SBI3U – Humberside C. I.
Full Name: ______________________________ Period: ______
Just Breathe Activity – Lung Worksheet
Wednesday, April 17, 2019
Learning Objectives:
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Describe the function of the respiratory system
Create a model of the lungs, and explain what happens when you inhale and exhale
Critically analyze changes that can occur in the respiratory system, and the effects each could have.
Materials:
-
2 L empty plastic bottle with the label pealed off – (students provide this the class before!!!)
2 plastic drinking straws
3 balloons
2-3 small rubber bands.
Tape
Plasticine/playdoh.
Scissors
Graduated cylinder
Background:
Have you ever been on a crowded subway or bus? You probably could not wait until you could get off so you
could move more freely. This is similar to the process that causes airflow into your lungs. The air molecules
are crowded outside (in the environment) and want to get into the lungs (inhalation) or they are crowded in the
lungs and want to get outside (exhalation).
When you inhale, your diaphragm contracts, and moves down, and your rib muscles pull up and out. This
creates a large space in your chest (thoracic) cavity. This decreases the pressure in your lungs, and air will flow
in moving from an area of high pressure and high concentration, to an area of low pressure and low
concentration. When your diaphragm and ribs relax, the thoracic cavity decreases, which increases the pressure
in the lungs, and forces the air out moving from an area of high pressure and concentration (now in the lungs) to
low concentration (now the outside environment).
Procedure
1. Using a pair of scissors cut off and discard the bottom third of the 2 L bottle. Fold a piece of tape over the bottom
of the 2 L bottle, to ensure there are no sharp edges.
2. Cut off the top of 1 balloon, and wrap it over the bottom of the bottle. Tape it so that it is securely in place, and
there are no holes anywhere (otherwise the model will not work, and you may be very sad). The bottle represents
your chest cavity, and the balloon is the diaphragm.
3. Take the two straws, and wrap the plasticine around each of them, about a third of the way down the straw. Then
combine them so they are close together.
4. On the other end of each straw, place about 2.5cm of the straw into the mouth of the balloon, then wrap an elastic
over the straw, to ensure that it stays where it is, and it stays sealed. Do this for both straws.
5. Take the balloons, and straws, and place them inside the 2L bottle wrapping the plasticine overtop the mouth of
the bottle.
6. About 4cm from the top of the straws, wrap your last elastic band around both straws to keep them together.
7. Visit https://www.teachengineering.org/activities/view/cub_human_lesson09_activity1 for a demonstration on
how to build your model.
8. Pull the diaphragm away from the lungs (down) observe what happens.
9. Slowly release or push the diaphragm back up to the lungs. Observe what happens.
10. Using a graduated cylinder, pour 10 mL of water into the left straw/balloon. Repeat steps 8 and 9 and observe.
Lab Assessment:
1. Describe what happens when you inhale (when you pull down on the bottom balloon in your
model).
2. Describe what happens when you exhale (when you push up or release the bottom balloon in
your model).
3. Explain what happens with your diaphragm and rib cage when you inhale and exhale.
4. Explain why this model is a good one to use to represent breathing. Explain why this model
is limited in its accurate depiction of breathing. Be concise and specific.
5. Why do you think some people can inhale more air at one time than others can?
6. What might happen if you punctured your chest cavity?
7. Having a cold or respiratory disease sometimes causes extra mucus to build up in the lungs.
You explored this effect by pouring water into one lung.
a. How did this “extra mucus” affect how much air could be inhaled?
b. How has the added water effected the lungs ability to perform correctly?
Lab Assessment: Answers
8. Describe what happens when you inhale (when you pull down on the bottom balloon in your
model).
The balloons (your lungs) inflate, take in more air, or get bigger. Technical Explanation: During inhalation, the
diaphragm contracts downward, and rib muscles pull upward, causing air to fill the lungs. (This increases the
volume of the thoracic cavity and decreases pressure in the lungs — the air will flow from the higher pressure
environment to lower pressure area in the lungs.)
9. Describe what happens when you exhale (when you push up or release the bottom balloon in
your model).
The balloons (your lungs) deflate, push out the air, or get smaller. Technical Explanation: During exhalation,
the diaphragm relaxes and the lungs contract which causes air to be pushed out from the lungs. (This decreases
the volume of the thoracic cavity and increases pressure in the lungs — the air will flow from the higher
pressure environment to lower pressure area outside the lungs.)
10.Explain what happens with your diaphragm and rib cage when you inhale and exhale.
When you inhale, Your diaphragm contracts, causing the dome shape to flatten. The intercostal muscles also
contract which lifts the rib cage up and out. This creates a large volume in the thoracic cavity, which drops the
pressure placed on the lungs. As the pressure decreases inside the lungs in comparison to outside the lungs, air
will move from an area of [high] (in the outside environment) to an area of [low] (inside the lungs). When you
exhale, the diaphragm relaxes and moves up to the dome shape, the intercostal muscles also relax, causing the
ribs to move back down and in. This creates a decrease in volume in the thoracic cavity, which increases the
pressure placed on the lungs. As the pressure increases in the lungs in comparison to outside air will move from
an area of [high] (inside the lung, to and area of [low] (outside the lung).
11.Explain why this model is a good one to use to represent breathing. Explain why this model
is limited in its accurate depiction of breathing. Be concise and specific.
Answers may vary but may include,
Good because: it represents the pressure changes between the lungs and outside, it shows
contraction of diaphragm.
Poor because: - diaphragm does not start dome shaped and inward to chest cavity. Is not
circular in shape, only shows increase in chest cavity at the diaphragm, does not show
intercostal muscles and expansion of rip cage. Does not show accurate splitting of trachea to
bronchi to bronchiole to alveoli.
12.Why do you think some people can inhale more air at one time than others can?
Larger chest cavity created – larger body size,
Better training – can expand chest cavity more compared to person of similar size, because they
are breathing more deeply.
13.What might happen if you punctured your chest cavity?
Lose your pressure gradient, no/no significant air movement.
14.Having a cold or respiratory disease sometimes causes extra mucus to build up in the lungs.
You explored this effect by pouring water into one lung.
a. How did this “extra mucus” affect how much air could be inhaled?
Decreased how much air could be inhaled.
b. How has the added water effected the lungs ability to perform correctly?
Level of expansion of the left balloon was significantly less. Had to pull the diaphragm a lot more to get the
balloon to fill more. Ie have to work harder to breathe more deeply, to acquire the same volume of air.