Energy Systems

Question 1

How does the body produce energy to contract our muscles?

Answer 1

• Body converts energy from food into energy for muscle contractions in order to produce movement
• E.G. shotput/100m sprint - energy needed quickly
• E.G. marathons - energy needed for long durations

Question 2

Duration/Intensity of ATP-PC

Answer 2

• Fuel = phosphocreatine
• Reaction occurs in sarcoplasm
• Stored ATP-PC lasts 2-3s of work
• Lasts 10s, but predominant for 1-5s
• After 30s, 50% is replenished, 3-4mins, 100% is replenished
• Used for max intensity efforts
• ATP yield: 1:1 - 1 molecule of ATP for every 1 PC
• E.G weightlifting/shotput

Question 3

Duration/Intensity of Anaerobic Glycolytic

Answer 3

• Fuel = glycogen
• Reaction occurs in sarcoplasm
• Lasts between 10s - 3mins, predominant for 1min
• Results in lactate and H+ ions - produces fatigue if not oxidised
• Used for high intensity efforts
• Also used for repeated max intensity efforts w/ little recovery time
• ATP yield: 2:1 - 2 molecules of ATP for 1 molecule of glycogen
• E.G. 400m sprint/hurdles

Question 4

Duration/Intensity of Aerobic

Answer 4

• Fuel = glycogen/triglycerides
• Predominant for 30s onwards
• Fatigue occurs when fuels are depleted
• Results in production of C02, H2O and heat
• Used for long durations, sub max intensity efforts
• 38:1 - 38 molecules of ATP for 1 molecule of glycogen/triglycerides
• E.G. cycling/rowing

Question 5

Breakdown and Resynthesis of ATP
How does it work to provide energy?

Answer 5

• Only usable form of energy in the body
• Adenosine triphosphate consists of one molecule of adenosine and 3 phosphates
• Energy that’s stored there is released by breaking the bonds down
• Enzymes are used to break it down - ATPase breaks down ATP leaving ADP and one inorganic phosphate (Pi)
• Body has to constantly revuild ATP by converting the ADP and Pi back into ATP
• Resynthesis of ATP can be done through 3 chemical reactions in the muscles: ATP-PC/Anaerobic Glycolytic/Aerobic systems
• Chemical reactions are fueled either by food of phosphocreatine

Question 6

What are the advantages of ATP-PC system?

Answer 6

• Energy can be resynthesised quickly
• PC stores resynthesised quickly (30s = 50%, 3m = 100%)
• No fatiguing by products
• Possible to extend time it’s used for through creatine supplementation

Question 7

What are the disadvantages of ATP-PC system?

Answer 7

• Limited supply of PC in muscles - only 10s
• Only 1 mole of ATP can be resynthesied for every mole of 1 PC (low ATP yield)
• PC resynthesis can only take place in the presence of O2

Question 8

How does the anaerobic glycolytic work to provide energy?

Answer 8

• When PC stores are low, the enzyme phosphorylase is actovated to breakdown glycogen into glucose
• Anaerobic glycolysis occurs - the break down into pyruvic acid by the enzyme PFK whihc takes place in the sarcoplasm where O2 isn’t available
• Pyruvic acid is further broken down into lactic acid through the enzyme LDH
• During anaerobic glycolysis, energy is released to allow ATP to resynthesise
• Net result = 2:1

Question 9

What are the advantages of anaerobic glycolytic system

Answer 9

• ATP can be resynthesised quickly due to few chemical reactions - lasts longer than ATP-PC
• In presence of O2, lactic acid can be converted back into liver glycogen or used as a fuel through oxidisation fo CO2 and water
• Can be used for high intensity

Question 10

What are the disadvantages of anaerobic glycolytic system

Answer 10

• Lactic acid is produced as a by product
• Only small amount of energy released from glycogen under anaerobic conditions (5% compared to 95% for aerobic)

Question 11

How does the aerobic system work to provide energy?

Answer 11

• Glucose is broken down into pyruvic acid through process of glyocolysis in the sarcoplasm - 2 ATP formed
• Pyruvic acid is oxideised into 2 acetyl groups: coenzyme A carries it into the Krebs Cycle
• 2 acetyl groups diffuse into matrix of mitochondria
• Acetyl groups cmobine with oxaloacetic acid = forms citric acid by ‘oxidative carboxylation’
• This produces C, H and 2 ATP molecules
• Hydrogen is carried to the electron transport chain by hydrogen carriers (NADH/FADH)
• Hydrogen splits into H ions and electrons are charged w/ potential energy
• H ions are oxidised to form water while electrons provide energy to resynthesise 34 ATP

Question 12

What are the advantages of the aerobic system

Answer 12

• High ATP yield: 36:1
• No fatiguing by products
• Lots of glycogen/triglyceride stores - exercise can last long

Question 13

What are the disadvantages of aerobic system

Answer 13

• Cannot be used straight away - takes time for enough O2 to be available to meet demands of activity and ensure glycogen/fatty acids are completely broken down
• Fatty acid transportation to muscles is low and needs 15% more O2 to be broken down than glycogen

Question 14

What is beta oxidation?

Answer 14

• Stored fats are broken down into glycerol + free fatty acids for transportation by blood
• Fatty acids undergo process called beta oxidation where they’re converted into acetyle coenzyme A - the entry molecule for Krebs Cycle
• Fat metabolism follows same path as glyocogen metabolism
• More ATP can be created from 1 molecue of fatty acids than 1 molecule of glucose
• In long duration/low intensity, fatty acids will be predominant energy source but depends on fitness