The lungs are an essential organ for all mammals. Lungs have several features which make them perfect for exchanging gases.
- a very large surface area, thanks to a network of small tubes and tiny air sacs called alveoli.
- they are moist
- and have a good blood supply
Today we’re going to find out how lungs work by making a lung model.
The lungs are part of our breathing system, which has two functions:
- ventilation – the movement of air into and out of the lungs
- gas exchange – gases are exchanged between tiny sacs called alveoli and the blood.
Under the lungs is the diaphragm, a muscular sheet separating the lungs from the abdomen. The diaphragm moves up and down to increase the space in the chest like the balloon at the bottom of the model.
To make a model lung you’ll need
- A plastic bottle
- A straw
- An elastic band
- Two balloons
- Play dough
The bottle acts like the chest cavity, the balloon at the bottom is like the diaphragm and the balloon in the centre is like a lung.
Instructions for making a model lung
- Carefully cut the bottle roughly in half. Ask an adult to help. Discard the bottom half.
2. Tie a knot in one end of one balloon and cut off the opposite end.
3. Stretch the balloon around the bottom of your plastic bottle.
4. Place a straw in the neck of the other balloon and secure it tightly with the elastic band but not so much that you crush the straw. The air must flow through, so test it with a little blow through the straw to see if the balloon inflates.
5. Put the straw and the balloon into the neck of the bottle and secure them with the play dough to make a seal around the bottle – make sure that again, you don’t crush the straw, but air can flow through.
Hold the bottle and pull the knot of the balloon at the bottom. What happens?
You should find that the balloon inside the bottle inflates, and as you let go the balloon deflates.
Why does this happen?
As the knotted balloon is pulled it creates more space inside the bottle. Air then comes down the straw and fills the balloon with air to fill the space! This is like breathing in.
When you let go of the knot the space no longer exists, so the air from the balloon is expelled making it deflate.
Inside the lungs is a network of tubes which allow air to pass through. Air is warmed, moistened and filtered as it travels through the mouth and nasal passages. It then passes through a network of tubes, eventually reaching tiny sacs called alveoli which is where gas exchange occurs.
How do lungs work?
This lung model demonstrates how the lungs work. Air is taken in through the mouth and nose, passes down the windpipe and into the lungs. The diaphragm at the bottom of our chest moves down to create more space. As we breathe out the diaphragm raises again. The knotted balloon represents the diaphragm and the balloon inside the container represents a lung. That’s how lungs work!!
More ideas for learning about the lungs
Create a labelled diagram of the gas exchange system.
Use balloons to make a very simple model of the lungs.
More human body science ideas
Create and build a DNA model from candy
Try this super simple heart rate investigation.
Make your own stethoscope with a cardboard tube, tape and a funnel.
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If you enjoyed this activity do check out my other easy science investigations for kids of all ages.
Last Updated on October 17, 2022 by Emma Vanstone