TEACHER’S GUIDE
the
new
Living
body
HOMEOSTASIS
FILMS FOR THE
HUMANITIES &
SCIENCES
®
5990
Program Summary
The topic of homeostasis covers a very wide range of metabolic processes. In order to understand homeostasis in a natural setting, we observe what happens to the body during a
marathon race. We begin with the opening preparations and, by monitoring the various physiological responses of one of the runners, we show the many changes and adjustments being
made in the body as the race progresses.
The data obtained from the runner are used to explain in detail how the body regulates temperature, blood oxygen, blood glucose, water balance, heart rate, breathing rate, and hormone levels. The concept of homeostatic feedback loops is demonstrated in a real-life situation. By the
end of the race it is clear which runners have managed to perfect their homeostatic balancing
act and which have not. The program closes by summarizing the consequences of such a grueling test of endurance, and describes the strategies needed to return the body to good condition.
Background Information
Claude Bernard—Pioneer of Experimental Medicine
Claude Bernard was born in France in 1813. Although a qualified physician, he never practiced medicine but instead turned his attention to studying physiology. Using mainly dogs and
rabbits for animal experiments, Bernard made many discoveries, including:
• the chemical change of all carbohydrates into simple sugars during digestion
• the presence of enzymes in gastric juice
• the role of bile and pancreatic juice during fat digestion.
He also distinguished that the urine of carnivores was acid in nature, while that of herbivores
was alkaline, a discovery which led him to conclude that the difference was based on the very
complex process of digestion. He was the discoverer of glycogen, and undertook numerous
experiments on the action of nerve poisons such as curare.
However, Bernard’s greatest contribution to physiology came in 1857 when he noted that “La
fixité du milieu interieur est la condition de la vie libre” (the constancy of the internal environment is the condition for free life)—what we now know as homeostasis.
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Copyright © 2004 Films for the Humanities & Sciences ®
Learning Outcomes
By the end of the program, students should have acquired appropriate knowledge and understanding of:
• Homeostatic mechanisms within the body
• Regulation of temperature
• Regulation of blood sugar
• Feedback systems
• Role of hormones
• Water balance.
Before Viewing
Ask students to consider the ways in which the environment is constantly attempting to
modify their bodies, e.g., by fluctuating temperature, changes in humidity, bombardment with
ultraviolet radiation, etc.
1. Why do we not respond to these changes in the same way as non-living materials?
2. How does the body know that these external things are happening?
3. What sorts of things does the body do to keep itself from being changed by the environment? Are these things completely successful, or does the environment cause changes?
4. Why is it necessary to keep the body at a certain temperature and to protect it from
radiation?
After Viewing
Students can be encouraged to consolidate their learning from the program material by discussion or by answering the questions below:
1. Why does the athlete’s body release adrenaline before the race has even started?
2. Once the race has started, the first changes that we see are increased heart rate and blood
pressure. What is the purpose of this rapid increase in blood flow?
3. How does the body increase its oxygen supply?
4. Why do the runners look flushed only 20 minutes into the race?
5. The runners take in regular drinks of glucose and water. What do these two substances do
for the body during the race?
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6. Using the regulation of blood glucose as an example, explain what is meant by a negative
feedback system. A flow diagram may help you.
7. How would the athlete know if the muscles were not receiving enough oxygen and food?
8. Why are marathon runners wrapped in a thermal blanket at the end of the race?
9. What would happen if the temperature controls failed and body temperature became
abnormally high?
10. Is it possible for the higher centers of the brain to override the homeostatic systems of the
body? Explain your answer.
Follow-Up Suggestions
• Find out about other homeostatic control mechanisms such as concentration of mineral salts
in the body; blood pH; and regulation of body fat.
• Hypothermia often affects old people rather than the young. Find out what causes this problem in the elderly. What is being done locally to help prevent hypothermia deaths?
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