You will need:

- a plastic PET bottle.
- balloon
-sticky tape
-plastic funnel.

The lungs contain elastic tissue and the way they function can be demonstrated by building a simple model as shown above.

Step 1 Tape a party balloon to the end of a funnel.
Step 2 Place the balloon inside a PET bottle and secure the funnel to the bottle using sticky tape as shown in the picture above. See the video of the model on the right.

Squeezing the bottle mimics the movement of the diaphragm heart shoulder muscles wind pipe

When the bottle is squeezed low pressure high pressure is created inside the bottle which deflates inflates the balloon.

When the bottle expands low pressure high pressure is created inside the bottle that pushes air out of sucks air in the balloon.

True of False.
When playing with the model it is obvious that

The lungs have muscle that help them inflate and deflate. False True

As the chest wall expands, low air pressure is created inside the lungs that sucks air in. False True

To expel air from the lungs the diaphragm must relax. False True

To inhale, the diaphragm must contract and the rib muscles relax to increase the volume of the chest cavity. False True