Glands and hormones
The endocrine system is composed of a series of hormonal organs and glands that produce and secrete hormones that the body uses for a wide range of functions. They control many different bodily functions, including breathing, metabolism, reproduction, movement, sexual development and growth.
Hormones are chemicals produced by specific organs and glands and are sent through the bloodstream to the various tissues in the body. They give the tissues signals telling them what they are supposed to do. When the glands do not produce the right amount of hormones, diseases develop that can affect many aspects of life.
Hormone production is usually controlled by a kind of “thermostat”. If there is too little of a given hormone in the blood, the producing gland will be stimulated (usually by another hormone) to make more. If hormone levels are too high, stimulation will decrease. This can be compared to the heating in our homes. If it is too cold, the thermostat will turn the heat on and if the temperature is just right, the heat will turn off.
The stimulating hormone is in turn often controlled by another hormone (or hormones). This creates a network of hormones that we refer to as a “hormone axis”, such as the “thyroid axis” or the “adrenal axis”.