Water Diuresis – Physiology
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Department of Physiology
Body Systems Physiology
Water Diuresis
Worksheet
What does the word diuresis refer to?
Diuresis is the increase in the rate of production of urine by the kidneys, and usually results in an increase
in release of urine from the body
What are the particular characteristics of a water diuresis?
Water diuresis is a result of an ingestion of water that is greater than required by the body. It results from
the suppression of ADH secretion, so the collecting ducts become less permeable to water and the
excess water is lost with a little or no change in the solute concentration.
In the table below record the details for each of the subjects in your group. If there were only 3 subjects in your group draw a line through the last row (Subject D).
Subject
Treatment
Body Weight
Volume of Water Ingested (litres)
Control
0.984
Exercise
0.912
Complete the data tables on the next two pages. There should be one table completed for each subject in your group. One subject will have data for urine osmolality but not ion concentrations. The other subjects will have data for urine ion concentrations but not osmolality. If there were only 3 subjects in your group write no subject available across the last data table.
For the subjects in your group plot graphs showing the effects of the various treatments on:
Rate of urine production (ml/min) versus time. Plot the data for all subjects on the one graph. Make sure you identify each subject
Urine osmolality versus time. There will be only one subject for this graph.
Urine sodium concentration versus time. There will be 2 (or 3) subjects for this.
Sodium excretion rate versus time. This will be for the same 2 (or 3) subjects as above.
Attach these four graphs to this Worksheet.
Subject: X
Treatment: No treatment
Sample 1
Drink
Sample 2
Sample 3
Sample 4
Sample 5
Sample 6
Time of day
Time interval
(min)
Urine volume
Urine flow
(ml/min)
11.70
13.00
Urine osmolality (mOsm/kg H2O)
Osmolar excretion rate (Osm/min)
282.6
297.0
340.0
Subject: X
Treatment: No treatment
Sample 1
Drink
Sample 2
Sample 3
Sample 4
Sample 5
Sample 6
Time of day
Time interval (min)
Urine volume (ml)
Urine flow (ml/min)
11.70
13.00
Na+ concn (mmol/litre)
0.524
0.351
0.076
0.044
0.069
Na+ excretion rate (mol/min)
864.60
175.50
129.20
514.80
390.00
448.50
Cl- concn (mmol/litre)
0.0524
0.0426
0.0131
0.0082
0.0066
0.0049
Cl- excretion rate (mol/min)
86.46
21.30
22.27
95.94
85.28
31.98
Subject: Y
Treatment: Moderately severe exercise (5 minutes on the bicycle ergometer with the needle at the orange/red boundary)
Sample 1
Drink
Sample 2
Sample 3
Sample 4
Sample 5
Sample 6
Time of day
Time interval (min)
Urine volume (ml)
Urine flow (ml/min)
Na+ concn (mmol/litre)
1.205
1.095
0.317
0.106
0.328
0.591
Na+ excretion rate (mol/min)
2410.00
1149.75
1458.20
858.60
902.00
709.20
Cl- concn (mmol/litre)
0.1032
0.1098
0.0246
0.0098
0.0034
0.0606
Cl- excretion rate (mol/min)
206.40
115.29
114.54
79.542
72.72
6) What is meant by the term osmolality?
Osmolality is a measurement of urine concentration that depends on the number of particles dissolved
in it and is represented by the number of solute particles per 1 kilogram of solvent.
The average data from all subjects in the entire class (all three days) will be posted on the PHY2021 WebCT site. Use this class data to answer the following:
(a) Describe what happens to the rate of urine production in the 3 different treatment groups.
The rate of urine production in the control student was increased as a result of water ingestion. However
there is a delay in the onset of this increase within the time period 20- 40 minutes (graph 1) in urine
production initially. After the 60th