Some glands such as the thyroid, parathyroid, and the islet cells of the pancreas, secrete primarily a single hormone which has a relatively specific function. As examples, the thyroid hormone regulates oxidative metabolism, and the islet-cell hormone assists in glucose metabolism. In both cases, the adrenal promotes the general body functions that facilitate such reactions. The pituitary, a small tissue mass located at the base of the brain below the hypothalamus, is the most important and complex endocrine gland. It secretes at least eight hormones that orchestrate the response of the other glands and that produce effects on general body functions such as growth and water balance.
Pituitary activity varies dynamically depend stream hormone levels.
On the other hand, the brain itself might be sensitive to alterations in the electromagnetic environment. Such a sensitivity could result in activation of a number of hormonal systems by virtue of the direct connection between the brain and the pituitary. If an EMF constituted a threat to the integrity of the organism, the pituitary-adrenal stress response system would be called into action. Indeed, the bulk of the endocrine system studies have involved the pituitary-adrenal system. These studies illustrate the difficulty in establishing the precise causal chain of events in the functioning of a hormone system, as would be required to determine the level at which the EMF acts in the first instance.