The Endocrine System

• The Endocrine System


  This is one of the body's information systems; it instructs glands to release hormones directly into the bloodstream. These hormones are then carried towards target organs in the body.

  • A gland is an organ in the body that makes hormones
  • A hormone is a chemical substance that circulates in the bloodstream and only affects target organs. They are produced in large quantities and have powerful effects but disappear quickly.
• Most hormones affect cells in several organs or throughout the entire body; for example, the thyroid gland produces the hormone thyroxine. This hormone affects cells in the heart (increases heart rate) and it also affects cells throughout the body, increasing metabolic rates (the chemical processes taking place in the cells.) This in turn affects growth rates.
• The major gland of the endocrine system is the pituitary gland; it is located in the brain and is often referred to as the master glad because it controls the release of hormones from all the other endocrine glands in the body.