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The purpose of this lab is to illustrate the ability of the kidney to alter urine output in response to ingestion of different liquids and physiological conditions.

We are testing the body’s response to the following liquids (and physiological condition) by measuring volume, color, specific gravity, and pH of urine

Coffee (inhibits sodium reabsorption – similar to effect of ADH inhibition)
Water (dilutes blood, increases blood volume)
Water + Exercise (same as water, but initially shunts water to muscles)
V8 (increases blood volume but does not dilute blood)


Determine the effects of different liquids and exercise on urine production
Learn how to perform tests to determine urine volume, color, pH and specific gravity
Describe how our treatment groups affect kidney and subsequent urine production
At the beginning of lab you will be divided into the 4 groups you signed up for last week.
Immediately before beginning the lab, each person should visit the bathroom and void any urine, which might be stored in his or her bladder.
Each person will drink 1L of his or her specific beverage (Water, V8 or Coffee). You should consume this liter within a 5-10minute time period (without causing any discomfort).
The time at which you finish your liter of beverage will be recorded as “time zero.” Starting at “time zero,” each person will void his or her bladder every 20 minutes for 2 hours (therefore there will be 6 readings).
After each 20-minute collection, you should carry out the urine measurements described below.

Special instructions:  WATER + EXERCISE GROUP

Immediately empty your bladder prior to beginning lab.
Drink 1L of water (within 5 – 10 minutes; avoiding discomfort).
Wait 20 minutes and collect your first urine sample and label cups (first urine sample).
After collection, immediately begin to conduct 20 minutes of moderate exercise. Students may climb the stairwells of CLS or walk briskly around the building.
When you return, collect your second sample.
After the second collection, you should carry out the urine measurements described below.

Volume of Urine:

To measure urine volume, void your bladder into a collection cup (volume measurements are on the side of the cup)
Record your sample volume on the data chart provided by your TA.

Note: Normal urine output for 24 hrs is 800 mL – 2000 mL (assuming ingestion of approx 2L of fluid per day).  Approximately 40 mL – 45 mL of urine per hour during the day and approximately 20 mL –25 mL per hour at night.  In addition, approximately 120 mL of filtrate is removed from the blood per minute.  This equals approximately 7.2 L (7200 mL) of filtrate per hour.  If only 40 mL – 45 mL of urine are produced per hour during the day, this means that approximately 99% of the filtrate is reabsorbed.

pH of Urine:

Measure the pH of your sample urine using the pH paper provided.
The pH is determined by matching the color of the paper to a chart on the back of the pH spool.
Record your sample pH on the data chart provided by your TA.

Note:  Normal range for pH of urine is from 4.6 – 8. Kidneys cannot produce urine of pH much less than 4.4.  Blood pH is maintained within a much more narrow range; it has an average pH of 7.4, with a range between 7.35 and 7.45. Anything outside of this range will cause acidosis or alkalosis, and can result in death if not corrected. Kidneys can use processes of tubular secretion and reabsorption to help maintain blood pH within this narrow window.

Specific Gravity:

Measure the specific gravity using a urinometer and paper towel (a demonstration will be given).
Record your sample’s specific gravity on the data chart provided by your TA.
CLEAN the urinometer with water before you hand it off to the next person

Note:  Specific gravity depends upon the amount and size of solute molecules in a given liquid.  The specific gravity of DI water is 1.000. The average specific gravity of urine is 1.003 to 1.035. Very dilute urine can be as low as 1.001.  Since the SG of water is 1.000, no value of urine can be less than 1.000.

Color of urine:

To measure the color of your urine, hold a white piece of paper behind the collection cup containing your urine sample.
Record your interpretation of the color (using the color scale below) on the data chart provided by your TA.
Once all tests have been completed and data recorded, DISCARD THE SAMPLE IN THE SINK WITH COPIUS RUNNING WATER!!!
RINSE cups used for urine collection and discard in trashcans.

Color Scale (0 – 4): 

Zero = clear;  1 = pale yellow;  2 = yellow;  3 = medium yellow;  4 = dark yellow.

Note:  The color of urine is determined by the concentration and type of solutes present.  (See textbook for details on colors and possible causes.)

Urinalysis Report Guidelines (100 points)

Page Requirement: The report should be between 7-10 pages long. Failure to meet the page requirement will result in a 10 point deduction.

Introduction (1-3 pages) essentially you have 4 different introductions; one for each beverage group*** (20 points)
Give relevant background information that you can tie to the experiment (do not just give me

the lecture) (12pts; 3 pts per intro/ beverage group)

Briefly state the objective of the experiment (4 pts)
State your hypotheses (there will be 4 for this report) 4 pts; 1 pt per intro

Hypotheses to include in the lab report:

The effect of each beverage on urine volume.
The effect of each beverage on urine color.
The effect of each beverage on urine pH.
The effect of each beverage on urine specific gravity.

URINE ANALYSIS LAB ASSIGNMENT NOTE: Your main goal for the introduction should be to explain how urine is produced in the kidneys, why analyzing urine can be beneficial, how the variables we tested are important in urine, why we did those experiments and what you thought would happen. Please be as cohesive as possible with this section. Use several paragraphs, but make sure that each flows well to the next.

Materials and Methods (10 points)
Do NOT list materials. Incorporate them into paragraph form when describing

the methods.

III. Results/Discussion (40 points)

Title each figure/table (.5 pt per figure/table) (Total Points= 2.5)
Below each figure/table discuss briefly (1-2 sentence caption) the variables being tested or

described (.5 pt per figure/table) (Total Points=2.5)

Figures to include in the lab report: (total Points 15)

Bar graph with total volume for each beverage. (3 pts)
Line graph with average change in color over 6 time points comparing each beverage. (3 pts)
Line graph with average change in pH over 6 time points comparing each beverage. (3 pts)
Line graph with average change in specific gravity over 6 time points comparing each

beverage.  (3pts)

Line graph with average change in volume over 6 time points comparing each

Beverage. (3pts)

***Write a paragraph explaining your results for each figure (do not discuss your hypothesis

here) (4 pts per paragraph; Total points=20pts)

– write a paragraph after each one

URINE ANALYSIS LAB ASSIGNMENT NOTE: Your main goal in the results section is to present your data. Discuss results here as it will make the report flow better. The reason you need a title, caption AND paragraph is because the reader should be able to get a good idea of what your graph is showing by the title and caption but you still need to write a paragraph explaining the data in more detail.

Conclusions (1-3 pages) (You will have 4 different conclusions; one for each beverage group) (24 points)
Restate your hypotheses (4 pts); 1pt per different conclusion)
Accept or reject your hypotheses and state why (6pts) (1.5 pt per)
Explain why these did or did not meet your hypothesized expectations (6 pts) (1.5pt per)
Discuss any potential errors and how they may have affected your results (4 pts) (1pt per)
Discuss (in a little bit of detail) what experiments could be done next – do not say that you

could do this over because it didn’t work or just change minor variables (4pts) (1pt per)

NOTE: Your main goal in the conclusion section is to accept/reject your hypotheses and discuss why. You also need to think critically about what may have gone wrong to affect your results. Then, you should describe experiments that could use the info from these experiments to further the research. You can be creative here!

Sources (6 points)
List at least 1 primary source that you have cited and at least 2 secondary sources that you

have cited in your introduction/discussion. (2 pts for each source)

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