Anatomy and Physiology unit 5 assignment 3

by josiemcolesgmailcom (student)

Investigating homeostatic responses to exercise

Homeostatis is the term used to describe constant regulation of the body’s internal conditions, this includes regulating the body’s temperature, blood sugar level, level of Carbon dioxide level and PH. For the body to work these things have to be maintained at a constant level by physiological processes, this enables the enzymes in the body to be able to work efficiently and effectively without being denatured due to unstable conditions. Homeostatis is extremely important in the body as it enables the body to be able to function without you becoming unwell, if homeostatis wasn’t carried out it could potentially lead to death if untreated. A negative feedback loop is the main process used in order to maintain homeostatis. Negative feedback is a reaction that counteracts the original stimulus such as if the levels of blood glucose increased, the body would have to produce insulin in order to bring the blood glucose levels back down to a safe level. Here is an example of the process of a negative feedback loop using increase in carbon dioxide:

During exercise, the level of carbon dioxide in the blood may increase, this is due to the rate of cellular respiration, when we exercise we carry out more cellular respiration at a faster pace as the body requires more energy to carry out more muscle contractions that take place during exercise. This means that levels of glucose and oxygen decrease while carbon dioxide and energy increase.

Body temperature may also rise slightly due to the excess energy that turns into heat as a waste product. The way that the body reacts to these changes is through negative feedback loops, as shown above.

When there is excess carbon dioxide in the blood, the chemo-receptors pick up the change and this triggers the brain to react in different ways, one way is that the heart begins to pump more quickly to get de-oxygenated blood to the lungs so that gas exchange can take place more quickly, another reaction is in the example above, we begin to breathe more so that more waste carbon dioxide leaves the body and is replaced with oxygen. If the level of carbon dioxide exceeds a level which is safe for the body’s internal functioning, the PH level can drop causing the acid level in the blood to reach unsafe levels, this can lead to acidosis which is a poisoning of the blood, if untreated this can lead to death.

When the temperature of the body (internal) increases during exercise, this is detected by thermoreceptors found in the hypothalamus however when the temperature externally increases this is detected by the thermoreceptors found on the skin. Internally, the temperature of the blood and internal environment should never exceed 37.5 degrees Celsius and should never drop lower than 36.5 degrees Celsius, a drop to low would lead to hypothermia and going too high would lead to hyperthermia although increase in temperature can also be caused by fever. When the internal temperature increases, the thermoreceptors tell the hypothalamus to trigger responses, the hypothalamus works with the skin, sweat glands, and blood vessels. Some of the responses to heat increase include, sweating and vasodilation. Vasodilation is the dilating of blood vessels so that they are closer to the surface of the skin, this means they can radiate the heat from the blood through the skin which gives the ‘flushed’ appearance after periods of exercise. Sweating is the boy’s way of releasing heat by evaporation, sweat is made up of mainly water which we produce and consume more of when exercising anyway. If the internal body temperature doesn’t decrease, this can lead to hyperthermia (also known as heat stroke), the symptoms of this include, excessive sweating, fainting, nausea and eventually this can lead to death.

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In the reaction to the increase in blood temperature the stimulus is the increase in temperature, the receptor is the thermoreceptor, the effectors are the blood vessels and sweat glands and the responses are vasodilation and sweating.

When exercising blood glucose can decrease as it is required for cellular respiration more than usual, this change is detected by the pancreas which sends glucagon into the blood stream telling the liver to convert stored glycogen into glucose which will increase blood sugar levels. The stimulus is the decrease in glucose, the receptor is the pancreas, the coordinator is the glucagon, the ...

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If homeostasis was not carried out the body would not be able to maintain a stable internal environment, and levels such as carbon dioxide, body temperature and blood glucose wouldn’t be kept stable which would have serious effects on the body, this could eventually lead to death. It’s essential for the body to maintain a constant environment otherwise the body would not be able to carry out simple functions to keep the body healthy.

Hypothesis

We will be carrying out an experiment on homeostatic responses to exercise, here are my predictions on what the results should show based on my research:

-As a result of doing exercise, heart rate should increase due to carbon dioxide increase in the blood, the increase in heart rate should help to supply blood to the lungs more rapidly to filter out of the body. Heart rate will increase when the cardiac centre in the brain detects the increase in carbon dioxide in the blood as a result of this, the cardio-inhibitory system in the brain is turned off and the cardio-acceleratory system is turned on. As a result of the brain turning on the cardio-acceleratory system, nerve impulses are sent down the sympathetic nerve to the SA node. The sinoatrial node controls heart rate by developing electrical impulses which are conducted to the heart muscle making it contract to pump blood. When nerve impulses are sent through the sympathetic nerve, the heart begins to pump more quickly and with more force making the blood.

-Breathing rate should increase slightly as blood is pumped more quickly by the heart, this would affect breathing rate as the lungs have to carry out gas exchange at a faster rate in order to bring in more oxygen which would help to supply energy to the body and to get waste carbon dioxide out of the body so the individuals will not develop acidosis.

-Blood glucose level should decrease slightly during exercise but should go no lower than 4 mmol/Litre unless the individual is a diabetic. The levels should decrease as the body requires more energy for muscle contractions glucose is used up during the process of cellular respiration. We will not be recording results for blood glucose during or after exercise however blood glucose can spike right after exercise, especially if the exercise carried out is intense or strenuous this is due to the effect of stress hormones such as adrenaline or cortisol which tell the liver to increase blood sugar levels. This is probably unlikely to happen during our experiment as the exercise will not be intense.

-As a result of more cellular respiration taking place, the body will release more energy than needed, some of this will be released as waste energy in the form of heat, this heat has to be released from the body through the skin using vasodilation, resulting in a rise in external and sometimes internal body temperature. Body temperature may increase slightly during exercise but should not exceed 37.5 degrees Celsius unless the individual is unwell with a fever (in which case they should not be taking part) if temperature does exceed this the individual should seek medical attention as they will be at risk of developing hyperthermia (more commonly known as heat stroke). Although we won’t be recording this I predict that around half an hour after exercise body temperature should go back to normal or decrease slightly due to heat being radiated from the skin through vasodilation and through the sweat glands but it should not decrease below 36.5 degrees Celsius.

Method

1.Firstly, measure heart rate and breathing rate at rest for 15 seconds, then multiply by 4 and record the results.

2.Secondly, carry out a standard period of physical exercise.

3.Lastly, measure heart rate and breathing rate again in the same way as in step 1, ensure this is done immediately after exercise.

Results

Here is the raw data of 19 people’s breathing rates in breaths per minute and heart rate in beats per minute with calculated averages:

I have collected some random pieces of data here and put them into tables again calculating the averages:

Table 1-Breating rate in breaths per minute

Table 2-Heart rate in beats per minute

Using the same people as I used in table 1 I have calculated the mean of the results for heart rate

Table 3-Temperature in degrees Celsius

(we did not record this data so the data in the table is from a previous experiment done using the same method)

Conclusion

The first results conclude that heart rate increases by an average of 10 bpm due to the effects of exercise caused by an increased need for energy through cellular respiration and so the body can pump blood to the lungs more quickly, the result of this is a higher breathing rate which is shown in the first results to increase by an average of 4 breaths per minute as the average before exercise was 16 and the average afterwards was 20 breaths per minute. These results fully support the hypothesis.

Although we were not able to record blood glucose, carbon dioxide or temperature due to regulations and lack of resources, I have a table of results for Temperature before and after exercise, the results show that the temperature of the body does not increase drastically which was as I predicted, the average temperature increase was approximately 0.24 Degrees Celsius. The temperature did however exceed 37.5 degrees in an anomalous result of 37.8 degrees, this person may have a medical condition and their temperature appeared to decrease following exercise, this was the only result which didn’t support my hypothesis as all of the other results stayed the same or slightly increased.

Evaluation

Following our experiment, I identified some flaws in the method of data collection that we used. Factors that affected heart rate and breathing rate were not kept constant as they were not considered when collecting our data so we assumed everybody to be in the same boat. On example of this would be if the individual had carried out some exercise beforehand such as walking or running up the stairs to the classroom if they were late, this would increase their heart rate, this could potentially mean that the resting heart rate for that individual is higher that the heart rate after the experiment was carried out, this is shown in anomalous results such as individual number 10 (referring to the table of results)who showed the largest decrease in heart rate, this person’s resting heart rate was recorded at 116 bpm and dropped to 104 bpm it is highly likely that this individual may have exercised beforehand, it should also be taken into account that they may be a smoker. Smoking increases heart rate as the nicotine stimulates the body to produce adrenaline which will make breathing rate and heart rate increase. However, in this individuals results the breathing rate had stayed the same, this may also be due to the way we collected the data. When measuring breathing rate, we timed 15 seconds and measured an inhalation and exhalation as 1 breath, we then multiplied the results by 4 to get rate of respiration in breaths per minute, this is an easier way to calculate rate of respiration but it is very unspecific and errors are more easily made, if a small error was made in those 15 seconds, the error would have been multiplied which would make the results even less accurate. If we had timed for a minute and measured breathing rate, the results would have been less open to errors as small errors would not be multiplied. We used the same method for heart rate which could have had a large impact on the overall results.

Another factor that could affect the heart rate or breathing rate of an individual is either medication or a medical condition. One individual appears to have an extremely elevated heart rate, they were number 7 on the table of data, their heart rate was 108 resting and 148 after exercise, this could be down to a number of things, the individual may have the condition tachycardia which causes elevated heart rate and palpitations, they may smoke or have drunk coffee prior to the exercise, may have anxiety or they may be on medication such as birth control, all of these have an effect on heart rate. The heart rate recorded was far from average for the individual’s age group and the physical exercise endured as the highest heart rate should be around 200 when enduring intense physical exercise.

Furthermore, during our experiment we did not set a pace or time in which the individuals had to complete the period of exercise, it was at each individual’s discretion, this made the results much more varied leading to inaccuracy, one may have run up and down the stairs while another may have taken small steps at a slow pace, these two individuals would return to the classroom with different levels of exercise and therefore different rates of homeostatic response. A way to improve this would be to set a pace that each individual should stick to such as taking 2 steps per second, you would still achieve some variation but the results would be much more accurate.

Another point I should make is that some people may have walked more slowly back to the classroom meaning their heart rate and breathing rate would have had some time to begin to recover, meaning it shouldn’t be recorded as being straight after exercise. We also had to measure our heart rate before our breathing rate or vice versa as everybody returned at different times, this meant that some people’s heart rate would be more recovered than their breathing rate, whilst other people’s breathing rate would be more recovered than their heart rate, a way to prevent this from happening in another experiment would be to use appropriate equipment such as using a vital signs monitor which is usually found in hospitals, this piece of equipment usually measures heart rate, oxygen saturation, temperature, rate of respiration and blood pressure at the same moment in time making this much more accurate.