SUBSTRATE SUPPLY FOR ENERGY PROCESSES IN CHILDREN

Аннотация

The use of substrates as energy sources changes during the first months of a child's life. Since anaerobic glycolysis predominates in newborns, which provides relatively little energy, and energy expenditure per unit of body mass is very high, the newborn utilizes energy reserves accumulated in utero during the first days after birth to sustain vital processes. The presence of these reserves determines the effectiveness of the child's adaptation to extrauterine life. Keywords: newborns, energy, glucose, substrate, glycolysis, fatty acids. Objective of the Study: Analysis of changes in substrate supply for energy processes in children. Discussion and Research Results In the first hours of life, the newborn uses glycogen as an endogenous energy source. However, at birth, the child has insufficient glycogen reserves. At the moment of birth, the blood sugar level of the newborn corresponds to that of the mother. Stress hormones released during labor rapidly deplete glycogen stores in the liver. Within 2–3 hours after birth, blood glucose levels in newborns decrease to hypoglycemic levels. Under these conditions, non-esterified fatty acids (NEFA) become the primary energy source. The cooling of the newborn’s body, which occurs after birth due to transitioning from the maternal environment to a new habitat, triggers the release of hormones (thyroxine, norepinephrine in brown adipose tissue, and glucagon during hypoglycemia), which activate the breakdown of triglycerides to produce fatty acids. Выпуск журнала №-20 Часть–3_ Февраль –2025 119 MODERN EDUCATION AND DEVELOPMENT The concentration of NEFA in the blood increases and is subsequently used for energy production. Since proteins are virtually not used as an energy source during the first days after birth, and carbohydrate reserves are extremely low, NEFA become the primary endogenous energy source for newborns. Lipolysis reaches its peak on the 3rd–4th day after birth, coinciding with the period of maximum weight loss in newborns. All tissues, except the brain and erythrocytes, consume NEFA. Simultaneously, tissues increase their use of ketone bodies, which also serve as an energy resource. From the second week of life, blood glucose levels in newborns gradually rise, while NEFA levels decrease; however, NEFA levels remain higher than in older children until about three months of age. Under these conditions, when hypoglycemia prevents tissues from effectively using blood glucose and intense lipolysis depletes energy reserves in the newborn's body, the infant remains at the threshold of energy balance during the first week of life.