Metabolica

Metabolica, or metabolism, refers to the set of chemical reactions that occur within living organisms to sustain life. In Spanish and Italian, the term metabolica is used; in English, metabolism. These reactions convert nutrients into energy and building blocks for growth, repair, and maintenance, and facilitate the elimination of waste products.

Metabolism is commonly divided into catabolism, the breaking down of molecules to harvest energy, and anabolism, the synthesis of complex molecules from simpler ones. Most processes are organized into metabolic pathways, linked through common intermediates such as ATP, NADH, and acetyl-CoA.

Key pathways include glycolysis, the conversion of glucose to pyruvate with net ATP and NADH production; pyruvate oxidation and the citric acid cycle; and oxidative phosphorylation, which uses the electron transport chain to generate most cellular ATP. In addition, lipid metabolism includes beta-oxidation and lipogenesis; amino acid metabolism handles deamination and synthesis; and gluconeogenesis maintains blood glucose during fasting.

Metabolic activity is tightly regulated by enzymes and by hormonal and allosteric signals. Hormones such as insulin, glucagon, adrenaline, and thyroid hormones modulate pathways according to energy needs and nutrient availability. Genetic factors and environmental conditions also influence metabolic rate.

Understanding metabolism is central to medicine, nutrition, and physiology. Abnormal metabolism underlies many diseases, including diabetes mellitus, obesity, metabolic syndrome, and inherited disorders of metabolism. Metabolic rate can vary with age, sex, body composition, and activity, and is often assessed by indirect calorimetry or metabolic testing.