSim model project file

Help running a JSim model.

 M.G. Levitsky, Pulmonary Physiology, Sixth Edition, McGraw Hill, 2003.
Key terms
lung compliance
RC circuit
lung mechanics
airflow in trachea
tidal volume
positive pressure ventilation

Please cite 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.

Model development and archiving support at provided by the following grants: NIH U01HL122199 Analyzing the Cardiac Power Grid, 09/15/2015 - 05/31/2020, NIH/NIBIB BE08407 Software Integration, JSim and SBW 6/1/09-5/31/13; 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.