Page 72 - The Miracle of Hormones

THE MIRACLE OF HORMONES

Hypothalamus detects
low level of thyroid
hormone in the blood.
Hypothalamus

Blood vessel

Hypothalamus secretes a
releasing factor to the
anterior pituitary

Anterior pituitary releas-
es more thyroid-stimulat-
ing hormone (TSH) into
Anterior pituitary the body's circulatory
system.

Target tissues Thyroid
gland

Thyroid produces thyrox-
ine until sufficient levels
are reached

When enough thyroid hormone has been produced, the hypothalamus
stops the production of the thyroid-releasing hormone.

that the thyroid gland must be activated and immediately sends a com-
mand (the TSH—Thyroid Stimulating Hormone) to the thyroid gland.

The thyroid gland, as the last point in this chain of command, immedi-
ately secretes thyroxine in compliance and distributes it throughout the
whole body by way of the blood.

70