CHARACTERISTICS OF HORMONES -
(1) They are regulatory chemicals that control and coordinate functions of different body organs.
(2) Hormones are formed by ductless or endocrine glands.
(3) Hormones are poured into circulatory system in which they are soluble and carried to target cells.
(4) They function as chemical messengers or information molecules.
(5) Hormones generally function away from the area of their formation.
(6) They are effective in very low concentration of picograms or micrograms. The concentration of testosterone is 30 -100 ng/ml.
(7) Hormone molecules are small in size.
(8) They belong to diverse categories of proteins, peptides, amino acid derivatives, amines, steroids, etc.
(9) Hormone molecules get attached to the membranes of target cells at specific points having receptors for inward passage or reaction.
(10) They inhibit or stimulate specific processes in the target cells.
(11) Hormones do not provide raw materials or energy. They simply start certain reactions and are consumed in the process. (12) Hormones are formed in response to specific stimuli.
(13) They may be formed in the inactive state e.g., pro-insulin.
14) Hormones control most actiyities like membrane permeability, cell division, cell growth, cell differentiation, regeneration, reproductive activity, production of enzymes and metabolism, ion and water balance of the body, adaptations and emergencies etc.