Kidneys
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Kidneys EN_1
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1 of 14: Introduction
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Introduction:
In this experiment you will investigate now the kidneys handle fluid loads. These include water alone, and isosmotic salt and monosaccharide solutions, as well as a hyperosmotic monosaccharide solution.
Learning Objectives By the end of today's laboratory you will be able to
■  Describe how the kidneys handle a water load
• Distinguish between the handling of water and isosmctic salt loads
• Explain the pattern of fluid excretion following isosmotic and hyperosmotic monosacchar de loads
• Discuss the relationship between urine osmolarity and specific gravity and how osmolarity is affected by changes in urine flow rates
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LabTutor
Kidneys EN_1
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2 of 14: Setup
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Refractometer RUR2-ATC
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1 Optical prism
2 Translucent cup
3 Calibration screw
4 Rubber handle
5 Eyepiece with focus
Equipment:
Refractometer. urine collection container urine transfer pipette to refractometer. test strips measuring container ana paper napkins.
Urine collection container
Test strips
Pipete
Urine measuring container
1. Applying a drop of urine to the prism of the refractometer.
2. Covering the prism with a transparent cup.
3. Reading the measured value from the scale.
4. Cleaning the prism (be careful not to scratch the prism).
Procedure:
This laboratory involves the collection of urine at various time intervals and measurement of its volume and specific gravity (an indication of osmoiarity). There are four different protocols, eacn requiring a different volunteer
Volunteer preparation
The establishment of the diuresis depends upon fairly rapid absorption of the water so it is important not to start with a full stomach Just eat a I ght meal and drink normally in the 3 to 4 hours Defore the laboratory starts, in addition, avoid fluids containing caffeine feoffee, tea cola drinks) for at least 3 hours prior to tne laboratory.
O Be sure to note the time at which you last urinated prior to coming to the laboratory
Refractometer measurement
1. Preparation for measurement (handle the device with care and do not touch optical lens).
Set direction of the refractometer transparent cup against the light look into the eyepiece and sharpen the image to improve readability. You will see a circular space with a measuring scale .
2. Refractometer calibration.
Open the transparent cup; put 1 to 2 drops of the calibration solution (distilled water} on the optical prism, close the cjp and press it slig fitly for the solution to spread perfectly over the surface of the optical prism (without air hubbies and dry spots). Look into the eyepiece, the top of the visor should be blue, the bottom white, and the boundary should go through a calibration value of 1.3300 (left scale of the Rl) If not, turn the calibration screw until the desired condition is reached.
3. Measurement.
Open the transparent cup, clean the optical prism with the included cloth, then put 1 to 2 drops of the test liquid (urine) on it, close the cup and slightly press it so that the liquid can spread perfectly over the surface of the optical prism (without air bubbles and dry spots) The measured value will be represented by the intersection of the blue-white boundary on the right measuring scale (specific gravity).
4. Cleaning after measurement
Clean the prism and the transparent cup with a damp cloth and carefully place the device in to the case. To wet the cloth, use Desident CaviCide spray.
General procedures during the experiments for all volunteers
1. At the commencement of the experiment, note the time, collect your urine and measure its volume. Keep a small sample for measurement of specific gravity.
2. Immediately after the collection of the first sample, drink the required solution (except control). Once you have drunk this solution, do rot drink anything else during the laboratory.
3. Continue to collect urine approximately every 20 minutes, noting the time at which the bladder is emptied to the nearest minute.
4. It will be found most convenient for each subject to be his or her own timekeeper; there is no necessity for the subjects to keep in step with each other. The essential thing is that the intervals between urination are accurately recorded.
Cautions
Ji Do not volunteer to be a subject in this laboratory class if you are suffering from kidney or circulatory problems, have any other medical problem or are on any medications.
-Ii Urine is a potentially infectious body fluid. Therefore, students are directly responsible for all measurements of the volume and specific gravity of their own urine, and are required to clean up any spilt urine themselves.
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4 of 14: Protocols
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Experimental protocols:
There are four different protocols.
Protocol 1: Control - no fluid intake during experiment.
1. Drink nothing during this laboratory and collect specimens of urine each 20 minutes or so.
2. Measure the volume and specific gravity of your urine and then dispose of the sample down the toilet.
3. Enter the volume and specific gravity of the sample into your own table.
Protocol 2: To illustrate a normal water diuresis.
1. Drink BOO mL of Solution 2, then collect specimens of urine each 20 minutes or so.
2. Measure the volume and specific gravity of your urine and then dispose of the sample down the toilet.
3. Enter the volume and specific gravity of the sample into your own table.
Protocol 3: To illustrate effects of drinking the equivalent of an isosmotic sodium chloride solution.
1. Drink E00 mL of Solution 3, then collect specimens of urine each 20 minutes or so.
2. Measure the volume and specific gravity of your urine and then dispose of the sample down the toilet.
3. Enter the volume and specific gravity of the sample into your own table.
Protocol 4: To illustrate effects of drinking a hyperosmotic glucose solution.
1. Drink BOO mL of Solution 4, then collect specimens of urine each 20 minutes or so.
2. Measure the volume and specific gravity of your urine and then dispose of the sample down the toilet.
3. Enter the volume and specific gravity of the sample into your own table.