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Nutrition & Metabolism > W2 - Energy > Flashcards

W2 - Energy Flashcards

1
Q

What does a kcal express?

A

Quantity of heat needed to raise the temp of 1kg of a substance by 1 degree celcius.

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2
Q

What does heat of combustion refer to?

A

Heat liberated by oxidising a specific food - representing foods total energy.

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3
Q

What are the 2 factors affecting energy release during combustion of a foods protein component?

A

Type of protein in food

Rel. N content of that protein

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4
Q

What influences the ultimate energy yield from the food macronutrients?

A

Efficiency of digestive processes

== Coefficient of digestibility

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5
Q

What can reduce the coefficient of digestibility

A

Dietary fibre

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6
Q

What is the concept of turnover based on?

A

1st law of thermodynamics

(Refers to the process that molecules are constantly degraded + restored).

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7
Q

List some common chemical intermediates

A

ATP

GTP

UTP

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8
Q

How much energy can you get from breaking off the phosphates from ATP?

A

24kJ of energy per mol of ATP

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9
Q

Hydrolysis of ATP

A

ATP + H20 – (ATPase) –> ADP + Pi + Energy

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10
Q

What is every cellular process going to use for energy?

A

Either:

ATP

GTP

UTP

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11
Q

Ways to get ATP from ADP + Pi

A

Oxidation of CHO or fats

PCr system

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12
Q

What are the 3 fundamental types in which athletic activities can be grouped into?

A

Power

Speed

Endurance

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13
Q

Storage form for power activity

A

ATP

PCr

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14
Q

Storage form for speed activity

A

Predominantly glycogen + glucose

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15
Q

Storage form for endurance activity

A

Glycogen

Glucose

Lipids

aa (if need be)

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16
Q

Time to depletion for ATP

A

2s

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17
Q

Time to depletion for PCr

A

8s

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18
Q

Time to depletion for glycogen –> lactate

A

6 min

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19
Q

Time to depletion for glycogen –> CO2 + H20

A

100 min

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20
Q

Time to depletion for Fat

A

days

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21
Q

Concentration (mmol/kg dm) for ATP

A

24

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22
Q

Concentration (mmol/kg dm) for PCr

A

80

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23
Q

Concentration (mmol/kg dm) for Glycogen

A

300

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24
Q

Concentration (mmol/kg dm) for fat

A

Large

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25
Q

What is the resting concentration of PCr?

mmol / kgmuscle

A

30 mmol / kgmuscle

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26
Q

PCr reaction equation

A

PCr + ADP –(creatine kinase)–> ATP + Cr

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27
Q

PCr breakdown reaction

A

PCr –> Cr + Pi + Energy

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28
Q

Use of Pi from PCr breakdown to regenerate ATP

A

ADP + Pi + Energy –> ATP

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29
Q

Is PCr a direct energy form that can be used by the body?

A

NO

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30
Q

After PCr system what’s the 2nd immediate energy source?

A

Myokinase reaction

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31
Q

Equation for the myokinase reaction

A

2ADP –(Adenylate kinase(myokinase))–> ATP + AMP

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32
Q

What do the myokinase reaction + the breakdown of PCr do together?

A

Work closely to maintain intracellular ATP levels

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33
Q

REGULATION

ATP

A

They’re poor signals for control of metabolic rate

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34
Q

REGULATION

What do changes in AMP signal?

A

They’re powerful signals for metabolic control.

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35
Q

Why is AMP important?

A

It’s presence is a profound signal for activating mechanisms of ADP restoration to ATP

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36
Q

What are AMP concentrations important for?

A

Metabolic regulators of what’s going on in the cell.

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37
Q

What determines the energy charge of the cell?

A

Rel. changes in adenylate

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38
Q

What is an indicator of the capacity of a cell to do work?

A

Energy charge

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39
Q

How is energy charge calculated?

A

(ATP + half the conc. of ADP) / (ATP + ADP + AMP)

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40
Q

What is the energy charge when all the adenylate pool is in the form of ATP?

A

1.0

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41
Q

What is the energy charge when all the ATP is hydrolysed to AMP (only theoretically possible)

A

0

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42
Q

What is the normal charge of a cell?

A

0.9-0.95

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43
Q

How is AMP prevented from accumulating?

A

By being converted to IMP

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44
Q

Reaction for AMP to IMP

A

AMP + H –(AMP deaminase)–> IMP + NH4+

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45
Q

What does the reaction of AMP to IMP result in?

A

⬆️ energy charge

46
Q

What does the AMP deaminase do when converting AMP to IMP

A

Remove amine group

47
Q

AMP –> IMP

IMP follows 1 of 2 pathways what are the possible conversions of it?

A

To inosine or hypoxanthine

48
Q

Which is more mobile in the cell? PCr or ATP?

49
Q

What would happen to the inosine + hypoxanthine that would be bad?

A

Leave muscle = NET loss of adenine nucleotides = losing potential energy

50
Q

What is the option to prevent NET loss of adenine nucleotides from IMP when exercise stops

A

Convert IMP back into AMP

51
Q

Energy is needed to convert IMP back into AMP.

Where does this come from?

52
Q

What reduces the amount of AMP at a specific time, therefore allowing exercise to continue?

A

Purine Nucleotide cycle

53
Q

What is the “new concept” of contribution of energy pathways

A

Overlap of contribution

== All your energy pathways are used around the start of exercise.

54
Q

Which pathway contributes the most at the start of exercise + which follow?

A

ATP

PCr

Anaerobic

Aerobic

55
Q

Power output in a Wingate test

A

PCr 23-28%

Glycolysis 49-56%

Oxidative metabolism 16-18%

56
Q

Can fuel sources be depleted?

Give examples

A

YES

i.e PCr, CHO + fat

57
Q

Can you deplete your energy sources?

Give examples

A

NO

i.e ATP, GTP + UTP

58
Q

What are the 4 types of energetic efficiency?

A

Gross efficiency

Net efficiency

Work efficiency

Delta efficiency

59
Q

How is gross efficiency (%) calculated?

A

(Work accomplished / EE) x 100

60
Q

How is net efficiency (%) calculated?

A

(Work accomplished / energy expended - REE) x 100

61
Q

How is work efficiency (%) calculated?

A

(Work accomplished / energy expended - EE in unloaded) x 100

62
Q

How is delta efficiency (%) calculated?

A

(change in work accomplished / change in EE) x 100

63
Q

What does a low N content in a protein mean for heat produced?

A

Less heat is produced

64
Q

How many kcal are in 1g of alcohol?

65
Q

Digestibility % for 1g of CHO

66
Q

Digestibility % for 1g of fat

67
Q

Digestibility % for 1g of protein

68
Q

Digestibility % for 1g of alcohol

69
Q

What % of digestibility are vegetable proteins?

70
Q

What % of digestibility are animal proteins?

71
Q

What % of energy out is basal metabolism?

72
Q

What % of energy out is thermogenesis?

73
Q

What % of energy out is PA?

74
Q

What does TDEE stand for?

A

Total daily energy expenditure

75
Q

What does ADMR stand for?

A

Avg daily metabolic rate

76
Q

What does BMR stand for?

A

Basal metabolic rate

77
Q

What does RMR stand for?

A

Resting metabolic rate

78
Q

What does TEF stand for?

A

Thermic effect of food

79
Q

What does DIT stand for?

A

Diet induced thermogenesis

80
Q

What does TEE stand for?

A

Thermic effect of exercise

81
Q

What does EEA stand for?

A

Energy expenditure for PA

82
Q

Energy use of organs at rest from lowest to highest

A

Heart - 7%

Kidneys - 10%

Skeletal muscle - 18%

Brain - 19%

Liver - 27%

83
Q

Describe a direct calorimetry chamber

A

Small insulated chamber w/ adequate ventilation.

84
Q

What can be found at the top of a direct calorimetry chamber?

A

Coils through which H20 flows through to absorb the heat.

85
Q

What happens to the CO2 + H20 in the direct calorimetry chamber?

A

Filtered out + air is recirculated.

86
Q

Disadvantages to direct calorimetry chamber

A

Expensive

Not practical - can’t just move chamber around

Need specialised people to run it

87
Q

Is heat exchange measured in a respiration chamber?

88
Q

What does a respiration chamber measure?

A

O2 in + CO2 out

89
Q

How long do respiration chamber tests take?

What else do we know?

A

Hours to days

Food intake can be accurately measured

Urine + faeces can be collected

90
Q

Why might urine + faeces be collected in respiration chambers?

A

To measure energy + N balance

91
Q

Disadvantages to respiration chambers

A

Highly trained needed

Expensive

Boring

92
Q

What are the 2 ways of measuring indirect calorimetry

A

Douglas bag technique

Breath by breath systems

93
Q

Douglas bag technique

A

1 sample of expired air in allotted time

Haldane transformation

94
Q

Breath by breath systems

A

Immediate analysis

Continuous measurement

95
Q

What gives you an idea of whether its fat or CHO you’re burning by looking at a set of results collected from indirect calorimetry?

A

RQ (Respiratory Quotient)

96
Q

What is the RQ?

A

Ratio of CO2 production to O2 consumption

97
Q

What is doubly labeled water

A

H20 where H + O2 have been partly or completely replaced (labelled).

W/ an uncommon isotope of these elements for tracing purposes.

98
Q

How is the hydrogen from doubly labelled water excreted?

A

Independent of metabolic rate

99
Q

How is the oxygen from doubly labelled water excreted?

A

As CO2 + H20

100
Q

What do you look at when using the doubly labelled water method?

A

At the differences between heavy H + O2 + compare to normal H + O2.

101
Q

How much can a single dose of the doubly labelled water cost?

102
Q

What does CO2 production tell you when using doubly labelled H20?

A

Difference in H + O isotopes excretion

More O = ⬆️ EE.

103
Q

What can the energy cost of running be roughly estimated to?

A

1 kcal / kg BM / km

BM = Body mass

104
Q

Side-effects to athletes on the lower limits of energy intake at around 1000-1500kcal / day with lots of exercise

A

Loss of muscle mass

Anaemia

Secondary amenorrhea

⬇️ body mass

Low bone mineral density

105
Q

What are the different ways of measuring energy intake?

A

24h recall

3 day food diary

7 day food diary

Food freq questionnaire

Diet history

106
Q

Can energy balance be assessed accurately?

A

Most will under report around 20%

Results in certain populations are unreliable

107
Q

When is it best to measure resting metabolic rate?

A

After a 12hr fast

108
Q

What must the subject not do prior to their RMR being measured?

A

No PA or smoke for up to 24hrs before

109
Q

When is BMR usually measured?

A

After an overnight stay in clinic or lab where research is being completed

110
Q

What factors could influence metabolic rate?

A

Illness

Age

Gender

Muscle:fat

Hormone function

PA levels

Nutrition & Metabolism (17 decks)

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