Metabolic processes are all the chemical reactions that occur within an organism to maintain life, including both breaking down substances for energy (catabolism) and building new cells and tissues (anabolism).
Anabolism: The synthesis of complex molecules in living organisms from simpler ones together with the storage of energy; constructive metabolism.
Catabolism: The breakdown of complex molecules in living organisms to form simpler ones, along with the release of energy; destructive metabolism.
Homeostasis: The tendency towards a relatively stable equilibrium between interdependent elements, especially as maintained by physiological processes.