Page 34 - The Miracle of Hormones

THE MIRACLE OF HORMONES

This is very important because, if the amount of hormone secreted were
more or less than what is needed, the result would be quite undesirable.
If too little hormone is secreted, dwarfism occurs, and if too much is
secreted, gigantism is the result. 2
So, for this reason a very special system for regulating the amount of
this hormone secreted in the body has been created. The amount of this
hormone secreted is determined by the hypothalamus, which is recog-
nized as the director of the pituitary gland. When it is time for the growth
hormone to be secreted, it sends the "growth hormone-releasing hor-
mone" (GHRH) to the pituitary gland. And when too much growth hor-
mone has been released into the blood, the hypothalamus sends a
message (the somatostatin hormone) to the pituitary gland and slows
down the secretion of the growth hormone. 3
Yet how do the cells that compose the hypothalamus know how
much growth hormone there should be in the blood? How do they meas-
ure the amount of growth hormone in the blood and made a decision

Epiphyseal line

Periosteum
Every bone cell in
Secondary
the body knows ossification
where it will be, Ossifying centers Marrow
cavity
what shape it will cartilage
have, and how Epiphyseal plate
large it will grow. Artery
They obey without Artery
Cartilage
error the com-
mands they receive
from the growth Secondary Articular
hormone. This ossification cartilage
communication Diaphysis Bone Marrow center
cavity
among its cells al-
lows the body to
grow in proportion. Epiphysis

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