ABSTRACT
The endocrine, or ductless, glands secrete metabolically active chemical mediators into the vascular circulation, which in turn, are distributed to all organs.* These hormones function as chemical mediators between endocrine glands and speciÞc effector organs, regulating metabolic processes and physiological growth and development. In contrast to the neurochemicals of the nervous system, endocrine hormones affect all body cells, require longer onset of action, have prolonged duration, and are delivered systemically rather than locally in response to nerve impulses.
