4.4. Aerobic System

Question 1

What happens in stage 1 (aerobic glycolysis)?

Answer 1

• Glycogen is broken down into glucose by GPP
• Glucose is broken down into pyruvic acid by PFK
• Pyruvic acid combines with coenzyme A to produce acetyl CoA and 2 ATP are also produced
• The presence of o2 prevents the accumulation of lactic acid

Question 2

What happens in stage 2 (Kreb’s Cycle)?

Answer 2

• The Acetyl CoA from stage 1 combines with Oxaloacetic acid and enters the Kreb’s cycle to form citric acid
• Co2 is produced and 2 ATP are formed.
• It’s an oxidative reaction because hydrogen atoms are lost and transferred to stage 3
• Oxaloacetic acid is regenerated and the cycle repeats

Question 3

What happens in stage 3 (electron transport chain)?

Answer 3

• The hydrogen atoms bind with NAD and FAD to form NADH and FADH.
• These molecules are carried down the ETC which splits hydrogen into ions (H+) and electrons (H-).
• Hydrogen ions are oxidised and removed as H2O (H+ combines with o2)
• The splitting of H+ and H- provides sufficient energy to resynthesise 34 ATP molecules.

Question 4

What is the overall net production of ATP from one cycle of the aerobic system?

Answer 4

38 ATP
1:38

Question 5

Site of reaction for aerobic glycolysis

Answer 5

muscle sarcoplasm

Question 6

Type of reaction for aerobic glycolysis

Answer 6

aerobic

Question 7

Chemical fuel for aerobic glycolysis

Answer 7

glycogen/ glucose/ FFAs

Question 8

Controlling enzymes for aerobic glycolysis

Answer 8

GPP
PFK

Question 9

Recovery process for aerobic glycolysis

Answer 9

lactacid
varies from 1-24 hrs

Question 10

By products of aerobic glycolysis

Answer 10

none

Question 11

Yield of aerobic glycolysis

Answer 11

2 ATP
1:2

Question 12

Site of reaction for the Kreb’s Cycle

Answer 12

mitochondrial matrix

Question 13

Type of reaction for Kreb’s Cycle

Answer 13

aerobic

Question 14

Chemical fuel for Kreb’s Cycle

Answer 14

glycogen/ glucose/ FFAs

Question 15

Controlling enzymes for Kreb’s Cycle

Answer 15

Acetyl CoA

Question 16

Recovery process for Kreb’s Cycle

Answer 16

lactacid
varies from 1-24 hrs

Question 17

By products of Kreb’s Cycle

Answer 17

Co2
easily removed

Question 18

Duration of the aerobic system

Answer 18

180 secs to 2+ hrs

Question 19

Intensity of the aerobic system

Answer 19

60-85%
varies

Question 20

Yield of Kreb’s Cycle

Answer 20

2 ATP
1:2

Question 21

Site of reaction of ETC

Answer 21

mitochondrial cristae

Question 22

Type of reaction of ETC

Answer 22

aerobic

Question 23

Chemical fuel of ETC

Answer 23

glycogen/ glucose/ FFAs

Question 24

Controlling enzymes of ETC

Answer 24

NAD/ FAD

Question 25

Recovery process of ETC

Answer 25

lactacid
varies from 1-24 hrs

Question 26

By products of ETC

Answer 26

H2O
easily removed

Question 27

Yield of ETC

Answer 27

34 ATP
1:34

Question 28

Adaptations of aerobic system to training

Answer 28

• Increases stores of muscle liver glycogen, mobilisation of aerobic enzymes and earlier use of FFAs
• Aerobic threshold is prolonged and OBLA is delayed = quicker/ more efficient recovery

Question 29

Advantages of aerobic system

Answer 29

• Large potential glycogen and FFAs stores available as efficient energy fuel
• Efficient ATP resynthesis when good oxygen supply
• Large ATP resynthesis -1 glucose molecule: 38 ATP
• Provides energy for low/ moderate intensity exercise and high duration exercise
• No fatiguing products - co2 and h2o easily removed

Question 30

Disadvantages of aerobic system

Answer 30

• Slower rate of ATP resynthesis
• Requires constant o2 supply (and 15% more when breaking FFAs down)
• Complex series of reactions = slower reaction/ recovery
• Cannot resynthesise ATP at start of exercise due to initial delay of o2 from the cardiovascular system
• Limited energy for ATP during high intensity, short duration work