Energy Systems

Question 1

what is adenosine triphosphate? (3)

Answer 1

• the only source of energy the body uses for all bodily functions and activities (movements)
• when it is used for energy production, it MUST BE REPLENISHED
• the body will either do this aerobically or anaerobically

Question 2

how exactly does ATP create energy? (2)

Answer 2

• the ATP molecule is broken down into ADP + Pi
• the action of breaking down and splitting one phosphate off creates the “free energy”

Question 3

why does ATP need to be replenished? (3)

Answer 3

• after being broken down, it is no longer ATP and therefore no longer an energy source
• it is now adenosine diphosphate
• the body will work continually to resynthesise ATP as fast as is required through the energy systems

Question 4

what are the three energy systems?

Answer 4

1. ATP-PC
   (alactic system)
2. ANAEROBIC GLYCOLYSIS
   (lactic acid system)
3. AEROBIC GLYCOLYSIS

Question 5

ATP-PC / ALACTIC SYSTEM (4)

Answer 5

• ATP and creatine phosphate are present in very small amounts in the muscle cells
• oxygen is not required for the process
• no lactic acid is produced in the process

predominantly used in: maximum intensity activities that last no longer than 10 seconds

Question 6

how does the ATP-PC system work? (4)

Answer 6

• phosphate creatine (PC) is another compound stored in the muscle
• creatine kinase detects high levels of ADP after the ATP has been broken down
• the PC is then broken down to release energy
• this energy is used to help ADP combine with the extra phosphate

Question 7

ANAEROBIC GLYCOLYSIS (3)

Answer 7

• uses carbohydrates stored in the muscles as glycogen
• lactic acid is produced as an end product
• predominantly used in: high intensity activities that last approximately 3 minutes but it peaks at 1 minute

Question 8

AEROBIC GLYCOLYSIS (5)

Answer 8

• uses carbohydrates (glycogen/glucose) and fats to replenish ATP
• energy production takes longer but can continue for a longer duration
• oxygen is required
• no lactic acid is produced
• predominantly used in: medium to low intensity activities

Question 9

how does the ANAEROBIC GLYCOLYSIS system work? (5)

Answer 9

• the glycogen stored in skeletal muscle cells and the liver is broken down into glucose
• glucose is then broken down into pyruvic acid/2 pyruvate
• this reaction also produces energy
• the energy is then used to replenish ATP by helping to reconnect the ADP and the PHOSPHATE that was left from the original breakdown of ATP
• 2 mol. of ATP is created
  1 mol. of glucose = 2 mol. of
  ATP

Question 10

how is “lactic acid” produced through anaerobic glycolysis? (3)

Answer 10

• the pyruvic acid is broken down by the enzyme LDH into “lactic acid”
• this is essentially just LACTATE and HYDROGEN IONS
• it’s the hydrogen ions that cause an increase in blood acidity

Question 11

how does AEROBIC LIPOLYSIS work? (4)

Answer 11

• fats are broken down into glycerol and free fatty acids
• these are then broken down into ACETYL COENZYME A, which again is the entry molecule for the KREBS CYCLE
• the H ions produced then go into the ELECTRON TRANSPORT SYSTEM where 147 ATP are produced
• this process requires approximately 15% more oxygen than glycolysis in order to break lipids down

Question 12

how does the AEROBIC GLYCOLYSIS system work? (6)

Answer 12

• begins the same way as anaerobic glycolysis
• instead, the pyruvic acid is oxidised to become ACETYL COENZYME A
• this is the entry molecule for the KREBS CYCLE
• which releases energy as 2 ATP and also produces the waste products carbon dioxide and hydrogen ions
• the hydrogen ions then enter the ELECTRON TRANSPORT CHAIN where they are oxidised
• this produces water and carbon dioxide as waste products along with 34 ATP

Question 13

what is beta oxidation?

Answer 13

the process by which fatty acids are broken down in the mitochondria to generate acetyl coenzyme a.

Question 14

what is the energy continuum?

Answer 14

• the interchanging of the energy systems during exercise

Question 15

which three factors decide what the predominant energy system will be?

Answer 15

1. INTENSITY
2. DURATION
3. FITNESS LEVELS OF THE PERFORMER

Question 16

what is the predominant energy system used at rest?

Answer 16

the aerobic system

Question 17

advantages (4) and disadvantages (3) of the ATP-PC system

Answer 17

ADVANTAGES
- replenishes ATP rapidly
-readily accessible, making it highly suitable for maximal activities
- fast recovery rate - PC stores back to around 98% after 3 minutes of rest
- oxygen isn’t needed

DISADVANTAGES
- low ATP yield to PCr - 1 mol of PCr makes 1 mol. of ATP (most inefficient)
- only lasts 8-12 seconds
- body needs to rely on the other systems after this system has been exhausted

Question 18

advantages (4) and disadvantages (3) of the anaerobic glycolysis system

Answer 18

ADVANTAGES
- creates two ATP for every one glucose molecule
- oxygen is not needed
- performer can last up to 3 minutes in this system
- helps sustain high intensity activity

DISADVANTAGES
- creates the hydrogen ions that cause an increase in blood acidity and therefore muscle fatigue
- peaks at 1 minute but can not be sustained
- reliant on carbohydrate feedings to restore glucose

Question 19

advantages (3) and disadvantages (3) of the aerobic system

Answer 19

ADVANTAGES
- most efficient system (energy yield is 38 ATP per 1 glucose molecule)
- no fatiguing by-products
- utilises three substrates (carbohydrates, fats, and proteins)

DISADVANTAGES
- replenishes ATP the slowest
- needs to be a sufficient amount of oxygen available for the aerobic process to occur
- compared to glycogen/glucose, break down of fats requires 15% more oxygen