A hormone is a chemical substance produced by an animal or plant (yes even plants!) which acts as a "chemical messenger." Hormones act to help different parts of an organism to function in a coordinated way. Typically, hormones are formed in one part of an organism, and their effect occurs in a different area. The word hormone is derived from Greek and means, "to set in motion."
It was not until the early 1900's that the existence of these substances became known. Since then, over 30 human hormones have been identified, and we have developed the ability to "extract" them from tissues and synthesize them in the lab. In humans, most hormones are produced by certain glands called endocrine glands.
Doctors that specialize in the evaluation and treatment of hormone conditions are called endocrinologists.
In humans and animals, hormones control a number of bodily functions including growth, development, and reproduction. In plants, hormones mainly regulate growth. Decreased production of these chemical messengers can lead to serious diseases and even death.
Among the many functions that these chemicals regulate are;
- Metabolism growth
- Sexual function & reproduction
- Production of various blood components
- Reaction to stress
- Regulation of other hormones