Metabolism

• Metabolism: complex, interactive set of chemical processes that make life possible. It is how our body uses food once it has been ingested
• Catabolism: breakdown of large and complex molecules into smaller simpler ones
• Anabolism: building of simpler molecules into complex ones
• Catabolic reactions release energy stored in organic molecule like carbohydrates, lipids and proteins
• The chemical energy in food cannot be used directly for chemical reactions, it must first be transfered to high energy molecules to form ATP
• ATP is the energy currency of the cell and stores energy which powers anabolic reactions and other functions
• Anabolic reactions need more energy than they produce like when combining amino acids into proteins
• Metabolic rate: the amount of energy released in the body by catabolism
• Basal metabolic rate (BMR): rate of energy spent under basal conditions (awake. but resting in a comfortable state)
• Total metabolic rate: amount of energy expended by the body in a given time, with exercise taken into consideration
• Factors affecting BMR:

  • size
  • sex
  • age
  • body temperature
  • drugs
  • lactation and pregnancy