The Metabolism

The Metabolism

  • represents the continuous exchange of substances and energy between the body and external environment, all the biochemical and energy transformations that occurs in the living body tissue
  • the metabolism begins with the ingestion of food and ends with the excretion of the faeces
  • stages: digestive, cellular, excretory
  • digestive phase
    • hydrolytic fragmentation of organic macromolecules from food molecules and transforms them into simple molecules, absorbable in the body (glucose, fatty acids, amino acids, glycerol)
  • cellular stage
    • the food principles suffer numerous biochemical transformations, representing the intermediary metabolism. It is the exchange of substance and energy between the cells and the internal environment
  • the metabolic reactions inside the cells are
    • anabolic
    • synthesis of cell constituents or reserve. Through these reactions takes place the continuous renewing of the old cell structures, the active substances are synthetized (enzymes, hormones), in order to ensure growth and cell proliferation, the cells are loaded with reserve nutrients. Requires energy.
    • catabolic: splitting up until the substances till the final product: unsuitable substances. These reactions generate energy by complete metabolism of the intermediate product by oxidation-reduction reactions. Part of the reaction takes place in the Krebs’s cycle, and others in the cellular respiratory chain.
  • energetic stage
    • energy is released from the cells by oxidation reactions of lipids and carbohydrates, and also of proteins sometimes. This energy is stored initially in the form of chemical ATP bonds (the primary source of energy for each cell).
    • cells convert the substances’ chemical energy into mechanical energy, osmotic energy, electrical energy, caloric energy
  • BMR is the metabolic base rate
    • is the rate at which energy is consumed in a state of rest
    • average value is 1.1 calories / hour / kg
    • the higher BMR value increases, the easier it is to lose weight
    • BMR value decreases at the beginning of a hypocaloric diet because the body lowers the metabolism in order to conserve energy (that explains the stagnation during the diet)
    • BMR value increases with exercise, because they continue to burn calories even after the training stops
    • exercises are the only way to increase BMR, because they increase muscle mass and boost metabolism
    • a low BMR does not cause obesity
  • metabolic balance
    • represents the value of assimilation and desasimilation ratio
    • can be positive when the anabolism is greater than catabolism
    • negative-when anabolism is less than catabolism