Glass lung (Casey Hayes)

Standards

• HS-LS1-3 - Plan and conduct an investigation to provide evidence that feedback mechanisms maintain homeostasis.

• HS-LS1-4 - Develop and use a model to illustrate the hierarchical organization of interacting systems provide a specific function in an organism.

Materials needed

• Bell jar apparatus (jar, glass tubing)

• Balloons

• Gatorade bottle

• Straws

• Glue

• Clay

Procedure

Students will first have the ability to study the respiratory system. Lectures will be given before hand and the pathway of the air is explained. Students can see that the lung is expanding, but why is that? are we pulling air into our lungs?

Students will cut the bottom of the plastic bottle and place balloons on the top of the bottle and on the bottom.

Explanation

The cavity inside the bell jar is airtight. As the diaphragm is pulled down, the volume of the cavity increases. This causes the pressure to decrease. Air rushes in to equalize the pressure, causing the balloons to inflate. As the diaphragm returns to it's original position, the volume of the cavity decreases. This causes an increase in pressure within the bell jar, the air rushes out of the balloons causing them to deflate. This is an excellent model to use with classes studying animal respiration or health applications.

Students have trouble seeing that the release of air from the bottle is strongly due to the vacuum that happens when the muscle increase the size of the chamber with allows the air to come into the body, this is all a reason why we can't breath through a tube that is too long when under water.

Questions

1. What does each part of the model represent?

   1. rubber sheeting = diaphragm

   2. balloons = lungs

   3. tube = glottis

   4. bell jar = chest cavity

2. Move the rubber sheeting down and describe what happens. Then, move the rubber sheeting back to it's original position and describe what happens.

   1. As the rubber sheeting is pulled down, the lungs inflate. As the rubber sheeting returns to its original position, the lungs deflate.

3. Repeat with the tube closed. Describe what happens.

   1. When the tube is closed, the lungs do not inflate as the rubber sheeting is moved down.

Everyday examples of the principles illustrated

Mechanisms of Breathing

Respiratory System

Concentration gradients

Photos

Movies

References

• Bell Jar Lung Model Wiki

• How Our Lungs Work

• Model of Lungs and Diaphragm

• Carolina Biological Supply Company