Classroom and Laboratory Safety Signs
How Does Air Move Into and Out of Our Lungs?
Focus students’ attention by asking, Have you ever wondered how your lungs work? Next, ask the students how many times they breathe each minute and whether they breath faster when they run. Mention that humans normally breathe about 8-10 times per minute when at rest. When we exercise, our breathing rate increases to 15-20 breaths per minute. (You may consider having students count how many times they breathe in one minute while sitting still in their chair. They can compare this result to the number of breaths they take in one minute after jumping in place for 30 seconds.)
Stimulate a discussion about the lungs’ role in breathing. Ask, Do our lungs have their own muscles? Tell students that, surprisingly, our lungs have no muscles. The diaphragm (a thin layer of muscles at the base of the chest cavity) and rib muscles of the chest wall work for the lungs. By changing the size of the chest cavity, these muscles control whether air enters or exits the lungs.
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