Hormone messengers are independent of the nervous system, and take longer to cause an effect. Hormones are made by endocrine glands to control another part of the body. These hormones are secreted directly into the bloodstream. Many different hormones must be balanced one with another. Glands may react by secreting one hormone to shut down the production or effects of another.
Glands have the power to produce several different kinds of hormones at any time.
The liver also has the power to control an overabundance of some hormones in the blood. Endocrine glands include the gonads, pineal, pituitary, thyroid, parathyroid, thymus and adrenals. Beginning from the top down, here is a brief description of this fascinating set of internal controls which help the body perform at peak efficiency while adapting to change, whether internal or external. We begin at the center of the brain with the pineal gland, a pea-sized organ that is highly sensitive to light. Until recently, almost nothing was known about this gland.