Metabolizmi

Metabolizmi, or metabolism, refers to the set of chemical reactions that sustain life in all living organisms. It encompasses energy production from nutrients (catabolism) and the biosynthesis of cellular components (anabolism). Through catabolic pathways such as glycolysis, pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation, carbohydrates, fats, and proteins are converted into adenosine triphosphate (ATP) and other energy carriers, with byproducts like carbon dioxide and water.

Anabolic pathways build macromolecules—proteins, nucleic acids, polysaccharides, and lipids—using energy and reducing power, supporting growth, maintenance, and repair. These processes are highly integrated, with the same metabolites shuttling between pathways as needed.

Regulation of metabolism is achieved through enzymes and hormones, including insulin, glucagon, adrenaline, and thyroid hormones. Cells adjust metabolic flux in response to nutrient availability, energy needs, and circadian rhythms, employing feedback inhibition and alternate routes such as gluconeogenesis when glucose is scarce.

Metabolic activity varies across tissues. The liver, muscle, adipose tissue, and the gut coordinate to maintain blood glucose, lipid balance, and amino acid pools. Basal metabolic rate—energy expended at rest—depends on age, sex, body composition, and activity, and can be estimated by indirect calorimetry.

Clinical relevance includes metabolic disorders such as diabetes mellitus, obesity, dyslipidemias, and inherited metabolic diseases, which reflect disruptions in specific pathways and have wide-ranging health impacts.

Metabolizmi thus describes a dynamic, integrated system that converts food to usable energy and building blocks, enabling growth, adaptation, and homeostasis.