Lesson: Out of BreathContributed by: Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder
Educational Standards :
Pre-Req Knowledge (Return to Contents)
A basic understanding of red blood cells (Lesson 5) is necessary for this lesson.
Learning Objectives (Return to Contents)
After this lesson, students should be able to:
Introduction/Motivation (Return to Contents)
Did you know that you can live for about thirty days without food, three days without water, but only three minutes without air! You breathe in and out 15-25 times (approximately 250 ml of oxygen and 200 ml of carbon dioxide) per minute without even thinking about it! Every organ in our body needs oxygen in order to function properly and keep us alive. The respiratory system delivers this precious oxygen to our blood that then delivers it throughout our body, just as we learned in the circulatory system. The harder your body is working (exercising), the more oxygen it needs, which causes you to breathe harder and faster.
The respiratory system is made up of trachea, bronchi, alveoli and the lungs. These organs are protected by your rib cage, which helps us breathe by moving as we breathe in and out. When we breathe in, our rib cage swings up and out: making more space for air to enter our lungs. When we breathe out, our rib cage moves down and back: pushing air from our lungs out our nose and mouth.
Sometimes people have lungs that do not work properly. There are many lung diseases that can affect how well a person is able to breathe, such as asthma, emphysema, bronchitis and pneumonia. By studying the respiratory system and lung diseases, chemical engineers can develop medicines to treat these diseases (e.g., inhalers for asthmatics). Engineers are also working on developing an artificial lung that would allow patients to live long enough to fight off potentially deadly infections. Currently, however, the artificial lung is only suitable to use for about two weeks. The artificial lung is approximately 18 inches long and consists of membranes that pass oxygen to the blood and remove carbon dioxide. The way in which the artificial lung is inserted is very interesting: it is inserted through a vein in the leg and lodged in the main vein (the vena cavae), passing blood to the heart. The blood is re-oxygenated through a catheter that is attached to an oxygen supply.
What happens to an astronaut's lung when traveling in space? Can you guess? Can a person breathe in space with out any help? No, they cannot, because there is no air in space. The respiratory system needs oxygen and pressure to push the air in and out of the lungs. This is where engineers can help.
Inside a spacecraft, engineers have designed systems to provide the right amount of oxygen and air pressure — similar to the air and pressure provided while flying in an airplane. The body's respiratory system is probably the least affected during spaceflight as long, provided there is plenty of oxygen available and the air pressure inside the spacecraft remains at an appropriate level. This is the same for the specially engineered space suits that astronauts have worn when they walk on the moon. The main difference when breathing in space is that there is a decrease in lung capacity — meaning astronauts cannot take in as much oxygen in a single breath as they can on Earth. Due to weightlessness, the organs in the abdominal cavity are no longer pulled downward causing them to shift up and press on the diaphragm. This decreases how much air the lungs can take in during a single breath. Although astronauts cannot inhale as much air at one time, this change is quickly reversed once they return to Earth.
Today, we are going to learn more about how the respiratory system works and how engineers help people with respiratory problems and help astronauts travel in space.
Lesson Background & Concepts for Teachers (Return to Contents)
The respiratory system consists of the trachea, bronchi, alveoli, and the lungs and is responsible for gas exchange between the environment and the body (delivery of oxygen from the lungs to the bloodstream and elimination of carbon dioxide from the bloodstream to the lungs). This system — along with the heart (located between the lungs; in fact, the left lung is slightly smaller to accommodate the heart) — is located in the thoracic cavity of the ribcage that provides protection. The diaphragm muscle separates this system from the abdominal cavity. See Figure 2 for an illustration of the chest cavity.
Air first enters the body through the nose or mouth and then travels down the throat to the trachea (windpipe). Rings of cartilage protect the trachea from collapsing and subsequently blocking air from entering the lungs. The trachea then splits into two large tubes (one for each lung) called the right and left bronchi. The bronchi split into smaller bronchi and eventually become tiny bronchioles inside the lungs (see Figure 3). These bronchioles end in clusters of alveoli, which are tiny, thin-walled, air sacs that inflate as air enters the lungs and deflate as air exits (see Figure 4). The average, adult lung contains approximately 300 millions of these expandable sacs. Gas exchange then occurs between the alveoli and the pulmonary capillaries (tiny blood vessels) that lie within the alveoli walls. During inhalation, oxygen travels from the alveoli (high oxygen concentration) to the blood (lower oxygen concentration). Oxygen is then stored in the hemoglobin of the red blood cells to be delivered to the rest of the body. Conversely, during exhalation, carbon dioxide travels from the blood to the air.
During inhalation, the diaphragm contracts downward and rib muscles pull upward causing air to fill the lungs (increases the volume of the thoracic cavity and decreases pressure in the lungs so the air will flow from the higher-pressure environment to lower-pressure area in the lungs). The diaphragm then relaxes, and the lungs contract which causes air to be pushed out from the lungs (exhalation).
Some common types of lung disease are:
Vocabulary/Definitions (Return to Contents)
Associated Activities (Return to Contents)
Lesson Closure (Return to Contents)
The respiratory system is closely linked with the circulatory system (they are even sometimes combined into the cardiovascular system since the heart, blood and lungs work together to provide oxygen to the body). The ability for air to reach the lungs and the lungs to deliver oxygen to the bloodstream (and elimination of carbon dioxide from the bloodstream to the lungs) is vital to the survival of the rest of the systems of our body. Without breathing, our whole body would shut down from lack of oxygen in the bloodstream. It is a good thing we breathe without having to remember or even to think about it!
Who remembers the organs in the respiratory system? (Answer: The trachea, bronchi, alveoli and lungs.) These are protected by your rib cage, which also helps us breathe by moving in and out. Place your hand over your ribcage. Can you feel it moving in and out as your breath?
How do engineers help people who have respiratory problems? Chemical engineers have created medicines for people with asthma, emphysema, bronchitis and pneumonia. Engineers have also designed an artificial lung to help people fight off infections. Lastly, engineers help design systems to give astronauts the right amount of air pressure and oxygen to survive in space!
Assessment (Return to Contents)
Discussion Question: Solicit, integrate and summarize student responses.
Voting: Ask a true/false question and have students vote by holding thumbs up for true and thumbs down for false. Count the votes and write the totals on the board. Give the right answer.
Lesson Summary Assessment
Send-a-Problem: Have students write their own questions about the respiratory system. Each student on a team creates a flashcard with a question on one side and the answer on the other. If the team cannot agree on an answer they should consult the teacher. Pass the flashcards to the next team. Each member of the team reads a flashcard and everyone attempts to answer it. If they are right, they pass the card on to another team. If they feel they have another correct answer, they can write it answer on the back of the flashcard as an alternative answer. Once all teams have tested themselves on all the flashcards, clarify any questions.
Thoughtful Questions: Ask the students the following extension questions about the respiratory system
Lesson Extension Activities (Return to Contents)
Have the students investigate the diaphragm and how it used when we breathe. How do they think the diaphragm changes during space flight? (Answer: The muscles shrink in a microgravity environment.) Relate this back to any lessons on the muscular system (e.g., Lesson 2 of the Bioastronautics unit). How might engineers help astronauts have a healthy diaphragm in space? The following National Space Biomedical Research Institute website has a number of student investigations that describe some of the physiological changes that astronauts go through during space flight. They are mostly geared towards older or advanced students but may provide some ideas for younger learners: http://www.nsbri.org/HumanPhysSpace/
References (Return to Contents)
BBC News, Heath, "Artificial lung breakthrough," April 26, 2001. www.bbc.co.uk/news Accessed May 23, 2006
Lujan, Barbara. and White, Ronald. National Space Biomedical Research Institute, Human Physiology in Space, Houston, TX: GPO, 1995. www.nsbri.org Accessed May 23, 2006
Short, Sr., Nicholas M. National Aeronautics and Space Administration, Information Sciences Branch, Goddard Space Flight Center, The Remote Sensing Tutorial (RST).
U.S. Department of Health and Human Services, Office on Women's Health, National Women's Health Information Center (NWHIC), GirlsHealth.gov, Body – Becoming a Woman, "Learn about your whole body – from your heart to your bones," March 2006.
U.S. Department of Health and Human Services, Office on Women's Health, National Women's Health Information Center (NWHIC), Lung Disease, March 2006.
U.S. National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) Program, Bronchi, Bronchial Tree, and Lungs, "Bronchi and Bronchial Tree."
ContributorsTeresa Ellis, Denali Lander, Malinda Schaefer Zarske, Janet Yowel
Copyright© 2006 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.