In this activity, students learn how the human body self-regulates to maintain a stable internal environment despite changes in the external environment -- a process called homeostasis. They begin by looking at how the human body regulates temperature and the value of a fever in fighting infection. Then they use an interactive Web activity to explore other ways in which the body maintains homeostasis, such as by controlling heart rate, respiration rate, blood sugar levels, and blood pressure. Students use another Web activity to discover how infection can upset homeostasis and how the immune system fights infection. Finally, they learn how exposure to extreme environment conditions -- such as high altitude -- can affect the body's ability to maintain homeostasis.
- Understand how the human body regulates temperature and how a fever fights infection
- Explore ways in which the human body self-regulates to maintain homeostasis
- Learn how the immune system fights infection
- Explore how an extreme environment can affect the body's ability to maintain homeostasis
- Two class periods
- Fever! QuickTime Video
- Function of Fever JPEG Image
- Body Control Center Flash Interactive
- Fighting Back Shockwave Interactive
- Body Breakdowns HTML Interactive
- Alcohol swabs (for cleaning thermometers after each use)
1. Ask students:
- What is considered to be normal body temperature?
- Why do you think that normal body temperature is as high as the temperature on a hot summer day?
- How do you think an organism and its cells would be helped by a warm temperature?
2. Have students take their own temperature and report it to the class. Have the class plot these temperatures on a graph to find the mean value and the degree of variation. Ask:
- Why do you think there is so little difference in normal human body temperature while humans vary so much in other traits?
- What sets body temperature? What can change the set point for body temperature?
- How does stress affect body temperature?
- How is fever different from a simple rise in body temperature?
- What role might fever play in fighting infection?
- Why does the body sweat when a fever breaks?
4. Ask students:
- In what other ways does the body self-regulate?
5. Have students do the Body Control Center Web activity. Discuss the following:
- What is homeostasis?
- What controls human heart rate? Under what conditions does heart rate change?
- How is respiration rate controlled?
- Could you hold your breath indefinitely? What would happen?
- In what different ways does the body control temperature?
- How does the body maintain a steady level of sugar in the bloodstream? What happens if it is unable to regulate blood sugar?
- What factors control blood pressure?
- How is this Body Control Center simulation like the self-regulation that goes on in an actual human body? How is it different?
6. Ask students to explore the Fighting Back Web activity. Discuss the following:
- How does an invasion of bacteria affect the body's normal balance?
- How does the immune system fight an invasion?
7. Ask students to consider what happens when the body's ability to self-regulate breaks down. Then have students explore the Body Breakdowns Web activity to find out how climbing at high altitude affects the body's homeostasis. Discuss the following:
- Choose one part of the body from the diagram. Explain your ideas about 1) how high altitude results in a problem; 2) the symptoms that the problem would produce; and 3) how a specific action would relieve the problem.
- Consider what you know about how the human body regulates itself. What do you think might be happening in a body that results in (choose an example of symptoms from one part of the body, e.g., the stomach symptoms are intense cramps with diarrhea)?
- What do you think are the two or three most significant challenges the human body faces at very high altitude? Give reasons for choosing these.
8. Ask students to choose a body regulatory behavior and explain their own experience with this behavior, using what they have learned about homeostasis in this lesson.