Energy systems

Question 1

What is energy?

Answer 1

The property of matter and radiation which manifests as a capacity to perform work

Question 2

How does energy manifest in the human body?

Answer 2

Movement
Cell function
Maintenance

Question 3

*What is the function of myofibrilar ATPase?

Answer 3

Enzyme that catalyses this reaction
Enables the hydrolysation of ATP to ADP
Located in head of myosin molecule

Question 4

What are the 3 different sources for energy?

Answer 4

Anaerobic
ATP/PC system
Glycolytic
Aerobic
Mitochondrial respiration

Question 5

Describe the anaerobic pathways for ATP resynthesis

Answer 5

PCr + ADP + H+ -> ATP + Cr

Glucose + 2 ADP + 2Pi -> 2ATP + 2 H2O + 2 lactate

Question 6

What are the secondary anaerobic pathways

Answer 6

ADP + ADP -> ATP + AMP

AMP -> IMP + NH3 (deamination)

Question 7

Describe the aerobic pathway

Answer 7

Substrate + ADP + O2 -> ATP + CO2

substrates = CHO & FFA

Question 8

Describe the ATP/PC system

Answer 8

Acute response to maximal exercise
However phosphocreatine needs to be resynthesized so needs some energy for that process
High power - 9 mmolATP/kgDM/s
Low capacity - 55-95 mmolATP/kgDM

Question 9

Describe the rate of phosphocreatine synthesis under different conditions

Answer 9

Fast twitch fibres - slower replenishment of PCr

When not completely exhausted replenishment is quicker

Question 10

*Please explain the energy yield of the LA system

Answer 10

Glycolysis converts glucose to pyruvate
Using 2 ATP
However it yields 4 ATP as the process is run twice for each glucose molecule

Question 11

What is the power and capacity of the glycolytic system?

Answer 11

Medium power - 4.5 mmolATP/kgDM/s

Higher capcity - 190 - 300 mmolATP/kgDM

Question 12

Describe the fate of pyruvate

Answer 12

If no oxygen pyruvate becomes AcetylCoA with the help of NAD+ and pyruvate dehydrogenase (and byproduct O2 used in ETC)
If oxygen pyruvate becomes Lactate with the help of NADH and lactate dehydrogenase (NAD+ then goes back to help in glycolysis and delays fatigue)

Question 13

Describe the krebs cycle

Answer 13

Pyruvate enter the TCA cycle as ActeylCoA
TCA cycle occurs twice for each glucose molecule
Produces only 2 ATP but large amount of reduced coenzymes

Question 14

What happens in the electron transport chain?

Answer 14

There is a series of protein complexes embedded within the mitochondrial membranes
They capture electrons from NADH and FADH and transfer then through membranes
Transfer coupled with pumping of H+ ions to intermembrane space creates a gradient which is used to produce energy

Question 15

What is the actual ATP yield?

Answer 15

29.85 ATP/glucose

Question 16

Describe beta oxidation

Answer 16

95% of energy comes from fatty acid chains
16 C atoms combined with H oxidised to create C pairs which free NADH and FADH2 creating 27 ATP
C pairs form AcetylCoA which enter krebs cycle and produces 107ATP
22 ATP comes from glycerol

Question 17

*Please describe the fuel utilisation figure

Answer 17

Association between exercise intensity and fuel utilisation
At rest most energy comes from fat with minimal contributions of CHO
With increasing intensity CHO utilisation increase and fat reduces
Training and SNS activity may affect substrate utilisation

Question 18

Describe fuel selection during exercise

Answer 18

Rest; energy from plasma FFA and plasma glucose
40% VO2 max; mostly fat sources and FFA, with some plasma glucose and muscle glycogen
55% VO2 max; intensity increasing more use of muscle glycogen
75% VO2 max; fat oxidation reduced most of energy comes from muscle glycogen and plasma glucose

Question 19

Describe fuel selection and fitness levels

Answer 19

Untrained individuals have lower capacity of mobilising fat in order to produce energy
Glucose levels similar
Trained individuals used more fat to meet energy demands - using less of stored glycogen