<P> A hormone ( from the Greek participle `` ὁρμῶ '' , `` to set in motion , urge on '' ) is any member of a class of signaling molecules produced by glands in multicellular organisms that are transported by the circulatory system to target distant organs to regulate physiology and behaviour . Hormones have diverse chemical structures , mainly of 3 classes : eicosanoids , steroids , and amino acid / protein derivatives ( amines , peptides , and proteins ) . The glands that secrete hormones comprise the endocrine signaling system . The term hormone is sometimes extended to include chemicals produced by cells that affect the same cell ( autocrine or intracrine signalling ) or nearby cells ( paracrine signalling ) . </P>
<P> A hormone ( from the Greek participle `` ὁρμῶ '' , `` to set in motion , urge on '' ) is any member of a class of signaling molecules produced by glands in multicellular organisms that are transported by the circulatory system to target distant organs to regulate physiology and behaviour . Hormones have diverse chemical structures , mainly of 3 classes : eicosanoids , steroids , and amino acid / protein derivatives ( amines , peptides , and proteins ) . The glands that secrete hormones comprise the endocrine signaling system . The term hormone is sometimes extended to include chemicals produced by cells that affect the same cell ( autocrine or intracrine signalling ) or nearby cells ( paracrine signalling ) . </P>
a natural chemical which controls a specific body function is called a ( n )
a natural chemical which controls a specific body function is called a ( n )
hormone
hormone