ASU online, SHS 310 Lab # 1
View the following link: https://www.questacon.edu.au/outreach/programs/science-circus/videos/model-of-lung
If you like you
... [Show More] can make your own model of the respiratory system at home by following the directions in the video link.
You will need: scissors, an empty hard sided sports bottle, play-doh, a pencil, rubber band, a straw, and two medium to
large balloons. It is also possible to use a surgical glove instead of the balloon that goes on the bottom of the bottle. (It is
not necessary to make the model – you can just view the video – but some students appreciate the hands-on approach.)
Step 1: If using a balloon, cut off the neck of one balloon. If using a surgical glove, hold it by the cuff end, wrap a
rubber band tightly around the base of where the fingers begin. Stretch the balloon or the cuff of the glove over the
cut end of the bottle, so that about ½ to 3/4” extends around the lip of the bottle. Set aside.
Step 2: Insert the straw about 2” into the neck of the balloon. Use the rubber band to secure the top of the balloon so
that the straw stays in place. Be sure not to make it too tight.
Step 3: Roll the play-doh into a ball. Use the pencil to poke a hole through the middle, and remove the pencil. Insert
the end of the straw through the hole in the play-doh. Now, insert the balloon/straw unit (with the balloon end first)
through the narrowed neck opening of the bottle. Use the play-doh to form a seal around the perimeter of the bottle
opening and the straw. Voila! Your model is complete.
Answer the following questions regarding your lung model. The bottle represents your ribcage. The surgical glove you
placed on the bottom represents the diaphragm.
1. What does the intact balloon represent? Lung
2. What does the straw represent? Windpipe
Hold the model by the bottle. Using your other hand, hold the surgical glove (diaphragm) by the rubber band and pull it
down, away from the neck end of the bottle. What happens to the interior balloon? Circle the correct answers in the
following questions.
3. When you pull the diaphragm downward, what happens to the volume inside the bottle?
It increases / decreases.
The volume inside the bottle increases.
4. At the same time, what happens to the pressure inside this cavity of the bottle?
It increases / decreases. This pressure is called: positive / negative.
The pressure inside the cavity decreases. The pressure is negative.
5. Now, release the diaphragm. Try pulling in and out a few times. What happens to the interior balloon when you
release it? Why does the air flow out?
The interior balloon deflates. This is because the volume inside the bottle is decreasing and forcing the air out.
6. Let’s think about the air pressure in the balloon (alveolar pressure) compared to the atmosphere outside of the
balloon (atmospheric pressure). Before manipulating the diaphragm, what is the atmospheric pressure
compared to the alveolar pressure? positive / negative / equal
Before manipulating the diaphragm the atmospheric pressure is equal to the alveolar pressure. [Show Less]