Chapter 23 The Circulatory, Respiratory, Digestive, and Excretory ...

Figure 23.17: Cigarette warning labels unveiled on 6/21/2011 by the U.S. Food and Drug Administration.
Lesson Summary
• Respiration is the process in which gases are exchanged between the body and the outside air. The
lungs and other organs of the respiratory system bring oxygen into the body and release carbon
dioxide into the atmosphere.
• Respiration begins with ventilation, the process of moving air into and out of the lungs. Gas exchange
in the lungs takes place in across the thin walls of pulmonary arteries in tiny air sacs called alveoli.
Oxygenated blood is transported by the circulatory system from lungs to tissues throughout the
body. Gas exchange between blood and body cells occurs across the walls of peripheral capillaries.
• Gas exchange helps maintain homeostasis by supplying cells with oxygen, carrying away carbon
dioxide waste, and maintaining proper pH of the blood.
• Breathing occurs due to repeated contractions of a large muscle called the diaphragm. The rate of
breathing is regulated by the brain stem. It monitors the level of carbon dioxide in the blood and
triggers faster or slower breathing as needed to keep the level within a narrow range.
• Diseases of the respiratory system include asthma, pneumonia, and emphysema.
Lesson Review Questions
Recall
1. What is respiration? What is ventilation?
2. How is respiration different from cellular respiration?
3. Outline the pathway of a breath of air from the nose to the alveoli.
4. Describe how pulmonary gas exchange occurs.
5. Identify three diseases of the respiratory system, and state what triggers or causes each disease.
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