4E60.10 • Two-Balloon Model of the Alveoli

Location: Cabinet 10

Photo shoes the demonstration used at the University of Texas at Austin

---

Concepts Conveyed:

• The bigger balloon (partially inflated) has lower pressure than the smaller balloon - Boyle's Law: P1*V1=P2*V2
• Air flows from an area of high pressure to low pressure. Air flows from the smaller balloon to the bigger balloon.
• The model represents alveoli in the lungs; how they behave without surfactants (Respiratory Distress Syndrome). Bigger alveoli inflates while the smaller alveoli collapses, making it harder to breathe.

---

Instructions/Notes:

• Open the valve, turning the handle from perpendicular to parallel.
• Watch the result!

---

Demo Staff:

• Ensure valve is closed (perpendicular) before inflating balloons.
• Inflate both balloons with a balloon pump, with one being bigger than the other.
• Connect each balloon to each end of the valve without releasing air (this step is easier to do with 2 people).

Last updated on October 28, 2025