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The Endocrine
System
The endocrine system and the nervous system both
regulate functions in an animal's body. The nervous system works on a
short time scale and the endocrine system works on a long time
scale.
Endocrine glands secrete chemical substances,
called hormones, into the bloodstream. The hormones travel
around the body and bind to cells that have receptors for them on
their cell membranes. These cells are referred to as target
cells for that hormone. Once the hormone binds to its receptor,
it causes some change in the activity of the cell.
 | feedback loop - Many endocrine glands
operate on the basis of a feedback loop that is much like a
thermostat operating a heater. When the hormone secreted by one
endocrine gland stimulates another endocrine gland to secrete a
hormone, the second hormone often suppresses production of the
first hormone like the heat from a heater turns off a
thermostat.
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| Major endocrine glands
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