What are Hormones?

Hormones are chemical messengers that are produced in one part of the body and have an effect on another part.

Hormones switch body processes on and off, and they regulate most of the body's activity. The nervous system also helps in these processes, giving pared instructions along the nerves. The body's endocrine system uses hormones which work much more slowly. The majority of hormones are carried around the body in the bloodstream, reaching all the major organs and tissues.

The body has more than 30 different hormones. They are mostly produced in organs called endocrine glands.

These glands discharge the hormones directly into the bloodstream. Other types of glands pass their secretions through ducts to the point where they are needed. Endocrine glands are found in the head, neck and torso. The amount of hormones in the body is regulated by a feedback system. This means that once hormones are produced, the body measures them and once they have reached the required level, their production is switched off again. Sometimes this mechanism does not work properly and over or underactive glands such as the thyroid can produce illness.