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Static Relationships    Elastic properties of the lung, chest wall, and total respiratory system
Dynamic Relationships I    Effects of lung compliance and airway resistance on tidal volume development
Work of Breathing    Oxygen cost of elastic, resistive, and total work during inspiration
Dynamic Relationships II    Respiratory dynamics of the total respiratory system
Alveolar Gas Exchange    Gas exchange between atmosphere and alveolar reservoir
O2 and CO2 Dissociation Curves    Interrelationships between the O2 and CO2 dissociation curves
Exchange from Atmosphere to Tissues    Influence of alveolar ventilation, cardiac output, and anatomic shunt flow on arterial blood composition and gas exchange at the tissues 
Gas Exchange in a Single Alveolus    Effects of ventilation-perfusion ratio and inspired gas composition on exchange in a single exchange unit
The Non-Uniform Lung     Gas exchange from atmosphere to tissues with VA/Q mismatching in the lung
Overall Gas Exchange    Gas exchange from atmosphere to tissues with VA/Q mismatching and a true shunt
Acid-Base Balance    Acid-base balance from a Base Excess viewpoint
•  Series of 11 Simulations in Respiratory Physiology
•  Online Help Manual Included
•  Designed for use in student laboratory and group discussion environments
•  Pictorial outputs designed to provide conceptual aid, show where variable values are measured, or illustrate the model and how it is solved
•  Compare data from up to 7 ‘experiments’
•  Download at no charge
Simulations in Physiology: The Respiratory System is a series of eleven simulated clinical and laboratory situations designed to provide students with thinking tools for examining their understanding of respiratory physiology.  Each simulation deals with a limited number of concepts relevant to the physiology of the respiratory system.  Each simulation requires the student to enter values defining an experiment or situation.  Calculated values consistent with the problem definitions are then returned.  It should be clear that these simulations are not intended as primary instruction tools. Four general areas of study are included. The simulations in each area of study build in complexity.  Hence, models appearing later in an area assume some familiarity with the concepts covered in earlier models. 
This series of three simulations begins with, Alveolar Gas Exchange, a model of gas movement from the atmosphere to the alveoli. Alveolar Gas Exchange allows manipulation of the factors that determine the levels of oxygen and carbon dioxide in the alveolar compartment. The second simulation in this series, Oxygen and Carbon Dioxide Dissociation Curves, provides a means of examining transport of oxygen and carbon dioxide in the blood. The next program, Gas Exchange from the Atmosphere to the Tissues, continues the development of general gas exchange by considering a one compartment lung with a tissue bed. Thus, factors affecting arterial blood gas composition and mixed venous blood gas composition can be examined.
This series of four simulations begins with examining the respiratory system under static (no gas flow) conditions in Static Relationships. Static Relationships provides a means of manipulating the factors that determine the elastic properties (recoil) of the total respiratory apparatus. The second model, Dynamic Relationships I, adds factors that influence gas flow and allows the student to manipulate variables that determine the tidal volume. Dynamic Relationships I views the system from the intrapleural space to the atmosphere. A subsequent model, Dynamic Relationships II, allows the student to examine determinants of a tidal volume from the respiratory muscles to the atmosphere. In doing so, Dynamic Relationships II allows the student to examine this process at a higher level of complexity. The fourth model, Work of Breathing, provides a means of examining the work of breathing in terms of the oxygen cost of inspiration.
These three simulations focus on appropriate matching of ventilation to blood flow within the lung. In Gas Exchange in a Single Alveolus, students can examine the influence of variations in blood flow and ventilation in a single gas exchange unit. The scope of the investigation is expanded to a two-compartment lung with a tissue bed in The Non-Uniform Lung, and, finally, to a two-compartment lung with the possibility of anatomic shunt in Overall Gas Exchange.
The final model in the series, Acid-Base Balance, allows the student to examine buffer systems involved in maintaining extracellular hydrogen ion concentration relatively constant. This simulation approaches the issue from the viewpoint of adding or removing hydrogen ions to the system.
For each model you would like to download, click on its name.  In the “Save as...” dialog box,  choose the location on your computer where you would like the setup file to be copied (copying to the desktop is often the easiest option for finding the file).  Once the file has finished downloading, double click the icon on your computer (Remember, the icon will be located in the place you designated in the “Save as...” dialog box).  The file will self-extract and install.  You will find the program under your Start Menu, Programs, Respiratory Simulations.  At this point, you can delete the downloaded file on your desktop.  Please consult the online help manual for instructions on using the simulations. 
Download Static Relationships	(~2.1 MB) Download Dynamic Relationships I	(~2.1 MB) Download Dynamic Relationships II	(~2.1 MB) Download Work of Breathing	(~2.1 MB) Download Alveolar Gas Exchange	(~2.1 MB) Download Oxygen and Carbon Dioxide Dissociation Curves	(~2.1 MB) Download Gas Exchange from the Atmosphere to the Tissue  (~2.1 MB) Download Exchange in a Single Alveolus	(~2.1 MB) Download The Non-Uniform Lung  (~2.1 MB) Download Overall Gas Exchange  (~2.1 MB) Download Acid-Base Balance  (~2.1 MB) Return to Educational Materials Who Are We? How Can We Help You? What Do We Do? What is PERC?
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