The Effects Of Consuming H2O On Blood Pressure Biology Essay


Blood is carried from the heart to all parts of the body in arteries. Pulse, or heart rate, is the number of times the heart beats per minute. On average, the heart beats sixty to seventy times per minute. Blood pressure is the force of the blood pushing against the walls of the arteries (Stamler et al. 2005). Blood pressure is at its highest when the heart beats, pumping the blood, this is called systolic pressure. When the heart is at rest, or between beats, blood pressure falls. This is the diastolic pressure (Stamler et al 2005). Blood pressure is always given as systolic and diastolic pressures. Blood pressure is measured with a sphygmomanometer, which is wrapped around the upper arm, and in units of mm Hg (Weedman 2010).

Blood pressure and heart rate are affected by multiple factors, including the consumption of water. Drinking water can actually cause a very short term increase in blood pressure in some people (MacMillan). It is known that water has a great impact on blood pressure and heart rate in older people but not so much in younger people. The greater the water intake, the larger the increase in blood pressure (MacLullich). Change in blood pressure and heart rate due to water intake is only temporary. The increased volume of water in the body does not change the volume of blood or sodium in the body (Collins et al. 2006).

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Because water is not clear method of reducing blood pressure, the results of this experiment could help people determine better means of regulating their blood pressure. The effects of water on blood pressure and pulse rate were investigated by consuming sixteen ounces of water and measuring blood pressure and pulse rate at different intervals. Once water is consumed, it will increase blood pressure and pulse rate, with no effect from room temperature or cold water. Data was collected from several people to find an average change.

Materials and Methods:

Twenty six people participated in this experiment and each person drank a total of sixteen ounces of water after not consuming any liquids for a period of time. The sixteen ounces were consumed within a few minutes. At three minute intervals for twelve minutes, blood pressure and pulse rate were measured using a sphygmomanometer. These measurements were taken after consuming the water and at the three minute intervals. The data was collected from each individual and then averaged. The data from each person was collected and put on an Excel spread sheet. The average of all the data was determined in order to use a T-test and find P-values. The P-values were used to determine the significance of getting the same results again.


Table 1

Table 2

Time Intervals

Systolic BP (Series 1)

Diastolic BP (Series 2)

PR (Series 3)

0 min




3 min




6 min




9 min




12 min




*P-values are only significant if p is less than .05

Graph 1

Time (min)


0 3 6 9 12

The experiment is meant to test the effects of water on human blood pressure and pulse rate. Table 1 shows all the data collected from each subject and the average of the data. It provides three measurements for blood pressure and pulse rate before the experiment was performed. It also provides the measurement at three minute intervals after the water was consumed. Table 2 shows the P-values from the T-test. It shows the possibility of the results being obtained again if the experiment was performed again. Most of the P-values indicate that similar results could be obtained again. Graph 1 shows the P-values of systolic and diastolic blood pressure and pulse rate at different intervals of time. It shows the difference between each value at similar intervals in time.


Before the experiment was performed, it was expected that blood pressure and pulse rate would increase when water was consumed. The results of the experiment show that only part of this hypothesis was correct. Taking an average of the data, it shows that there was a slight increase in systolic and diastolic blood pressure after the water was consumed but then dropped back down as time went by. There was a decrease in pulse rate once the water was consumed and remained constant afterwards. A better hypothesis would be that when water is consumed, pulse rate will decrease and little change will happen with the systolic and diastolic blood pressure. This could possibly happen because the water is absorbed into the blood stream and requires the heart to use more pressure to move it throughout the body. Because more blood is being pushed through the body with each heart beat, the pulse rate will decrease. The results of this experiment may vary from other experiments due to systematic error, due to the way the experiment was set up, or random error, due to how the sphygmomanometer was used during each measurement. The results from this experiment may vary from other experiments performed because the effects of water on blood pressure and pulse rate differ with each individual person. The results may also vary depending on how many subjects were used to find the average. Some weaknesses in this experiment may have been using several different sphygmomanometers to measure blood pressure and pulse rate. Each sphygmomanometer may have measured differently from another and given different measurements. Another weakness would be the intervals that each measurement was taken after water consumption. Significant changes in blood pressure and pulse rate may have been more easily seen if the intervals were closer together. Also, data collected from some of the subjects was incomplete. If there were more time in the experiment, these individuals could have started over and obtained more accurate results, which would have given more accurate averages.

Literature Cited:

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Collins R, Peto R. 2006. Blood pressure, stroke, and coronary heart disease. Lancet: 1534-1535.

MacLullich AMJ, Ferguson KJ. 2001. Higher systolic blood pressure is associated with increased water diffusivity. Stroke 40: 3869-3871.

MacMillan, L. Water helps raise blood pressure in some. Reporter. 29 Jan. 2010. <>.

Stamler J, Neaton J. 2005. Blood pressure, systolic and diastolic, and cardiovascular risks. Arc Intern Med: 598-615.

Weedman D, Sokoloski ES. 2010. Lab Topic 19: Human Cardiopulmonary Physiology. A Laboratory Manual for LIFE 103: 173-184.