Page 103 - The Miracle of Hormones

The Adrenal Glands

aldosterone is a finely designed solution for meet-
ing these two needs at the same time. If the quan-
tity of sodium in the blood increases, the fluid
level in the blood also rises with it. This is because
molecules of water have a tendency to go where
sodium is high.
Here is where we see the excellence of the de-
sign of aldosterone. On the one hand, it increases
the amount of sodium; on the other, it uses the
capacity of sodium to absorb fluid. When the
blood level of sodium falls, aldosterone warns the
cells in the tiny tubes of the kidneys. These cells
intercept the sodium ions in the urine and reab-
sorb them. This causes the sodium ions to enter
the cells forming the tiny tubes, and from there
they are released again into the blood.
In this way, the amount of sodium is raised,
the ion balance is maintained, the amount of fluid
in the blood is increased, and blood pressure is re-
stored to its normal level. When the sodium ions
in the tiny tubes of the kidneys are restored, potas-
sium ions (K+) are secreted from the blood to the urine because the pro-
portion of sodium and potassium in the blood must be at a very
particular rate. The mineral proportion is very important to ensure the
proper acid-base balance in the fluid inside and outside the cells, and for
the proper functioning of the nervous system.
Aldosterone is produced in the exterior portion of the adrenal gland.
The cells in this portion have never seen the cells in the depths of the kid-
neys (and there is no possibility for them to encounter them). How is it that
these cells know how to produce the right hormone for the reabsorption of
sodium and the release of potassium? How does the adrenal gland know
how to balance electrolytes and reduce the blood pressure? Most people
are unaware that such ions exist in their own bodies.

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