Water Diuresis in Man

1) What does the word 'diuresis refer to?

Diuresis is the increase in the rate of production of urine in the kidney and usually an increase in release

of urine from the body. It could be due to a large consumption of water, diabetes mellitus/insipidus which

causes polyuria or possibly diuretic drugs.

2) What are the particular characteristics of a 'water diuresis'?

Water diuresis is a result of an ingestion of water that is greater than what is 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). (2 marks)

Subject

Treatment

Sex

Body Weight

(kg) Volume of Water Ingested (litres)

A Control Na+ Analyser A F 48 576

B Exercise Na+ Analyser B F 66 792

C ADH- Ion Analyser F 70 840

D Control- Osmometer F 44 528

4) Complete the data tables on the next two pages. There should be one table completed for each subject in your group. Each subject will have data for urine Sodium Ion concentration or osmolality. If there were only 3 subjects in your group, write 'no subject available' across the last data table.

(12 marks)

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.

(c) Urine sodium concentration versus time.

(d) Sodium excretion rate versus time.

For graphs (b) to (d) there will be a variable number of subjects depending on whether sodium concentration or osmolality was determined.

Attach these four graphs to this Worksheet. (4 marks for each graph = total of 16 marks)

(a) Graph a: Urine Production (ml/min) Vs. Time(min)