Breathe right

The classes at Mentari have been rather dull lately. The children's parents have been requesting more exam based classes. So I thought to make classes more fun, I thought what we need is more teaching aids and fun experiments. So last weekend I got one of the Form 2 students, one of the original pioneers to flip through the science text book and see if there are any experiments he'd like to do. One of the experiments he pointed out was the model of how the lungs work. I saw this as a very doable experiment. So what I did when I got back was search for any guides on making a lungs model. I found one guide on eHow but I couldn't get all the bits that the author used. So I improvised.

First of all, let us see the human respiratory system and see how it works. You have the mouth and nose cavity that converges at the trachea and that feeds the air to the two lungs via the bronchus. Under the chest cavity we have the diaphragm which plays a very important role in the respiratory system. 


The concept is simple. The chest cavity is at a certain pressure. As the lungs have no muscles to move them - they are basically blood filled balloons. To inhale, the diaphragm will move expand increasing the volume of the chest cavity. This creates a negative pressure in the chest cavity causing air to rush in filling the lungs. When we exhale, the diaphragm contracts creating a smaller volume in the chest cavity increasing the pressure in the chest cavity thus forcing the air out of the lungs. Simple right? So the key to breathing is the diaphragm.  

Right, now that the principles are clear, lets start on with our model. So in sci-art attack fashion, heres what you need to make a working model of the human lungs:

1) A Y-joint
2) 2 balloons
3) A flexible tube that fits into the Y-Joiny
4) A large (as large as you can get) plastic container.
5) Duct tape
6) Permanent marker pen and a art knife

Once you got all the stuff here's how you start making your own set of lungs!

1) At the bottom of the plastic container, trace around the perimeter of the piece of tube. This will be the hole for the Y joint. The position should be roughly at the middle of the bottom.

2) Cut out a hole slightly SMALLER than the circle you traced out just now. If you made any mistakes you can always enlarge the hole later.

I noticed that the plastic, being the brittle type cracks when I tried to cut it. The model needs to be air tight and cracks are not air tight. A simple fix is to stick some duct tape on both sides of the containers.

3) Slide in the Y joint through the hole like so, and attache the tube to the part of the Y-joint that pokes out of the container:

4) Put on the balloons. These are the lungs....

5) Put on the lid and stick on a piece of duct tape to make it into a handle and there you have it! the lung model is complete!

So this is how it works. Push the lid up to deflate the baloons: this is akin to breathing out.

To "Breathe in" pull the lid down and watch as the balloons which represent the lungs inflate

So there you have it. A simple, quick, working model of the lungs.

Something could probably to improve the diaphragm but for now I think it's good enough as one can already demonstrate how the lungs inflate and deflate by moving the diaphragm. Try it at home and you can use it to explain the respiratory system to your child/siblings/relatives/friends... ;) happy trying!