Lesson: Breathe In, Breathe OutContributed by: Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder
Educational Standards :
Pre-Req Knowledge (Return to Contents)
Some basic knowledge of the parts of the human respiratory system.
Learning Objectives (Return to Contents)
After this lesson, students should be able to:
Introduction/Motivation (Return to Contents)
When was the last time you thought about your respiratory system? When was the last time you coughed, sneezed or hiccupped? Every time you do one of these things, it should remind you of your respiratory system. From where does a cough come? A sneeze? What about a hiccup? A cough is the way your respiratory system clears the airway. A sneeze is caused by an irritation in the upper airway. A hiccup is a spasm of the diaphragm. The respiratory system is an internal system that is constantly exposed to the outside environment. Every time we breathe in, we take in what is in the air around us, including dust, bacteria, pollen, smoke and chemicals. Our respiratory systems help us filter out these particles before they enter our bloodstreams.
Does the respiratory system always work? Many things we breathe in can harm and even destroy the respiratory system. People who suffer from asthma often cough and find it hard to breathe. Lung cancer, especially common among people who smoke, can kill people. Tuberculosis (TB), a disease caused by bacteria, can destroy a person's lungs. TB is highly contagious, and affects cats and other animals as well as people. Most people, at some point, experience minor and temporary respiratory problems in the form of a sore throat, cough or bronchitis.
Asthma is experienced when the inside walls of your airways become swollen and sensitive. Then, if something irritating enters your airways, they narrow, restricting oxygen from reaching your lungs. In a severe asthma attack, the airways can close so much that your vital organs do not get enough oxygen. Chemical engineers design medicines and their delivery systems, such as inhalers, to help people breathe better. Some medicines are for quick-relief, to stop asthma symptoms when they happen and others are long-term control medicines, to prevent symptoms.
Lung transplants are necessary when lungs are too damaged to work anymore and no other alternative treatments exist. In 2005, about 3,500 people in the U.S. were waiting for lung transplants, and only 1,000 of them received transplants. Hospitals use machines designed by engineers that do the work of the heart and lungs, by pumping blood and exchanging oxygen outside the body to help a patient recover from a case of lung failure from infection or trauma. Engineers are working on devices that could filter and clean oxygen inside the body, similar to the way working lungs do. These artificial lungs would be small (about the size of a soda can) and implanted in patients'chests to help them stay alive longer while waiting for lung transplants.
To design machines and medicines to help people whose respiratory systems are not fully functioning, engineers must thoroughly understand the human respiratory process. Some biomedical, electrical and mechanical engineers develop pulmonary function testing and diagnostic equipment (spirometers, see Figure 1), as well as artificial lungs that help seriously ill patients breathe while fighting off infections.
Lesson Background & Concepts for Teachers (Return to Contents)
The Respiratory System
The respiratory system is an organ system in the body primarily used for gas exchange. In most four-legged animals, the respiratory system generally includes tubes, called the bronchi, which carry air to the lungs, where gas is exchanged. A diaphragm pulls air in and pushes it out.
In humans and other mammals, the respiratory system consists of the airways, the lungs and the respiratory muscles that move air into and out of the body (see Figure 2). In the alveoli of the lungs, oxygen and carbon dioxide molecules are exchanged between the gaseous environment in the lungs and the blood. The respiratory system facilitates the movement of oxygen to the blood (oxygenation), while removing carbon dioxide and other gaseous wastes from circulation.
The respiratory system provides energy to the body by delivering oxygen to the lungs, from where it travels through the blood to the cells. The respiratory system also removes waste by-products of respiration and various cell functions, such as carbon dioxide. The respiratory system is connected to the circulatory system.
Inhalation is driven primarily by the diaphragm. When the diaphragm contracts, the ribcage expands and the contents of the abdomen are moved downward. This movement results in a larger volume inside the chest cavity, which causes a decrease in pressure. As the pressure in the chest falls, air moves into the conducting zone, where it is filtered, warmed and humidified — all by different parts of the respiratory system — as it flows to the lungs. By contrast, exhalation is typically a passive process. The lungs have a natural elasticity, or ability to stretch. As the lungs recoil from the stretch of inhalation, air flows back out until the pressures in the chest and the atmosphere become equal.
After air inhalation, gas exchange occurs in the alveoli, which are the tiny sacs in the lungs at which gas exchange takes place. Aveoli walls are extremely thin and permeable to gases, so gases flow easily between them. The alveoli are lined with pulmonary capillaries, the walls of which are also thin enough to permit gas exchange. Oxygen diffuses from the air in the alveoli to the blood in the pulmonary capillaries. At the same time, carbon dioxide diffuses in the opposite direction, from the blood in the capillary to the air in the alveoli. At this point, the pulmonary blood is oxygen-rich, and the lungs are holding carbon dioxide. Exhalation follows, ridding the body of the carbon dioxide, and completing the respiration cycle.
See the Vocabulary/Definitions section for information on additional, important components of the respiratory system, and their functions.
Currently, engineers are working to develop small artificial lungs that can be implanted into the chest. The intent is for this technology to efficiently carry on the gas exchange function of a person's lungs during recovery from injury or illness, or until donor lungs are available for transplantation. Hospitals currently use a technology called ECMO, or extracorporeal membrane oxygenation. ECMO machines take over the functions of the lungs and heart, pumping blood and exchanging carbon dioxide for oxygen in a machine outside the body. The drawbacks to using this external type of machine include the mechanical pumps, which may damage red blood cells. These new artificial lungs would use the heart as the pump and be implanted into the chest to eliminate some of the current problems. While these new technologies are not a long-term solution for severe lung damage, they may give patients enough support until donor lungs become available.
Vocabulary/Definitions (Return to Contents)
Associated Activities (Return to Contents)
Lesson Closure (Return to Contents)
The respiratory system is an incredibly important system in our bodies. Understanding its function is critical to keeping our bodies healthy and responsive to situations and medical problems that we encounter. Understanding how air pollution and contaminants in the air that we breathe directly affect the respiratory system and lungs is also critical in understanding how to protect and prolong the life and functioning of the respiratory system.
Engineers work with doctors to come up with medical testing and treatment solutions to issues affecting the respiratory system, as well as monitoring and improving the quality of the air that is inhaled by it. Many types of engineers contribute to projects that improve the health of people's respiratory systems. Chemical engineers design medicines that help people breathe better. Other engineers design the medicine delivery systems, whether they are inhalers, syringes or pills or capsules. Biomedical, electrical and mechanical engineers develop pulmonary function testing and screening equipment, as well as artificial lungs that help ill patients breathe and filter oxygen while fighting off infections.
Assessment (Return to Contents)
Think/Pair/Share: Have students ask and answer the following questions with a partner:
Scenario/Question: Provide students with the following scenario/question, asking them to write a brief and clear description, accurately using respiratory system terms:
Lesson Summary Assessment
Discussion: If you were an engineer creating a set of artificial lungs, what design considerations would be important to think about? (With this open-ended design question, the teacher is looking for evidence that students are thinking about the parts of the respiratory system, its function, and what affects it. Example responses might include: Lungs should be able to stretch, lungs should be able to fit in the chest cavity, lungs should be able to carry out gas exchange, lungs should be supple, must know the person's health history, how much more the person might grow, location where the person lives and breathes, etc.)
Lesson Extension Activities (Return to Contents)
Have students research engineering advancements in artificial lungs. How has this technology increased the rate of survival of people who have damaged lungs?
Asthma is the leading serious chronic illness of U.S. children. Have students learn more about asthma, its symptoms and triggers. Most students know someone with asthma. Direct students to research the medicines and inhalers engineers have developed to help manage asthma attacks.
Lung disease is one of the top three diseases causing death in the U.S., and lung disease and respiratory problems are the leading cause of death of infants under the age of one. Have students learn more about lung disease, its causes, symptoms and treatments. Assign students to create an informational brochure for their school, family or community outlining the risks and what can be done to reduce one's chances of lung disease.
Additional Multimedia Support (Return to Contents)
See a good overall respiratory system diagram with parts identified and described (interactive flash presentation) at the American Lung Association's Search LungUSA website: http://www.lungusa.org/your-lungs/how-lungs-work/
References (Return to Contents)
Asthma. American Lung Association. Accessed December 16, 2008. http://www.lungusa.org/lung-disease/asthma/
Dictionary.com. Lexico Publishing Group, LLC. Accessed December 16, 2008. (Source of some vocabulary definitions, with some adaptation) http://www.dictionary.com
Downs, Martin F. Artificial Lung Closer to Clinical Trial. Reviewed November 25, 2002. WebMD, Inc. Accessed December 16, 2008. http://www.webmd.com/healthy-aging/features/artificial-lung-closer-to-clinical-trial
How Lungs Work, The Respiratory System. American Lung Association. Accessed November 3, 2010. (interactive flash presentation shows diagram and description of parts of human respiratory system, titled, "Would You Like to See How I Breathe?"; scroll down the page to find it) http://www.lungusa.org/your-lungs/how-lungs-work/
Lamb, Annette and Johnson, Larry. Respiratory System: The Basics. Last updated December 2001. 42eXplore. Accessed December 16, 2008. http://42explore.com/respsyst.htm
Marcus, Mary Brophy. Breakthroughs in Artificial Lungs Could Assist in Transplants. Updated January 30, 2008. USA Today. Accessed December 16, 2008. http://www.usatoday.com/news/health/2008-01-29-artificial-lungs_N.htm
Respiratory System. Last updated August 8, 2007. Wikipedia Free Online Encyclopedia. Accessed August 12, 2007. http://en.wikipedia.org/wiki/Respiratory_system
Rodriguez-Cruz, Edwin. Extracorporeal Membrane Oxygenation. Last updated June 14, 2006. eMedicine, WebMD, Inc. Accessed October 13, 2008. http://www.emedicine.com/ped/TOPIC2895.HTM
ContributorsJay Shah, Malinda Schaefer Zarske, Denise W. Carlson
Copyright© 2008 by Regents of the University of Colorado.
Supporting Program (Return to Contents)Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder
Acknowledgements (Return to Contents)
The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education and National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.