Qualitative Data
During the course of the experiment, the test subject when dehydrated seemed sluggish with her movements. When she drank more than 1500 mL of water she made multiple trips to the washroom. The heart rate was measured using the radial pulse which was quiet distinct and moderately strong. The environment where the heart rate was taken was warm and the test subject also seemed anxious and stressed in a few occasions.
Data Processing
Overview
I have chosen to use the format of tables to show the heart rates with different amounts of water consumption. I have also chosen to use a table for the mean, Standard Deviation, and the Student’s T-Test of the 100mL and 2000mL of water. I chose to use tables because it provides a clear understanding of the collected data and because they are one of the most useful and simple way of data presentation. I have chosen to use a scatter graph with a line of best fit to compare the results because it is the best way to visually show the relationship between heart rate and the amount of water consumption.
Sample Calculations
Average
Sum of observations
Number of observations
= 79+83+80+82+78
5
= 241
5
= 241 beats/3 minute
T-Test
Formula:
T= X1-X2
√( (N1-1)S211+(N2-1)S22)/ (N1+N2-2(1/N1+1/N2 )
X1 = Mean in Sample 1
X2 = Mean in Sample 2
N1 = # in Sample 1
N2 = # in Sample 2
S21 = Variance in Sample 1
S22 = Variance in Sample 2
T= 80-69
√( 5-1)(4.30) + (5-1)(12.69))/((5+5-2)(1/5 + 1/5))
= 11
√( (67.96)/(8)(2/5)
= 11
√(67.96)/(16/5)
= 11
√( 21.34)
=11
4.61
T value= 2.39
Heart Rate
Mean number of heart beats per 3 minute
3 minutes
= 241.2
3
=80 beats/minute
Data Presentation
Table 7. Mean Heart Rate with different amounts of water consumption and its Standard Deviation
*SD calculated using Microsoft Excel
Graph 1. The effect of the heart rate after different amounts of water consumption.
*All error bars represent 1 Standard Deviation from the mean.
Table 6. Mean, Standard Deviation and Student’s T Test on the 2000mL control and the 100mL of water consumed.
Conclusion and Evaluation
Conclusion
The results of the experiment support my hypothesis that the heart rate will increase if the amount of daily water consumption decreases. As Graph 1. shows, the heart rate was the highest at 80 bmp when the test subject only consumed 100mL of water a day and the heart rate slowly and steady decreased with every increase of water consumption to 69 bmp with 2000mL of water consumed.
This increase in heart rate is due to dehydration. Dehydration causes there to be less fluid in the blood and thus a lower blood volume. In order to maintain a constant total flow of blood, the heart has to work harder and beat faster if there is less blood volume in the cardiovascular system. What would usually take one pump to circulate the blood around the body is not enough and hence, the heart has to beat more often. The overall result is an increased heart rate.
The results of experiment emphasises the importance of hydration and a daily 8 cups or 2000mL of water consumption daily. A study done by S. J. Montain and Ed Coyle confirms that the heart rate does increases when a person is dehydrated and water is lost.
Water is an important part of our daily life. It makes up approximately 60% of an adult’s body weight. Water helps move nutrients through and waste out of the body. It protects cells as they move through blood and lubricates other organs such as the eyes and mouth. Water also helps humans maintain body temperature. Water has the role of a heat conductor and regulator in blood and dilutes minerals, glucose and other materials in the body which helps maintain pH levels. Most of the water consumed is evaporated when blood vessels dilate and blood flows close to the skin. Water is also lost though sweating, urinating and bowel movements. Due to the fact that the body does not store its water, hydration is essential to stay healthy.
Limitations
There were a few limitations to the experiment such as errors of the amount of water to be consumed by the test subject. Measuring the amount of water could have had some errors due to parallax when using a measuring cup. This could increase or decrease the amount of water consumed by the test subject. There was also some spillage when the test subject was trying to drink the water. This could decrease the amount of water consumed by the test subject. It was also difficult to control what the subject ate for breakfast and lunch. Some food products did have some liquid in them and could increase the test subject’s blood volume and in turn lower the heart rate. Measuring the heart rate also posed some difficulty. There could have some counting errors counting over 200s. Another factor could be not starting and stopping to count at exactly 0 seconds and at 3 minutes. The loud environment also causes difficulty to count and feel the pulse of the test subject. Moreover, urinating during the experiment decreases the overall blood volume and could potentially lower the measured heart rate. Outside Factors such as the emotions of the test subject can also increase heart rate. When she was asked what emotions she felt during the duration of the experiment, excitement, stress, anxiety and fear were notable because those emotions tend to raise the heart rate. The test subject also on a few occasions ate something a few minutes before measuring her heart rate. Digestion can also increase the heart rate slightly because of the increase of metabolic rate during digestion. Another prevalent error is that the Test subject did not feel well during a few days of the experiment. She had a slight fever and a headache which are both factors that could cause the heart rate to rise. During a fever, the body secretes catecholamines to increase pulse rate. The result is to increase blood circulation throughout the body. This brings more blood to the vessels in the skin where the excess heat can be dissipated by the conduction and convection. These outside factors all could increase the heart rate which lowers the accuracy of the experiment that the increase of heart rate was from the dehydration. Although there were limitations in this experiment, the T-Test done for the experiment comparing the heart rate with 100mL and 2000mL of water consumed gave a T value of 2.39. Using the significant value of 0.05 for a two-tailed experiment, and 8 as the degrees of freedom, the critical number is 2.31. Since the T value for this experiment is greater than 2.31, it can be concluded that the results of this experiment are indeed significant.
Improvements
Improvements that could be made to this experiment include reducing measuring the number of pulses from 3 minutes to 2 minutes to reduce the possibility of losing count. Another improvement could be measuring the heart rate in a quiet environment where there are no distractions to better feel the pulse and to keep count. This would increase the accuracy of the heart beats measured. Using the carotid pulse instead of the radial pulse could also increase the accuracy because the pulse is stronger at the carotid artery and it is easier to distinguish and measure a stronger pulse. Using a heart rate monitor would solve many of the issues regarding measuring the heart rate. Handling the measuring cup with care should avoid spillage and bending down when measuring to avoid parallax. More trials could also increase the precision and reduce the effects of an outlier. Not allowing the test subject to eat a few hours before taking heart beats data could reduce the possibility of metabolism raising the heart rate. Delaying the experiment until the test subject was fully recovered from her fever and headache would also reduce the effect of those factors raising her heart rate. Eliminating outside emotional variables such as stress and anxiety could be difficult but perhaps a few minutes of meditation before measuring her heart rate could reduce the effect of those emotions raising her heart rate. It is difficult to control the experiment without controlling every aspect of the test subject’s life and watching her closely for the duration of the experiment.To see the further effects of dehydration on heart rate, a further addition to the experiment could include having the test subjects exercise with varying amounts of water consumption and analyzing its effects on the heart rate and how the heart rate recovers after exercise.
Works Cited
"Dehydration Symptoms, Causes, Prevention, Signs and Effects." Medicine Net. Web. 1 Mar. 2010. <http://www.medicinenet.com/dehydration/article.htm>.
"Factors That Affect Heart Rate." Pete Pfitzinger. Web. 1 Mar. 2010. <http://pfitzinger.com/labreports/heartrate.shtml>.
"How Does Temperature of the Body Influence Pulse Rate?" MadSciNet. Web. 1 Mar. 2010. <http://www.madsci.org/posts/archives/2001-06/991966089.Me.r.html>.
"Factors That Affect Heart Rate." Pete Pfitzinger. Web. 1 Mar. 2010. <http://pfitzinger.com/labreports/heartrate.shtml>.
"Dehydration Symptoms, Causes, Prevention, Signs and Effects." Medicine Net. Web. 1 Mar. 2010. <http://www.medicinenet.com/dehydration/article.htm>.
"How Does Temperature of the Body Influence Pulse Rate?" MadSciNet. Web. 1 Mar. 2010. <http://www.madsci.org/posts/archives/2001-06/991966089.Me.r.html>.
