Kidneys act as filters and help to clean the blood of all the waste materials.
One of the key substances the kidney filters is urea. Urea is a waste product
from the break down of amino acids. Proteins cannot be stored in the body,
so any excess is either converted into carbohydrates or fats. This occurs in
the liver and as a bi product the liver produces urea.
If urea remains in the body then it can be poisonous and therefore has to be
filtered out of the body.The kidneys also have a key role in controlling the ion
levels in the body. The levels of ions aer very important as they essentially
control the level of water. The ions determine how much water the cell holds
and therefore if the ion levels are not correct the water levels can also be
Therefore if the ion level is too high then, some of the ions are filtered then
removed, if the level of water is too low then ions are retained in order to
retain water as well.
The ultimate role of the kidneys is to control the levels of water in the body,
if there is too much water in the body then more is lost in urine, if there is
less water in the water then the urine is more concentrated with waste
materials and less water is present.