A2 Anatomy and Physiology - Energy Systems

Question 1

Describe how the ATP-PC system works

Answer 1

Anaerobic process - resynthesises ATP. Enzyme creatine kinase detects high ADP - breaks down phosphocreatine in muscles to PC + creatine, releasing energy

1PC makes 1ATP

Question 2

Advantages and disadvantages of the ATP-PC system

Answer 2

Advantages:
- ATP re-synthesised rapidly
- PC stores replenished quickly (50% - 30s and 100% - 3mins)
- No fatiguing by-products
- ATP-PC can be extended by creatine supplementation
Disadvantages:
- Limited supply of PC in muscles (8s)
- Only 1ATP re-synthesised for 1PC
- PC re-synthesis only in presence of O2

Question 3

Describe how the Anaerobic Glycolytic System Works

Answer 3

Glycogen broken down to glucose by glycogen phosphorylase. Glucose broken down to pyruvic acid by phosphofructokinase in sarcoplasm (glycolysis). Pyruvic acid broken down to lactic acid by lactate dehydrogenase.
Net gain of 2ATP molecules

Question 4

Advantages and disadvantages of Anaerobic Glycolytic System

Answer 4

Advantages:
- ATP re-synthesised quickly and lasts longer than ATP-PC system
- Presence of O2 - lactic acid converted back to liver glycogen or used as fuel through oxidation to CO2 and H2O
- Can be used for sprint finish
Disadvantages:
- Lactic acid as by-product - denatures enzymes - slows down reactions
- Small amount of energy released from glycogen under anaerobic conditions

Question 5

Describe how the Aerobic System Works (Glycolysis)

Answer 5

• In sarcoplasm
• Glycogen broken down to glucose by glycogen phosphorylase
• Glucose broken down to pyr