Which part of the living system did you change?
Labs / Biology
Alveolar Gas Exchange
A single air sac sits above a capillary of flowing red blood cells. Oxygen and carbon dioxide slip across the thin membrane between them, each moving from where its pressure is high to where it is low. Change how you breathe, climb to altitude, or thicken the membrane and watch the blood's oxygen saturation respond in real time.
Labs / Biology / Alveolar Gas Exchange
Alveolar Gas Exchange
A single air sac sits above a capillary of flowing red blood cells. Oxygen and carbon dioxide slip across the thin membrane between them, each moving from where its pressure is high to where it is low. Change how you breathe, climb to altitude, or thicken the membrane and watch the blood's oxygen saturation respond in real time.
Why it matters
Why explore this?
Living systems are connected and constantly changing. This model makes one biological process visible so you can test how its parts affect one another.
Explore
Try the model
SaO₂ 97%PaCO₂ 40 mmHgO₂ in 250 mL/minCO₂ out 200 mL/min
Investigate
Questions to test
Predict first, try it in the model, then use what you observe to answer.
What to try
- Climb to 5 km. Why does the blood leave the lung less than fully saturated even though the air is still 21% oxygen?
- Breathe fast and deep. What happens to PaCO₂ — and could you actually blow off too much?
- Thicken the membrane to model emphysema. Which gas struggles first to cross — O₂ or CO₂?
- Switch to Exercise. The blood now races past the membrane — does it still have time to fully load oxygen?
- Combine high altitude with a thick membrane. How low can you push the O₂ saturation, and why do the two problems stack?
Explain
Make sense of what happened
Explain the process as a chain: a change happens, the system responds, and that response affects what happens next. Use an observation from the model as evidence.
Check
Before you leave
How did the system respond?
How would you explain that response?
If you can answer all three using evidence from the model, you understand the main idea. If not, return to Explore and change one setting at a time.