All web-HUMAN experiments, like their wet lab counterparts, involve changing one or more parameters and monitoring the response of relevant physiological variables. In the least complex design, only one parameter is changed. This is illustrated below via creating a high altitude challenge.
Students wish to simulate an ascent to the summit of Mount Mckinley (12,500 ft.), perhaps to compare the simulated data with actual data from a published experiment. The approximate barometric pressure at this height is 480 mmHg.
1) To begin
To set up HUMAN to run a physiological experiment, at the opening screen (see below)
- Start a Physiology Experiment (see above, middle)
- * always remember that if you wish to Save your experiment you must log in first (above, top)
This results in the typical opening web-HUMAN experiment screen seen in section 2 below.
The model is now ready for an experiment to be set up and then run.
2) To set up your experiment
HUMAN is now ready to be set up at high altitude for a 6 day experiment while tracking the respiratory and blood gas responses in its tables. The setup for this experiment is shown in the figure below and the steps involved in this setup are then described individually.
a) To change the barometric pressure (BAROP) from sea level value (760 mmHg) to 12,500 ft. value (480 mmHg).
Under Change Variable scroll down to BAROP and enter the new desired value (480).
b) To change the output table columns to read out ventilation and blood gas variables.
Under View Output: (first row) mouse columns 1 (AP) through 6 (EXER) to obtain output variable names for
|HUMAN Variable||Physiologic variable*|
|PO2A||Alveolar partial pressure O2 (mmHg)|
|PCO2A||Alveolar partial pressure CO2 (mmHg)|
|PH||Arterial blood pH|
|VENT||Lung ventilation (Liters/min.)|
|BICARB||Plasma bicarbonate (meq./Liter)|
|BAROP||Barometric pressure (mmHg)|
c) To set up the graph to plot all 6 of these variables (be certain your browser popup blocking is off!)
1) Under View Output as: (upper left, 2nd row)
change each variable to as: graph from its default as:text (see VENT as an example)
(This will result in output both as a Table and as a Graph)
2) Under Graph Style (lower right) simply retain the default choices of
- a normalized plot (values will be shown as change from baseline control values) and
- one graph (all 6 values will be shown on one single plot)
d) To setup to gather data for 6 days at 12 hour intervals
Under Run Experiment
- this runs the experiment resulting in a tabular and a graphic output window.
- Click on the Tabular window to bring it to the foreground as shown in the "Output From Web-HUMAN Physiology Simulation" below.
3) The output of your experiment
- The output of the high altitude experiment, beginning on Day 1 at 12:10 a.m. (column #1)
Click on the graph to bring it to the foreground. It appears as shown below.
The graphic output (above) also clearly illustrates each of these trends.
Note, for example, the large increase in Ventilation (purple squares top) and the marked almost mirror image decrease in Arterial (blood) CO2 tension (green x, bottom).
4) Some other possibilities
a) observations in this data- the beginnings of a compensatory kidney-induced ('metabolic') acidosis
b) observations by setting up new tables (i.e. observing other variables)
- To peruse all available variables, use Help info on: <choose> for any variable and on the newly appeared Help screen select View summary of all variables.
- select appropriate variables to track the developing polycythemia, increased hemoglobin, increased red cell production and increased blood viscosity.
c) new variations on the experimental design
- can the high altitude hypoxia be fully relieved by breathing 100% O2 (FO2AT) [fraction of O2 in atmosphere]?
- how compromised is the model's exercise endurance on Mckinley as compared to sea level (adjust EXER and XERMIN, testing in each environment at comparable exercise levels).