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Your blood pressure is the measure of blood pushing against your arteries. This movement of blood happens because of the heart. Your pulse is a measure of your heartbeat(American Heart Association 2009). As you can see blood pressure and pulse rates are directly related and water plays a major role in your wellbeing as well. The human body is composed mainly of water. If you fail to supply your body with ample amounts of water every day, you will suffer from dehydration. This dehydration will cause all of the systems of the body to cease functioning to their potential because the body is dependent on water. (American Heart Association 2009) When you are dehydrated cells in the body lose water. These cells need water to function so they will take water out of the blood that is circulating throughout the body. This in turn will cause your blood volume to decrease and your blood pressure to increase because the heart has to work harder (Markowitz 2009) .
One study tested whether ethnic differences had an effect on urine concentration and if there could possibly be a relationship to blood pressure and pulse pressure. This study did not confirm that urine concentration is related to blood pressure but they did find that higher urine concentration with lower volume was associated with higher pulse pressure. As far as the ethnic portion of their experiment, they found that black individuals have a higher urine concentration. This may contribute to the fact that black individuals are more susceptible to hypertension, or high blood pressure (Bankir et al. 2007).
By running this experiment we hoped to discover whether the consumption of water was related to blood pressure and pulse rate in the body. We will be able to determine the subject's blood pressure and pulse rate at various intervals with a device known as a sphygmomanometer. The sphygmomanometer is capable of recording a systolic pressure, contractions of the heart, and diastolic pressure, relaxation of the heart, as well as a pulse rate. The sphygmomanometer has the capability to record the arterial blood pressure because the cuff contains a device allowing us to do so.(Weedman and Sokoloski 2009) I hypothesized that hydration would affect blood pressure and pulse and predicted that blood pressure would increase with hydration because there will be more volume in the body, consequently raising blood pressure. I also hypothesized that pulse rate would not be greatly affected by hydration. However, there may be a slight decrease because the body might respond to the new level of hydration and not have to work as hard to achieve homeostasis since water is essential and plays a vital role in every body system.
The results of this experiment are important to know because if hydration does affect blood pressure then it could possibly help those who suffer from hypertension or individuals with slightly high blood pressure known as pre-hypertension. High blood pressure was the primary contributing cause of death for 319,000 Americans in 2005(Insel and Roth 2009) and many people, nearly 21.3%, have high blood pressure and don't even know it. (American Heart Association 2009). People could possibly help control their blood pressure simply by being more conscious about how hydrated they are. . Because high blood pressure can be hard to detect, learning more about what is linked to high blood pressure and pulse pressure for preventative reasons is vital.
Methods and Materials:
Since we were testing the effects of hydration on blood pressure, pulse, and recovery time, it was essential that the subjects being tested came into the lab slightly dehydrated. They were informed not to drink that morning so that they would be slightly on the dehydrated side. We took 3 initial blood pressure and pulse recordings, or basal readings. These recordings were crucial in order to have data to compare to our later results. We then had the subject drink 16oz of water in order to hydrate his or herself. We then used the sphygmomanometer at three-minute intervals to test the absorption of water into the body and see if this hydration affected the subject's blood pressure or pulse. In this experiment there were 26 replications with recordings taken at 0 min, 3 min, 6 min, 9 min, and 12 min. With the replications were then able to organize the data into a spreadsheet in Excel. We then calculated the means and did several TTests to identify whether our results were significant or not.
This experiment included independent, dependent, and standard variables. The independent variables were the variables that were being manipulated which included the temperature of the water and the hydration of the subject. The dependent variables were the variables being measured which included the pulse rates and blood pressures at fixed intervals. The standard variables were fixed during the experiment and included the amount of water that the subject drank (16 ounces) and the three-minute measuring intervals.
The purpose of this experiment was to determine whether or not the consumption of water has an effect on blood pressure, pulse rate, and recovery time.
Table 1 shows the averages that were used to calculate the three graphs as well as what was used to determine the 6 different TTests.
The TTest is a statistical test done in Microsoft Excel which helps calculate whether changes in data are significant or not. The results obtained were both significant and insignificant according to the TTest's preformed. Three out of six of these TTest's run had TTest numbers greater than .05 and because of this they are considered insignificant, or likely due to chance. Three of the TTests that were run were for basal systolic, basal diastolic, and basal pulse rate, vs. 0 min post systolic, 0 min post diastolic, and 0 min post pulse rate. The other three TTests that were run included basal systolic, basal diastolic, and basal pulse rate vs. 12 min post systolic, 12 min post diastolic, and 12 min post pulse rate.
Three graphs comparing average heart rates vs. time, average systolic pressures vs. time, and finally the average diastolic pressures vs. time are pictured below labeled as "Figure 1", "Figure 2" and "Figure 3". They represent an overall average of the data gathered in a visual fashion.
Table 1: Averages
Average Pulse Rate(BPM= beats per minute)
Average Systolic Reading(mmHg)
Average Diastolic Reading (mmHg)
0 min post PR
3 min post PR
6 min post PR
9 min post PR
12 min post PR
Table 2: TTEST Results
Type of Test
Basal Systolic vs. 0 min post systolic
Basal Diastolic vs. 0 min post diastolic
Basal Pulse Rate vs. 0 min post pulse rate
Basal Systolic vs. 12 min post systolic
Basal Diastolic vs. 12 min post diastolic
Basal Pulse Rate Vs. 12 min post pulse rate
I hypothesized that hydration would affect blood pressure and pulse and predicted that blood pressure would increase with hydration because there will be more volume in the body, consequently raising blood pressure. I also hypothesized that pulse rate would not be greatly affected by hydration however there may be a slight decrease. My hypothesis did not prove to be completely consistent with the data that was collected on blood pressure. However, there were some similar patterns which agree with my hypothesis leading me to believe my hypothesis was mostly correct and the experiment may have had some flaws. The data collected for pulse rates fully supported my hypothesis. In regards to the averages of the systolic and diastolic blood pressures, the graphs have similar shapes to them showing that osmosis of the extra water in the body was affecting both the systolic and diastolic pressures similarly.
I predicted that the average blood pressure would increase with hydration and the initial 0 min post averages for both the systolic and diastolic are consistent with my predictions. The 0 min post average for the systolic reading was 120.3mmHg compared to the basal reading of 111mmHg. The zero min post average for the diastolic reading was 78.6mmHg compared to the basal reading of 70.5mmHg. The data then takes a drastic decline in both the systolic and diastolic three min post and six min post readings. The systolic readings drop to 114.4mmHg and then to 110.7mmHg while the diastolic readings drop from 72.5mmHg to 71.2mmHg. This could be because the water was absorbed into the body right away and then took a little time to disperse throughout the body. If this is the case the readings at nine minutes would make sense because we see an increase once again. This increase is present in both the systolic and diastolic readings once again showing that the systolic and diastolic rates coincide. This similar increase that we see could be due to the body's osmoregulation. The systolic reading increases to 117.2mmHg while the diastolic reading increases to 76.5mmHg.
It was important to run and understand the TTests in this experiment. The TTests were statistical tests that helped us better understand whether our results were due to chance or not. Three out of the six TTests that were run had values less than .05 and were therefore significant however the other three were greater than .05 meaning these values were insignificant. The high ratio of insignificant values to significant values leads me to believe the experiment we ran is certainly onto something and possibly with further experimentation dealing with hydration, pulse rate, and blood pressure, we could discover that these changes are not at all due to chance and are happening for reasons.
The data we gathered is pretty consistent with the predictions made about pulse rate. Also, the results gathered correspond well with other studies done which state as urine concentration increases the pulse rate too increases. In our experiment the urine concentration should have decreased because of hydration therefore causing the pulse rate to decrease. We can see by looking at the graph that this did occur. The average basal reading for pulse rate was 78BPM and then drastically decreased after hydration to 71.4BPM where it fluctuated very little in all the following times intervals.
There were several weaknesses that we can identify in this experiment. For starters different people may absorb fluids into the body at different rates. Also the subjects had to estimate how much 16 ounces of water was since we did not have measuring cups. Another weakness was the initial hydration/ dehydration state of our subjects. The subjects were simply told not to drink water that morning but this does not necessarily make them slightly dehydrated. Because of this, the experiment was initially flawed before we even started. As far as our weakness dealing with pulse pressure we had to rush the experiment at the end of class and because of this it is possible that adrenalin could have factored into the high basal pulse rate readings.
I learned from this experiment that dehydration and hydration in the body definitely has an effect on blood pressure and pulse rate in the body. I also better understand how to use a TTest to interpret data which is important in scientific papers. Finally I learned how to think critically in situations where the data does not completely answer your questions.
Weedman D, Sokoloski ES. 2009. Biology of Organisms A laboratory Manuel for LIFE 103. 5th ed. Cedgage Learning. p.173-176
Bankir L, Perucca J, Weinberger MH. 2007. Ethnic differences in urine concentration: possible relationship to blood pressure. Clin J Am Soc Nephrol. Mar;2(2): 196-7.
American Heart Association. Heart disease and stroke statistics-2006 update. Circulation. 2009. 31 January 2010. www.cdc.gov/bloodpressure/facts.htm
Markowitz A. 11 December 2009. Shop Without Dropping. Chicago Tribune.
Insel P and Roth W. The Core Concepts In Health. 11th Ed. McGraw-Hill 2009. Pg. 380-383.