A.2.3.1 (2) Aerobic and Anaerobic energy systems

Anaerobic energy systems

1. ATP-PC (Phosphocreatine) System

   • Found in the sarcoplasm

   • Activated by an increase in ADP

   • When creatine kinase breaks down the phosphate, creatine energy is released, which is used to resynthesize ATP.

   • The energy lasts up to 10 seconds = available rapidly as it is easy to break down.

   • Overall, PC is broken down to creatine, freeing the phosphate and energy used to convert ADP to ATP.

2. Lactic Acid System

   • Overall, glycogen is broken down into glucose, pyruvic acid, and lactic acid. The energy given off is used to produce ATP.

   • Other names: Anaerobic glycolysis

   • Found in the sarcoplasm

   • Fuel used: carbohydrate (glucose). Carbohydrates are digested into glucose, travel through the bloodstream to the liver and muscles and are stored as glycogen

   • Enzyme: phosphofructokinase

   • up to 3 mins of exercise

   • Note - Phosphorylation: the addition of phosphate to an organic compound

Aerobic energy systems

There are three stages:

• Stage 1: Aerobic glycolysis - Glucose is broken down into pyruvate/pyruvic acid, and due to the presence of oxygen, lactic acid is not produced

  • Happens in the sarcoplasm

  • Produced 2 ATP

• Stage 2: Krebs Cycle - Pyruvate moves to the mitochondria and mixes with CoA to create acetyl-Coa. Chemical reactions occur in the mitochondria, which break down acetyl-Coa to produce 2 ATP, CO₂ and electron carriers

  • Hydrogen atoms are removed, and hydrogen carriers then transport electrons to the electron transport chain.

• Stage 3: Electron Transport Chain - water is produced

  • 34 ATP molecules are produced