Water Diuresis and Urinalysis: Experiment and Results

Title
Student’s Name:
Student’s number:
Subject:
WATER DIURESIS AND URINALYSIS
Date of practical session

Aims
The experiment aimed at:
 Determining the osmotic regulation of the kidneys when it comes to maintaining a
balance of fluids in the body
 Studying the physical characteristics of urine and establishing if a urine sample is normal
Introduction
The human kidneys have a significant role to play in the human body as they aid in the
regulation of the volume of plasma, the osmolality, pH, ionic composition and even elimination
of waste products of metabolic processes. All these regulations work in harmony to ensure that
homeostasis is maintained in the body1. The main determinants of the composition of blood
include cellular metabolism, urinary output as well as the diet. To the tune of 180 liters of blood
plasma is filtered by the nephrons of the kidney in 24 hours through the glomeruli into the
tubules in which it undergoes selective processing by the tubular reabsorption and secretion.
The human body has up to 5 liters of blood circulating at any given time out of which twenty
percent which represents one liter of the blood circulates to the kidneys. The roles of the kidney
are the billions of the nephrons that they are composed of which serve to filter blood. Each of the
neurons of the kidney has renal corpuscle and renal tubules. In the renal corpuscles are the
Bowman’s capsule and glomerulus while in the renal tubules contains the loop of Henle,
proximal tubule, the distal convoluted tubules as well as the connecting tubules which connect
the collecting duct2.
There are two parts of the proximal tubule: proximal convoluted tubule and the proximal straight
tubule. The loop of Henle is subdivided into three main parts: a thin ascending limb, the
descending limb, and the thick ascending limb. The entry of blood is first through the afferent

arteriole then into the glomerulus and finally, it's filtered out to the Bowman's capsule. The
filtrate is referred to as the glomerular filtrate and is plasma that does not contain proteins.
Reabsorption and elimination of solutes, ions, and water take place in the kidneys. Whereas
reabsorption defines the movement of water, ions, and nutrients back to the blood through the
peritubular capillaries from the filtrate that is found in the tubules, a greater portion of it takes
place in the proximal convoluted tubule and some fraction in the distal convoluted tubule.
Three main hormones aid in the proper functioning of the kidneys: Anti-Diuretic Hormone,
Atrial Natriuretic Peptide, and Aldosterone3. Anti-Diuretic Hormone is termed as a
vasoconstrictor which raises the blood sugar levels and increases the reabsorption of water, urine
specific gravity, plasma volume as well as decreasing the flow rate of urine.
Stimulation of Anti-Diuretic Hormone targets the collecting duct and the proximal convoluted
tubule resulting into reabsorption of water. Aldosterone is generated in the adrenal cortex where
it stimulates Renin-Angiotensin-Aldosterone System upon a decrease in the volume, plasma
osmolality and pressure occurrence thereby resulting into a enhancement n the reabsorption of
sodium through the distal tubule4.
The role of this experimental study was to determine the kidneys' osmotic regulation when it
comes to maintaining a balance of fluids in the body as well as studying the various physical
characteristics of urine. Two subjects were chosen for the first study in which one consumed
fresh water and the other saline or salty water. The second part of the experiment involved
comparing the properties of urine from three different subjects against the normal characteristics
of urine.

Materials and Methods
Experimental Procedure for Part I
1. Every student was required to collect a morning sample of urine collected as soon as they
got out of bed and labeled it t=morning. Students selected as subject 1 or 2 not to pass
urine just before the experiment or take any caffeinated beverages.
Subject 1 would be undertaking the water test
Subject 2 would be undertaking the saline test.
2. Immediately upon arrival to the practical, Subject 1 and Subject 2 were required to
completely empty their bladder into the sterile collection container (graduated cylinder)
as soon as they arrive.
3. Record these measurements in the table below.
4. Subject 1 would drink 750 to 1000 ml of water quickly (within 5-10 minutes). Then
wait 15 minutes and collect a urine sample. Collect a further 2 urine samples at 15 minute
intervals over the next 45 minutes (i.e. t=15, t=30 and t=45). Ensure that the ‘recorder’
and subject are using the timer to keep an accurate measure of the timing5.
5. Subject 2 would drink 750 to 1000 ml of 0.9% (isotonic) saline quickly (within 5-10
minutes). Similar to the Subject 1, collect a urine sample at three 15 minute intervals over
the next 45 minutes (i.e. t=15, t=30 and t=45).
6. Wash down the area of the lab bench you are working on with a 70% ethanol solution.
Experimental Procedure for Part II
One strip was removed from bottle and cap replaced. Completely immerse reagent areas of the
strip in the sample and remove immediately.