Hormones are secretions from specific cells or glands in the body called endocrine glands. Hormones are carried by blood to target organs. These are also called ductless glands because their secretions are poured directly into the blood and not through ducts. Certain hormones are produced by other glands or body parts also, for example, the stomach and the duodenum.

Nature and Function of Hormones

  1. Hormones are secreted from their source directly into the blood. Blood carries the hormone to the target cells which respond to it.
  2. Hormones regulate the physiological processes.
  3. They are produced in very small quantities and are biologically very active. For example, adrenaline is active even at a concentration of 1 in 300 million parts.
  4. Their excess and deficiency, both, cause serious disorders.
  5. Chemically, the hormones may be water-soluble proteins (peptides)glycoproteins and amines or lipid-soluble steroids.
  6. The extra hormones are not stored in the body and are excreted out.