Water Diuresis - Physiology

Department of Physiology

Body Systems Physiology

Water Diuresis

Worksheet

1) 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

2) 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.

3) 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 Sex Body Weight

(kg) Volume of Water Ingested (litres)

A Control Male 82 0.984

B Exercise Male 76 0.912

4) 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.

5) For the subjects in your group plot graphs showing the effects of the various treatments on:

(a) Rate of urine production (ml/min) versus time. Plot the data for all subjects on the one graph. Make sure you identify each subject

(b) Urine osmolality versus time. There will be only one subject for this graph.

(c) Urine sodium concentration versus time. There will be 2 (or 3) subjects for this.

(d) 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 2.20 - 2.40 3.00 3.20 3.40 4.00

Time interval

(min) 20 - 20 20 20 20 20

Urine volume

(ml) 33 984 9.9 34 234 260 130

Urine flow

(ml/min) 1.65 - 0.50 1.70 11.70 13.00 6.50

Urine osmolality (mOsm/kg H2O) 600 - 600 200 200 200 0

Osmolar excretion rate (Osm/min) 282.6 - 297.0 340.0 2340 2600 0

Subject: X

Treatment: No treatment

Sample 1 Drink Sample 2 Sample 3 Sample 4 Sample 5 Sample 6

Time of day 2.20 - 2.40 3.00 3.20 3.40 4.00

Time interval (min) 20 - 20 20 20 20 20

Urine volume (ml) 33 984 9.9 34 234 260 130

Urine flow (ml/min) 1.65 - 0.5 1.70 11.70 13.00 6.50

Na+ conc'n (mmol/litre) 0.524 - 0.351 0.076 0.044 0.03 0.069

Na+ excretion rate (mol/min) 864.60 - 175.50 129.20 514.80 390.00 448.50

Cl- conc'n (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 2.20 - 2.40 3.00 3.20 3.40 4.00

Time interval (min) 20 - 20 20 20 20 20

Urine volume (ml) 40 912 21 92 162 55 24

Urine flow (ml/min) 2.00 - 1.05 4.60 8.10 2.75 1.20

Na+ conc'n (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- conc'n (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 9.46 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.

7) 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