The internal environment of the body is mainly regulate~ by the lungs and the kidneys, in addition to the gastrointestinal tract and sweat glands. The lungs control the concentration of oxygen and carbon dioxide whereas the kidneys. regulate the optimum
chemical composition the body fluid~. .
The main function 0 the kidney is the formation and excretion of urin~. They also .
pr?duce '~onia, which.hel s in the' neutralization_?f the a~ids. Th~ kidn
Y through' the
unne excrete. _ "
. 1. Extra water and salts from the body so as to maintain normal horn stasis between
the extra-cellular and intra-cellular fluids,
2. Acids or bases, to maintain the normal acid-base balance,
. 3. Waste products,.and
.4. Toxic and detoxified substances from the body.'
The composition of urine, -even in a perfectly normal individual, varies considerably during the every day life. Therefore, for a reasonably accurate analysis, whether
qualitative or quantitative, it is necessary to collect 24-hours urine. Samples collected ,over
short periods show varying results as compared to a 24-hours sample '-,
Number of diseases can be diagnosed by the examination of the urine~ For routine examination the urine should be voided or passed in a clean. vessel.
The urine is examined in THREE stages:
1. Physical Examination,
2. Chemical Examination, and
3. Microscopic' Examination.
. The physical examination of urine is conducted to note the following
characteristics of the urine:
4. . Volume,
. 5. Specific gravity, and
6. pH or Reaction.
Normal' urine, almost always, is perfectly clear and transparent when voided.
A faint cloudy flocculance appears on standing, principally due to the nucleoproteins or ,mucoproteins;which are present only in traces, along with some epithelial cells.
Turbidity may appear in an alkaline or n~utral urine due to the presence of
mucus and amorphous phosphate crystals. Opalescent white colour of the urine may be due to
, ~. .' .
the presence of pus - or bacteria. Addition of acetic acid or warming does liot clear the
turbidity -due to pus, bacteria or blood. .
Freshly voided urine.has an aromatic odour, which may be modified due to z
presence of certain substances in the diet. For example, the unpleasant odour of meu..~i mercaptan -is given by the urine on taking asparagus iil the diet. In ketosis, there 'is a ftm..J aroma due to the presence of large amounts of acetone in the urine, which some, times aid m the