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.
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?
3.
Show students the
Fever! video
and have them examine the
Function of Fever still image.
Then discuss the following:
- 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.
