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Renal Function
Science Fair Project

1st Prize Winner 2006 Virtural Summer Science Fair
Renal Function Science Fair What Fluids Affect the Kidney?
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Renal Function Science Fair Project

The Effects of Different Liquids on Renal Function?

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BR>CATEGORY: Life Science
STUDENT: Jessica
GRADE LEVEL: 9th (High School)
STATE / Country: California, USA
AWARDS:1st Prize Winner of the 2006 Virtural Summer Science Fair Contest - Super Science Fair Projects

Problem Being Investigated: Which types of fluids affect the kidneys in different ways? What is the pH of the urine excreted? I will research this problem and conduct tests to answer these questions.

Abstract - Renal Function Science Fair Project

Three types of liquid were ingested (isotonic saline, tap water, and coffee) over five twenty minute intervals to determine how much urine each beverage would produce, and the pH of each of the urine from these fluids. Of the three liquids, coffee indeed did produce the most urine.

I. Purpose

The purpose of my Renal Function Science Fair Project experiment is to show the kidney’s aptitude to modify the production of urine in response to the ingestion of different liquids, such as tap water, isotonic saline (which is Gatorade or any other sports drink), and coffee. Various fluids affect the kidneys in different ways. This experiment is useful in everyday life because as I ponder on the busy, routines much of us complete daily, it would be helpful to know which fluids cause us to have to use the restroom more frequently than others. Also, it will be useful to know if certain fluids can be hazardous to our health by causing dehydration.

II. Procedure

The controls of the Renal Function Science Fair Project experiment are as follows: The participant must not consume large amounts of liquid at any meal preceding the experiment. This is to empty the bladder in order not to alter the results. The participant should also not consume drinks (other than the coffee) that contain theophylline (tea). The participant must control the amount of perspiration and condensation from the body (Also not to alter the results of experimentation). The independent variables of this experiment are the three different types of liquid being consumed. The dependent variables are how much urine that is collected at each interval.
  1. Purchase and collect the necessary materials:
    • (a) 1 Liter of Gatorade or any other generic sports drink that contains isotonic saline.
      (b) 1 Liter of Tap Water
      (c) 1 liter of regular coffee
      (d) 1 500 Milliliter beaker
      (e) Strips of pH paper
      (f) Drinking cups
      (g) Timer
      (h) Journal to record results from each experimentation

  2. Ingest one liter of tap water rapidly to minimize the total time required for ingestion.

  3. Record the time at completion of ingestion

  4. Collect urine samples at 20 minute intervals for a total of five twenty minute periods. Each collection and total volume of each should represent a complete emptying of the bladder.

  5. Record the total volume collected and the color of the urine.

  6. Test the urine by carefully holding and placing the pH paper in the beaker.

  7. Record the urine’s pH.

  8. After every measurement and color is recorded, discard the urine.

These procedures are to be repeated with each different liquid ingested.

III. Conclusion

Through experimentation, I have discovered that the tap water, isotonic saline, and coffee consumed indeed affected the kidneys in different ways. In the beginning of the experiment with the tap water, the color of the urine had a much darker coloration. As the experiment progressed, the urine became more dilute and less concentrated. The pH of the urine held steady, but fluctuated slightly from 6 to 8.The elimination of substantial amounts of urine is due to two principal factors. When the tap water was ingested, there was an increase in blood volume, which increases blood pressure and the kidney’s rate of filtration. This caused a greater output of urine. The increase in blood volume is due mainly to the increase in water. This lowers the osmotic pressure of blood which in turn inhibits the levels of secretion of antidiuretic hormones. A reduction in the level of this hormone reduces water re-absorption thus increasing the output of urine. I was able to collect an average volume of 143.06 ML of urine with the ingestion of the tap water.

With the isotonic saline I saw a result that was similar to that of the tap water. The color of the urine also started out dark in this experiment, but began to lighten towards the end. The pH of the urine did not fluctuate highly, but remained between 6 and 7. The effect the isotonic saline had on the kidneys was much like that of the tap water. The saline in the drink causes the kidneys rate of filtration to increase, as well as the blood volume. The osmotic pressure of the blood changes very little because of the effects of the saline. Through experimentation, I was able to collect an average excretion volume of 152.53 ML urine.

Towards the beginning of experimentation with the coffee I noticed the same dark coloration of urine as observed in the two other liquids. With time, the urine changed to a pale yellow-green. Some of the dark coloration could have been attributed to the concentration of the urine, but it also may have been because of the pigments in the coffee as certain colors in fluid or food have the ability to alter the urine’s color. The caffeine in coffee dilates the afferent arteriole to the kidney and greatly enhances the rate of filtration. The net result is an increase in the rate of urine formation. The pH varied slightly from a 5.5 to a 6. The coffee produced a large volume of urine. I have discovered that it produced an average excretion of 293 ML.

Here is what I would do different

: This year I have learned much about science fair projects and what is required to complete one, but I have learned a few things that I would like to use in the future. First, next year I would like to include more controls and variables in my project. For example, on the project that I did this year, I realized that another possible control could be the amount of water that is released from my body in perspiration, or exhaled breath. This control could possibly have affected the amount of urine that I collected to a minor extent, but it would still be important if I was to continue my project in the future.

In order to prove a scientific experiment, continued testing must be priority. If I was to do this project again or to continue it, I would like to spend more time testing my project (9 months to a year rather than six months) and using other liquids as well as the ones included in my experiment. Thanks Again! Jessica

Renal Function Science Fair Project Bibliography

Ahlstrom, Timothy P. The Kidney Patient's Book. Delran, New Jersey: Great Issues Press, 1991.

Inlander, Charles B. The Consumer's Medical Desk Reference. New York: Stone Song Pres, Inc.,1995. pp 289, 327, 441, 28-30.

Silverstein, Dr. Alvin. The Excretory System. New York: Twenty First Century Books, 1994

The Human Body: The Kidneys: Balancing the Fluids. New York:Torstar Books, Inc., 1985.

Wimer, L.T. Animal Physiology Lab Studies

Zhang, Z. Kindu, C. Yuan.,J Ward, E. Lee. De Mayo, H. Westphal, A. Mukherjee., "Severe Fiberonectin Deposit Renal Glomecular Disease in Mice Lacking Uterglobin.", Science 30 May, 1997:1408-1412

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