ATP/PC system

• Plants


  Convert light into stored chemical energy
• Humans


  Obtain energy via consumption of plants or animals that eat these plants
• Energy


  Stored as ATP (Adenosine triphosphate)
• ATP


  • Stored in muscle sarcoplasm
  • Provides kinetic energy for muscles to apply force to participate in physical activity
• ATP


  Adenosine, 3 phosphates held by high energy bonds
• ATP breakdown


  1. ATPase breaks down bond between last 2 phosphates

  2. Exothermic reaction

  3. Leaves ADP (adenosine diphosphate)
• Importance of ATP


  • Only usable source of energy that muscles can utilise
  • If no ATP, muscle fatigue
• ATP


  • Can be broken down and stored where needed
  • Stores limited amount, enough to supply 2-3 seconds of muscular work
• ATP resynthesis


  Energy required to rebuild bond between 2 phosphates
• Energy systems


  • ATP/PC System
  • Glycolytic System
  • Aerobic System
• ATP/PC System


  1. When ATP levels fall and ADP levels increase, this stimulates release of enzyme creatine kinase

  2. Creatine kinase breaks down PC bond, releasing energy (exothermic)

  3. Energy can't be used for muscular work, instead coupled to resynthesize ATP back to ATP

  4. ATP/PC doesn't require O2 so is anaerobic

  5. Occurs in sarcoplasm

  6. PC broken down by creatine kinase

  7. Only 1 ATP resynthesized, so can only supply PC resynthesis and ATP resynthesis for 3-10 secs