Homeostasis Lab

Physiology, Berry
HOMEOSTASIS LAB ACTIVITY

Introduction: Homeostasis means maintaining a relatively constant state of the body’s internal environment. The term used to describe a pattern of response to restore the body to normal stable level is termed negative feedback. When a stimulus (environment change) is met by a response that reverses (negates) the trend of the stimulus, it is negative feedback. As a result the internal environment is returned to normal. Pulse rate is constantly checked by receptors throughout your body. A stimulus such as elevated pulse rate leads to a reaction by an organ making the response. An appropriate response will return the pulse rate to normal.

Purpose: To observe an example of homeostasis working to control your body’s pulse rate.

Materials: stop watch

Procedure:
1. Have your partner sit down and measure your partner’s pulse rate in their radial artery (wrist). Take three separate measurements, each for thirty seconds. Calculate the beats per minute by multiplying the values obtained by 2. Find an average for the three values. Record this in Data Table 1 and in Data Table 2 under Trial 1.

2. You and your partner will exercise vigorously for three minutes. Start your stop watch when you start exercising. Measure the pulse rate immediately on finishing the three minutes of activity. Record the value as Trial 2 in Data Table 2.

3. Let your stop watch continue as you rest for 5 minutes. Measure your pulse rate again. Record your pulse rate after this 5 minute rest period as Trial 3.

4. Repeat steps 2-3 two more times. Record the pulse rate after vigorous exercise as Trial 4. Record the second resting pulse rate after 5 minutes as Trial 5. Exercise again vigorously and record as Trial 6. Trial 7 will be the last measurement after 5 minutes of rest.

5. Graph the results of these trials in your lab report. Plot the resulting measurements from Trials 1-7.

6. Connect the trail values from 1, 3, 5, and 7 by a line. Connect the trail values 2, 4 and6 with a different color line. Study the pattern/patterns.

Data Table:1
PULSE RATE 1
PULSE RATE 2
PULSE RATE 3
AVERAGE

Data Table:2
TRIAL
ACTIVITY
PULSE RATE
1
Average resting pulse rate

2
3 minutes vigorous activity

3
After 5 minutes of rest

4
3 more minutes of vigorous activity

5
After 5 more minutes of rest

6
3 more minutes of vigorous activity

7
After 5 more minutes of rest

Questions:
1. What is your average resting pulse rate? Most adults are between 60-90 beats/min. How do your values compare? Explain why you believe your rate is high or low in comparison to the norm.

2. What happens to your pulse rate with vigorous exercise? How does your heart respond and why does this occur?

3. Did your body respond using homeostasis each time to cope with the disturbed pulse rate? To see the pattern of response, look at the graph of your pulse rate from trials 1, 3, 5 and 7 and compare them with your pulse rates from Trials 2,4 and 6. A fairly quick return of the pulse rate back to normal is indicative of good health. Explain your health as it relates to your data.

4. How can recording your changing pulse rate demonstrate negative feedback?

5. How do you think the results from this lab would compare for a trained athlete and an average person? Explain.

6. What are some ways your body regulates the increase of body temperature that also occurs when exercising?

Conclusion: Restate the purpose of this experiment, your findings and how your data supports your conclusion. Was your hypothesis confirmed by the experiment? Discuss. What connections do you see between body systems during this? Explain.