A hormone may br defined as a specific product of an endocrine gland secreted into the blood which carries it to some part of the body where it produces a definite physiological effect. This effect may be either excitatory or inhibitory in its action. Thus, hormones are not only the "chemical messengers" that pass from the glands via the blood stream to the target organ or some process; but they are important regulating substances that control virtually every aspect of the metabolism in living cells. There are also chemical coordinators other than hormones, such as CO2 and other metabolites.
Posted by orchid101
on April 23, 2013 at 12:43 PM (Answer #1)