The Maintenance of Human Homeostasis of Heart Rate, Breathing Rate, and Body Temperature
During Exercise
Abbey Krupp
BIO-204: Fundamentals of Human Physiology
September 29 2015
Introduction
The human body functions best when homeostasis is maintained. Homeostasis is defined
as the tendency to maintain stability in the internal environment (Kjellstrand 2012). When
changes are detected by physiological mechanisms, the regulatory mechanisms help to maintain
homeostasis. Negative feedback loops work to maintain homeostasis. Sensors are activated by a
deviation from a set point, and an effector responds to oppose the deviation (Fox 2009). The
measurements of heart rate, breathing rate, and body temperature are examples of the body using
homeostasis. During exercise the heart rate increases in order to provide the working muscles
with oxygen (Javorka 2003).
This lab observed exercise’s effect on three factors of the human body: heart rate,
breathing rate, and body temperature. The purpose of the lab was to determine how exercise
affects such physiological measurements and the role of homeostasis. It was predicted that the
heart rate and breathing rate would increase once exercise began. It was also predicted that the
body temperature would stay relatively normal as exercise continued. During exercise the heart
rate and breathing rate will increase to supply the body with enough oxygen, and the body
temperature will stay relatively normal. After exercise the body begins to adjust to its normal
state. The heart rate and breathing rate will decrease and return to normal, and the body
temperature will relatively stay the same. When the body is at rest, the heart beats at a rate of
about 70 to 80 bpm (Abrahams 2015).
Methods
There were nineteen individuals who participated in the tests. Each individual exercised
for ten minutes at two minute intervals. After two minutes of exercise, heart rate, breathing rate,
and body temperature of each individual was recorded. Body temperature was measured by a
thermometer placed under the individual’s armpit. Breathing rate was calculated by counting the
number of breaths in fifteen seconds and multiplied by four to acquire the breathing rate per
minute. The heart rate was taken by the brachial artery at the wrist. Once the exercise had
stopped, the same measurements were taken for the next twenty minutes at two minute intervals.
Results
Heart rate increased during exercise. Once exercise was completed, heart rate declined to the
resting rate taken prior to the exercise (Figure 1).
Average Heart Rate (beats/min)
160
140
120
100
80
60
40
20
0
0
2
4
6
8
10 12 14 16 18 20 22 24 26 28 30
Time (min)
Figure 1. Average heart rate during exercise (2-6); rest period (7-16).
Next it was determined that the body temperature increased once the exercise had begun. As the
individuals increased the time of exercise, the body temperature was relatively stable. At the time
of rest period the body temperature slowly decreased (Figure 2).
Average Body Temperature (°F)
96.2
96
95.8
95.6
95.4
95.2
95
94.8
94.6
94.4
94.2
0
2
4
6
8 10 12 14 16 18 20 22 24 26 28 30
Time (min)
Figure 2. Average body temperature during exercise (2-6); rest period (7-16).
Finally, the average breathing rate results showed that as the individual began exercising the
breathing rate increased and leveled off until the rest period. During the rest period the breathing
Breathing Rate (Breaths/minute)
rate decreased to the original rate and leveled off throughout the rest of the time (Figure 3).
35
30
25
20
15
10
5
0
0
2
4
6
8
10
12 14
16
18
20
22 24
26
28
30
Time (min)
Figure 3. Average breathing rate during exercise (2-6); rest period (7-16).
Discussion
We predicted that the heart rate and breathing rate would increase during exercise. We
also predicted that the body temperature would stay relatively normal. The first prediction was
supported. The second prediction was correct as the body temperature stayed relatively normal.
As the exercise continued the heart rate and breathing rate increased to supply oxygen to the
working muscles. As the body uses energy homeostasis kicks in and the physiological
mechanisms needed to supply the body with the energy it needs are put into place. The
cardiovascular system controls the heart rate. It controls the amount of oxygen pumped to the
muscles depending on the workload of the exercise (ArcMesa 2015). At the beginning of
exercise there is an accumulation of carbon dioxide in the blood. The body also has chemical
receptors in the brain which respond to changes in the blood’s pH and partial pressure of carbon
dioxide and oxygen (ArcMesa 2015). The respiratory centers in the brainstem are the control
center of the respiration system. The effectors include the pulmonary vasculature which dilates to
allow a larger quantity of blood to the lungs. This is the negative feedback loop of the respiratory
system.
Literature Cited
Abrahams, P. (2015). Conducting System of the Heart. In The Human Body (p. 122). Bright Star.
ArcMesa Educators. (2015). Exercise Physiology Basics. Retrieved September 29, 2015.
Fox, Struat Ira. “Chapter 1.” Fundamentals of Human Physiology. Dubuque, IA: McGraw-Hill,
2009. 3. Print.
Javorka, M., Žila, I., Balhárek, T., & Javorka, K. (2003). On-and off-responses of heart rate to
exercise--relations to heart rate variability. Clinical Physiology & Functional Imaging,
23(1), 1.
Kjellstrand C, Rahman, M. A., & Ing, T. S. (2012). Dialysis: History, Development, and
Promise. New Jersey: World Scientific Publishing Company.