When we breathe inward (inhale), air from outside enters our airways and lungs. As demonstrated in the activity, “Breathing Machine,” breathing is a mechanical process, driven by changes in the volume of the chest cavity. The air taken in with a normal breath represents only part of the total amount of air the lungs can hold. Likewise, the amount of air normally breathed outward (exhaled) represents just a portion of the total amount of air that can be expelled.
The maximum amount of air that can be blown out of the lungs after taking a deep breath is known as vital lung capacity. But some air always remains in the lungs and airways.
Diseases of the respiratory system affect lung volumes and capacities in many different ways. Some diseases reduce the lungs’ vital capacity. Others cause changes in the amount of air held in the lungs after air is blown out forcefully.
Note: A spirometer is an apparatus for measuring the volume of air inhaled and expelled by the lungs. It is used to rule out different respiratory diseases and can help find the cause of shortness of breath, effects of contaminants on lung functions, effects of medication, and progress for disease treatment.
Keywords: air | lungs | diaphragm | breath | breathing | respiration | vital lung capacity | inhale | exhale | oxygen | carbon dioxide
- Moreno, N., Tharp, B., and Dresden, J. (2011) The Science of Air Teacher’s Guide. Baylor College of Medicine: Houston. ISBN: 978-1-888997-74-3
- Photo © Renato Ganoza. CC-BY-SA 2.0.
Your slide tray is being processed.
Funded by the following grant(s)
My Health My World: National Dissemination
Grant Number: 5R25ES009259
The Environment as a Context for Opportunities in Schools
Grant Number: 5R25ES010698, R25ES06932
Foundations for the Future: Capitalizing on Technology to Promote Equity, Access and Quality in Elementary Science Education