Endocrine System

The endocrine system is the thermostat of the body, coordinating a complex weather station of glands and hormones. The endocrine glands, scattered throughout the body, include the two adrenal glands; the pancreas; the pituitary, parathyroid and thyroid glands; and the ovaries. All these glands work to regulate vital body functions such as height, weight, growth, metabolism, sexual development and fertility.

* The two adrenal glands, which sit like small pyramids on top of the kidneys, are famous for making the "fight or flight" hormone, adrenaline. They also influence blood sugar, blood volume and sexual development. One malfunction, Cushing''''s syndrome, can cause you to gain weight. (See "Adrenal Glands" on page 3.)

* The adrenal cortex produces a hormone called cortisol when you''''re under stress--and cortisol raises your blood pressure. (To chill out stress, see "Winding Down a Bit" on page 392.)

* The pancreas sits just behind the stomach, linked to the small intestine. It produces the hormone insulin--the chief wizard that turns our food molecules into invigorating fuel. When the pancreas falters, diabetes can be the result. (To lower your chances of adult-onset diabetes, see "Playing the Prevention Game" on page 307.)

* The four parathyroid glands, flanking your throat, control calcium balance in your blood. If your calcium levels fall, the glands release parathyroid hormone, which burglarizes your bones for the mineral. (For one more reason to get enough calcium, see "Hormones" on page 182.)

* The thyroid gland at the base of your neck releases the hormone thyroxine. It tells your body how fast to burn calories. If you''''re losing weight without really trying, your thyroid may be gushing out too much thyroxine. (See "Thyroid" on page 408.)

* The two almond-sized ovaries on either side of your womb secrete the Earth Mother sex hormone, estrogen. Among its many duties is protecting the bones from calcium loss. So when the ovaries retire at menopause, many women are faced with decisions about hormone replacement therapy. (To help you with your questions, read "The Big Decision" on page 231.)