Page 24 - The Miracle of Hormones

THE MIRACLE OF HORMONES

In some cases the hypothalamus, in order to intervene in the activity
of the cells, uses two hormones that it has secreted itself. To store these hor-
mones, it first sends them to the pituitary gland, then, when required, it en-
sures that they are secreted by the pituitary gland. These hormones are:
❏ Vasopressin (an antidiuretic, i.e., water retaining, hormone)
❏ Oxytocin
These two hormone molecules produced by the hypothalamus are
very small. One of them is only three amino acids large. The hypothala-
mus hormones are distinguished from other hormones not only by being
small; they also differ from other hormones by the distance they cover in
the body. Hormones generally travel a long distance from the hormonal
gland where they were produced to the designated organ. However, the
hypothalamus hormones reach the pituitary gland after passing through
only a capillary vessel a few millimeters thick. They never enter the gen-
eral circulatory system.
The hypothalamus produces the hormones that activate the pituitary
gland, and when necessary, it also produces hormones that stop the pitui-
tary gland at the appropriate time from secreting a certain hormone. In
this way, it has complete control over the activity of the pituitary gland.

The Conductor of the Hormone Orchestra:

The Pituitary Gland

The pituitary gland is a small, pink piece of flesh the size of a chick-
pea, weighing half a gram and connected to the hypothalamus in the
brain by a stalk. Thanks to this connection, it takes orders directly from
the hypothalamus to produce the required hormones.
This pea-sized pituitary gland has such a great influence on the
human body and performs such wonderful functions that it has been the
subject of scientific enquiry for years (and still is). This small piece of
flesh has won much respect in the scientific world. The pituitary gland
has also earned some admiration because of its extraordinary character-

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