This was our second assignment for this unit of the Preparing for Success Program. I no longer have the exact task information, or the mark received for this assignment, however I received an overall Distinction for this unit. For this report I needed a volunteer (my son lol) and had him perform some basic exercise after filling out a pre screening tool, then recorded results as detailed.
Please note my writings are published for educational purposes only, all of my works have been submitted to Turnitin so please do not copy and paste or you will be flagged for plagiarism. My reference list is included at the bottom.
Homeostasis is defined as the body’s mechanism for maintaining a constant and stable internal environment necessary for survival despite external changes (The Editors of Encyclopædia Britannica, 2017). Normal cell function requires the slight amount of fluid around each cell to remain within a limited range to maintain a consistent internal environment (Seeley, 2006).
During exercise, the heart, lungs and other primary body systems are challenged by the impacts of exercise, prompting a homeostatic response to bring balance back to the internal environment (Crilly, n.d.). Lung homeostasis is achieved by increasing the breathing rate to deliver more oxygen to the muscles to restore any oxygen loss during exercise and expel excess carbon dioxide, while the heart rate increases to more efficiently deliver nutrients and energy to the muscles (Crilly, n.d.). Exercising induces a rise in body temperature, resulting in the production of sweat to promote a cooling environment to aid in the removal of heat and bring the body temperature back to normal (Crilly, n.d.).
This process is known as a negative feedback loop, whereby the body produces an opposite response to an event to stabilise the internal environment (Albert, 2016). An example of this process is when body temperature increases from the normal temperature, the body will begin to produce sweat and the veins will dilate to allow for increased blood flow to the skin to be cooled by the perspiration. This then lowers the body temperature back to the normal level and thus achieves homeostasis (Albert, 2016).
The hypothesis is that the mild level of exercise performed during the experiment will cause the body to increase heart and breathing rates to generate an increase in oxygen to the muscles, and increase perspiration to help cool the body temperature.
Method and Materials
The experiment was performed with a volunteer and an observer to record results. The volunteer completed a pre-exercise screening form to determine their suitability for the experiment (see Appendix A). The volunteer was a moderately fit and healthy, though slightly overweight 18-year-old male with a history of mild, exercise-induced asthma. The exercise performed was of a mild to moderate level, repeatedly marching up and down a short steep hill. The exercise was undertaken outdoors on a mid-afternoon winter’s day in full sunlight, the recorded temperature was 19°C.
The materials used in the experiment included a stopwatch app on an iPhone to time the exercise blocks and heart/breathing rates; and a pen and paper to note the results onto a printed table. The heart rate was measured for the first reading, after the second exercise block and for the final reading through the radial pulse on the wrist; and after the second, third and fourth exercise blocks with a hand placed on the chest over the heart. The breathing rate was measured by placing a hand over the volunteer’s chest and both watching and feeling the rise and fall of the chest. The perspiration level was measured by placing a hand on the volunteer’s forehead to detect sweat/clamminess levels and by observing any visible sweat on the volunteer.
The heart rate and breathing rate were recorded for 15 seconds then multiplied by four to obtain per minute results. The first results were collected before any exertion to establish a resting rate prior to exercise. Then four individual two minute blocks of exercise for a total exercise period of eight minutes were performed with results collected after each two-minute period. A final set of results were recorded after a two-minute rest period.
Table 1. Recorded levels of heart rate, breathing rate and perspiration over the 10-minute duration of experiment.
Table 1 above shows that the heart rate increased until 6 minutes then started decreasing, with the breathing rate fluctuating slightly before decreasing after the rest period. Perspiration increased mildly during exercise.
Figure 1 below reveals that the heart rate increased steadily until the third block of exercise upon which it started to decline, falling back to the pre-exercise level after the rest period.
Figure 1. Heart rate recorded during eight minutes of exercise followed by a two-minute rest period.
Figure 2 below indicates the breathing level fluctuated back and forth by a small amount before sharply decreasing after the rest period.
Figure 2. Breathing rate recorded during eight minutes of exercise followed by a two-minute rest period.
In Figure 3 below, the perspiration levels increased steadily at a moderate pace, not easing after the rest period.
Figure 3. Perspiration level recorded during eight minutes of exercise followed by a two-minute rest period.
During exercise, muscles use an increased amount of energy. This generates several responses from the body to produce more energy to be able to continue exercising and re-establish homeostasis. First the breathing rate quickens followed by the heart rate rising, and finally the onset of perspiration is induced to cool the body temperature and restore homeostasis (Sherwood, 2015).
When exercising, the heart rate increases to facilitate the delivery of oxygen to the muscles and vital organs. Chemosensitive afferent fibres in muscles detect changes between the metabolism and blood flow in the muscle which then triggers the sympathetic nervous system to raise blood pressure to boost muscular blood flow and decrease metabolites (Rowell & O’Leary, 1990). The arteries are responsible for delivering oxygen through the blood stream, thus when the need for oxygen increases the heart must pump more blood resulting in an accelerated heartbeat (New Health Advisor, n.d.). When the exercise activity has finished, the heart rate decreases quickly during the initial few minutes after moderate exercise with the recovery period becoming longer after heavier exercise (Javorka, Zila, Balharek & Javorka, 2002). Figure 1 demonstrates an initial increase in heart rate from followed by a gradual decrease as the experiment progressed then illustrates the faster recovery period experienced after the moderate level of exercise performed in the experiment.
Additionally, heavier usage of muscles while exercising generates a higher heat output causing the body’s temperature to increase. Perspiration and elevated blood flow in the skin help the body to dispel heat, the evaporation of perspiration allowing efficient cooling (Gleeson, 1998). Figure 3 shows that the participant’s perspiration levels increased to an intermediate level during activity and did not decrease after the two-minute rest period.
As hypothesised, mild exercise increased the heart rate, breathing rate and perspiration levels exhibiting homeostatic activity in the body. Heart rate increased consistently then decreased (see Figure 1), while the breathing rate increased slightly then fluctuated mildly between two points (see Figure 2). Perspiration increased only mildly (see Figure 3).
This experiment was performed to demonstrate how homeostasis is restored and maintained during exercise. Heart rate, breathing rate and perspiration levels were measured to establish how exercise effects homeostasis. Increased muscular activity prompts an elevated heart rate to deliver more oxygen to the muscles, while breathing rate increases to bring oxygen into the blood stream via the lungs and expel carbon dioxide. Sweat increases to provide an evaporative cooling system to lower the internal body temperature. The results of this experiment show that the body effectively works to restore and maintain homeostasis during exercise with the body systems all working together to stabilise the internal environment.
Albert. (2016). Positive and Negative Feedback Loops in Biology. Retrieved from https://www.albert.io/blog/positive-negative-feedback-loops-biology/
Crilly, M. (n.d.). Homeostasis of the Body After Exercising. Retrieved from http://livehealthy.chron.com/homeostasis-body-after-exercising-7290.html
Gleeson, M. (1998). Temperature regulation during exercise. International Journal of Sports Medicine, 19(S 2), S96-S99.
Javorka, M., Zila, I., Balharek, T., & Javorka, K. (2002). Heart rate recovery after exercise: relations to heart rate variability and complexity. Brazilian Journal of Medical and Biological Research, 35(8), 991-1000.
New Health Advisor. (n.d.). Why does exercise cause heart rate to increase? Retrieved from http://www.newhealthadvisor.com/why-does-heart-rate-increase-during-exercise.html
Rowell, L. B., & O’Leary, D. S. (1990). Reflex control of the circulation during exercise: chemoreflexes and mechanoreflexes. Journal of Applied Physiology, 69(2), 407-418.
Seeley, R. R. (2006). The human organism. In R. R. Seeley., T. D. Stephans., & P. Philip (Eds.), Anatomy & physiology (7th ed., pp. 5-12). Boston, Mass: McGraw-Hill.
Sherwood, C. (2015). The effect of exercise on homeostasis. Retrieved from http://www.livestrong.com/article/480961-the-effect-of-exercise-on-homeostasis/
The Editors of Encyclopædia Britannica. (2017). Homeostasis. In Encyclopædia Britannica. Retrieved from https://www.britannica.com/science/homeostasis