Q1.
What do the balloons in the model mentioned in Fig. 9.9 represent? What does the rubber sheet represent?
Answer
In this model, the balloons represent the lungs and the rubber sheet represents the diaphragm.
| Part of the model | Part of the body it represents |
|---|---|
| Two balloons | The two lungs |
| Thin rubber sheet at the base | The diaphragm |
| Y-shaped hollow tube | The windpipe and its two branches |
| Wide plastic bottle | The chest cavity, enclosed by the rib cage |
Why it happens: pulling the sheet down copies the diaphragm moving downwards during inhalation, which increases the space inside the chest so that air enters the lungs. Releasing it copies the diaphragm moving upwards during exhalation, which reduces the space and pushes air out.
Tip: the model has one limitation — the bottle is rigid, so it cannot show the ribs moving up and outwards. In the real chest, the ribs move as well as the diaphragm.