what is catabolism

Catabolism is the set of metabolic pathways that breaks down molecules into smaller units that are either oxidized to release energy or used in other anabolic reactions. It is the destructive branch of metabolism that results in the release of energy. Catabolism breaks down large, complex molecules into smaller ones, such as glucose, amino acids, and fatty acids, which form the building blocks for anabolism. Examples of catabolic processes include glycolysis, the citric acid cycle, the breakdown of muscle protein to use amino acids as substrates for gluconeogenesis, the breakdown of fat in adipose tissue to fatty acids, and oxidative deamination of neurotransmitters by monoamine oxidase. Catabolic hormones, such as adrenaline, cortisol, cytokines, and glucagon, are associated with the breakdown of molecules for energy. In contrast, anabolism is the constructive branch of metabolism that involves the synthesis of complex molecules from simpler ones.