The rate of metabolism can be increased by exercise by elevated body temperature, as in a high fever, which can more than double the metabolic rate by hormonal activity, such as that of thyroxine, insulin, and epinephrine and by specific dynamic action that occurs following the ingestion of a meal. In the catabolic, or destructive, phase these organized substances are reconverted into simpler compounds, with the release of energy necessary for the proper functioning of the body cells. The anabolic, or constructive, phase is concerned with the conversion of simpler compounds derived from the nutrients into living, organized substances that the body cells can use. There are two phases of metabolism: the anabolic and the catabolic phases. Essentially these processes are concerned with the disposition of the nutrients absorbed into the blood following digestion.
the sum of the physical and chemical processes by which living organized substance is built up and maintained ( anabolism), and by which large molecules are broken down into smaller molecules to make energy available to the organism ( catabolism).
