Purpose: Students make a working model of a pair of lungs to see how the diaphragm, lungs, and trachea work together.
Materials:
- Plastic bottle with lid
- Straw
- Two rubber bands
- Two balloons
- Gum or modeling clay
- Cut off the bottom of the bottle
- Cut off the neck of the balloon
- Secure balloon over the open (cut) end of the bottle with a rubber band. (If bottle has a thin wall, glue a small piece of wood the width of the bottle inside the cut end of the bottle before attaching the balloon on the bottom. Using a stronger plastic bottle, such as a juice bottle, will eliminate the need for support.)*
- Make a small hole in the bottle lid (we used an Exacto knife)
- Insert the straw through the hole in the lid.
- Secure the other balloon onto the end of the straw using a rubber band.
- Screw the lid back onto the bottle and seal the hole around the straw with modeling clay OR with chewed gum (which works quite well, even if it is kind of gross).
- Your lung model is ready!
- Push in on the balloon on the bottom to deflate the balloon inside the bottle. Pull out on the balloon on the bottle to {slightly} inflate the balloon.
What’s happening?
In this model, the straw acts as the trachea, the balloon inside the bottle represents the lungs, and the balloon at the bottom acts as the diaphragm.
As we pull downward on the diaphragm-balloon (increasing the space inside the bottle), the air pressure inside the bottle decreases. This causes air to be sucked into the trachea-straw to inflate the lungs-balloon to fill up the empty space. This is what happens when we breathe in. When you release or push in on the diaphragm-balloon, the air pressure inside the bottle increases and pushes air out of the lungs-balloon and through the trachea-straw. This is what happens when we breathe out.
You can even feel the bottle breathing! How cool is that?!?
To learn more about how your lungs work, refer to Unit 7: Body Organs of the free ebook Classic Elementary Life Science. Be sure to also download the corresponding parent text!