Introduction: Make a Human Lung Model

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Air! It is what keeps us alive, keeps us breathing! Some of you may know that plants help make oxygen, and oxygen is the air we breathe, but how do we breathe? How do our cells get oxygen? Part of the reason is our respiratory system, and our lungs! For this project we will be learning about how our lungs work by making a model of the lungs that include the diaphragm.

How do our lungs work?

When we breathe, our lungs bring in fresh oxygen for our body and remove carbon and dioxide and other waste gases our bodies don’t need.

When we inhale, or breathe in, we use the muscles in our rib cage, especially the muscle called the diaphragm.

To get the oxygen your body needs, you inhale air through your mouth and nose and air passes through the throat into the trachea. Also called the windpipe.

The trachea divides into the left and right bronchi, like a branch, each bronchus divides again and again, becoming narrower and narrower. Kind of like tree branches.

Your smallest airways end in the alveoli, al·vee·uh·lai, small, thin air sacs that are arranged in clusters. Alveoli are an important part of the respiratory system. It is their job to exchange oxygen and carbon dioxide molecules to and from the bloodstream and thus to and from our cells!


● Plastic bottle with screw top cap

● Straws x 2-3

● Rubber Bands x 2

● Tape

● Balloons x 2

● Plastic Wrap

● Scissors


Step 1: ​Cut the Bottom Off Your Plastic Bottle

When you choose your bottle, make sure it is big enough to hold the size of balloons you have, and that the bottle is somewhat sturdy. I used a 2 liter soda bottle, it was just sturdy enough and as I had bigger balloons, it was better to be wider than a smaller bottle.

Pierce your plastic bottle. I used an exacto knife for the initial pierce. Then you can cut around the bottom of your bottle with either your scissors or continue using an exacto knife (ONLY AN ADULT SHOULD USE THE EXACTO KNIFE).

Remember, you only need to cut off the bottom, to make sure you will have enough room length wise for the straw as well.

Step 2: Carefully Cut/screw a Hole in Your Bottle Cap

Carefully using your exacto knife (ONLY AN ADULT SHOULD USE THE EXACTO KNIFE), cut a hold roughly the size of your straw. This can be accomplished by cutting an X engraving on the bottom and on the top, then finding the center of your X pierce with your knife in a screw-like motion until it goes through the cap. Repeat this until you have a nice small circle.

(If this ends up being too challenging, feel free to avoid using a twist cap and use modeling clay or playdough on the future step, when adhering the cap to the straw.

Step 3: ​Cut Your Straws to Be Your Windpipe

Use 2 or 3 straws for this step. First, if you have bending straws, cut them slightly after the bend in the straw, so you are still able to bend it. If not cut the about 3 inches off one side. Keep one of the longer lengths of the straws to do the following: Take your scissors and cut so you cut the straw at an angle on both sides to create a point. Once you have the point use your scissors and put one blade inside the staw and cut about 1 to 1.5 inch up. Repeat for the other side.

You should now have a slit to place the smaller straw pieces into. Make sure the smaller pieces fit the way you want and that air can be blown through one and go out of both ends.

Finally lightly tape the pieces together so there is no excess air able to go through the slits. Remember not too tight, or it will constrict air flow.

This structure will be our trachea, or windpipe, that brings air into the body. It divides into the left and right bronchi continuing the air travel into our lungs.

Step 4: Prepare Your Balloons to Be Your Lungs (optional)

Take your two balloons and use your scissors to cut the top of the ballow off. This is an optional step, I found it easier to attach the balloon this way, and more air was able to flow into them this way as well.

The balloons are the part of the model that make up the outer part of your lungs

Step 5: Attach Your Lungs to Your Windpipe

Next, take one balloon and put one side of your windpipe (straw) into the balloon and, using tape, lightly wrap the balloon around the straw making sure there is no obstruction to air flow. Repeat with the other balloon and side of the windpipe.

This way air will be able to travel safely though each bronchus and into the alveoli sacs.

Step 6: ​Put Your Lungs Into Your Bottle

Now you are ready to insert your lungs into your bottle. You will want to do so by inserting your lungs straw side up into the bottle. Now take your lid and put the top of your windpipe (straw) through the hole. If you have difficulty, try folding the top of the straw to squeeze it into the lid. Once your straw is through the lid screw the lid back onto the bottle and lightly tape around the hole so there isn’t excess air.

(If you choose to not make a hole in your lid, instead of using a lid, cover the straw and mouth of the bottle with clay or playdough so it is airtight.)

This will make something similar to a vacuum chamber.

Step 7: ​Prepare Your Plastic Wrap to Be Your Diaphragm


your plastic wrap to be your diaphragm

Cut a square of plastic wrap large enough to cover the bottom of your bottle. Then, using your rubber bands, secure the plastic wrap around your bottle. I used two rubber bands, one when to initially secure and the other to secure the excess plastic.

In our model this plastic wrap represents the diaphragm. Our diaphragm tightness and flattens allowing us to suck air into our lungs. To breath out, or exhale, our diaphragm and rib cage muscles relax, letting the air out of our lungs.

Step 8: ​ Attach a Tab to Help Control Your Diaphragm

Use extra tape or an extra rubber band and tape to create a pull tab for your diaphragm. Simply, fold the tape over on itself, so it creates a rope. Then tape then rope to the bottom of your model.

Step 9: Make and Observe Your Lungs Inhale and Exhale!

Pull your plastic wrap down to contract the diaphragm and make your lungs inhale the air. Relax the plastic wrap quickly or slowly and see what happens!

The air is exhaled!

You made a model of the lungs with a diaphragm!