W2 - Energy Flashcards
(110 cards)
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.
2
Q
What does heat of combustion refer to?
A
Heat liberated by oxidising a specific food - representing foods total energy.
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
4
Q
What influences the ultimate energy yield from the food macronutrients?
A
Efficiency of digestive processes
== Coefficient of digestibility
5
Q
What can reduce the coefficient of digestibility
A
Dietary fibre
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).
7
Q
List some common chemical intermediates
A
ATP
GTP
UTP
8
Q
How much energy can you get from breaking off the phosphates from ATP?
A
24kJ of energy per mol of ATP
9
Q
Hydrolysis of ATP
A
ATP + H20 – (ATPase) –> ADP + Pi + Energy
10
Q
What is every cellular process going to use for energy?
A
Either:
ATP
GTP
UTP
11
Q
Ways to get ATP from ADP + Pi
A
Oxidation of CHO or fats
PCr system
12
Q
What are the 3 fundamental types in which athletic activities can be grouped into?
A
Power
Speed
Endurance
13
Q
Storage form for power activity
A
ATP
PCr
14
Q
Storage form for speed activity
A
Predominantly glycogen + glucose
15
Q
Storage form for endurance activity
A
Glycogen
Glucose
Lipids
aa (if need be)
16
Q
Time to depletion for ATP
A
2s
17
Q
Time to depletion for PCr
A
8s
18
Q
Time to depletion for glycogen –> lactate
A
6 min
19
Q
Time to depletion for glycogen –> CO2 + H20
A
100 min
20
Q
Time to depletion for Fat
A
days
21
Q
Concentration (mmol/kg dm) for ATP
A
24
22
Q
Concentration (mmol/kg dm) for PCr
A
80
23
Q
Concentration (mmol/kg dm) for Glycogen
A
300
24
Q
Concentration (mmol/kg dm) for fat
A
Large
25
What is the resting concentration of PCr?
| mmol / kgmuscle
30 mmol / kgmuscle
26
PCr reaction equation
PCr + ADP --(creatine kinase)--> ATP + Cr
27
PCr breakdown reaction
PCr --> Cr + Pi + Energy
28
Use of Pi from PCr breakdown to regenerate ATP
ADP + Pi + Energy --> ATP
29
Is PCr a direct energy form that can be used by the body?
NO
30
After PCr system what's the 2nd immediate energy source?
Myokinase reaction
31
Equation for the myokinase reaction
2ADP --(Adenylate kinase(myokinase))--> ATP + AMP
32
What do the myokinase reaction + the breakdown of PCr do together?
Work closely to maintain intracellular ATP levels
33
REGULATION
ATP
They're poor signals for control of metabolic rate
34
REGULATION
What do changes in AMP signal?
They're powerful signals for metabolic control.
35
Why is AMP important?
It's presence is a profound signal for activating mechanisms of ADP restoration to ATP
36
What are AMP concentrations important for?
Metabolic regulators of what's going on in the cell.
37
What determines the energy charge of the cell?
Rel. changes in adenylate
38
What is an indicator of the capacity of a cell to do work?
Energy charge
39
How is energy charge calculated?
(ATP + half the conc. of ADP) / (ATP + ADP + AMP)
40
What is the energy charge when all the adenylate pool is in the form of ATP?
1.0
41
What is the energy charge when all the ATP is hydrolysed to AMP (only theoretically possible)
0
42
What is the normal charge of a cell?
0.9-0.95
43
How is AMP prevented from accumulating?
By being converted to IMP
44
Reaction for AMP to IMP
AMP + H --(AMP deaminase)--> IMP + NH4+
45
What does the reaction of AMP to IMP result in?
⬆️ energy charge
46
What does the AMP deaminase do when converting AMP to IMP
Remove amine group
47
AMP --> IMP
IMP follows 1 of 2 pathways what are the possible conversions of it?
To inosine or hypoxanthine
48
Which is more mobile in the cell? PCr or ATP?
PCr
49
What would happen to the inosine + hypoxanthine that would be bad?
Leave muscle = NET loss of adenine nucleotides = losing potential energy
50
What is the option to prevent NET loss of adenine nucleotides from IMP when exercise stops
Convert IMP back into AMP
51
Energy is needed to convert IMP back into AMP.
Where does this come from?
GTP
52
What reduces the amount of AMP at a specific time, therefore allowing exercise to continue?
Purine Nucleotide cycle
53
What is the "new concept" of contribution of energy pathways
Overlap of contribution
== All your energy pathways are used around the start of exercise.
54
Which pathway contributes the most at the start of exercise + which follow?
ATP
PCr
Anaerobic
Aerobic
55
Power output in a Wingate test
PCr 23-28%
Glycolysis 49-56%
Oxidative metabolism 16-18%
56
Can fuel sources be depleted?
Give examples
YES
i.e PCr, CHO + fat
57
Can you deplete your energy sources?
Give examples
NO
i.e ATP, GTP + UTP
58
What are the 4 types of energetic efficiency?
Gross efficiency
Net efficiency
Work efficiency
Delta efficiency
59
How is gross efficiency (%) calculated?
(Work accomplished / EE) x 100
60
How is net efficiency (%) calculated?
(Work accomplished / energy expended - REE) x 100
61
How is work efficiency (%) calculated?
(Work accomplished / energy expended - EE in unloaded) x 100
62
How is delta efficiency (%) calculated?
(change in work accomplished / change in EE) x 100
63
What does a low N content in a protein mean for heat produced?
Less heat is produced
64
How many kcal are in 1g of alcohol?
7
65
Digestibility % for 1g of CHO
97
66
Digestibility % for 1g of fat
95
67
Digestibility % for 1g of protein
92
68
Digestibility % for 1g of alcohol
100
69
What % of digestibility are vegetable proteins?
78%
70
What % of digestibility are animal proteins?
97%
71
What % of energy out is basal metabolism?
60-75%
72
What % of energy out is thermogenesis?
10%
73
What % of energy out is PA?
15-30%
74
What does TDEE stand for?
Total daily energy expenditure
75
What does ADMR stand for?
Avg daily metabolic rate
76
What does BMR stand for?
Basal metabolic rate
77
What does RMR stand for?
Resting metabolic rate
78
What does TEF stand for?
Thermic effect of food
79
What does DIT stand for?
Diet induced thermogenesis
80
What does TEE stand for?
Thermic effect of exercise
81
What does EEA stand for?
Energy expenditure for PA
82
Energy use of organs at rest from lowest to highest
Heart - 7%
Kidneys - 10%
Skeletal muscle - 18%
Brain - 19%
Liver - 27%
83
Describe a direct calorimetry chamber
Small insulated chamber w/ adequate ventilation.
84
What can be found at the top of a direct calorimetry chamber?
Coils through which H20 flows through to absorb the heat.
85
What happens to the CO2 + H20 in the direct calorimetry chamber?
Filtered out + air is recirculated.
86
Disadvantages to direct calorimetry chamber
Expensive
Not practical - can't just move chamber around
Need specialised people to run it
87
Is heat exchange measured in a respiration chamber?
NO
88
What does a respiration chamber measure?
O2 in + CO2 out
89
How long do respiration chamber tests take?
What else do we know?
Hours to days
Food intake can be accurately measured
Urine + faeces can be collected
90
Why might urine + faeces be collected in respiration chambers?
To measure energy + N balance
91
Disadvantages to respiration chambers
Highly trained needed
Expensive
Boring
92
What are the 2 ways of measuring indirect calorimetry
Douglas bag technique
Breath by breath systems
93
Douglas bag technique
1 sample of expired air in allotted time
Haldane transformation
94
Breath by breath systems
Immediate analysis
Continuous measurement
95
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?
RQ (Respiratory Quotient)
96
What is the RQ?
Ratio of CO2 production to O2 consumption
97
What is doubly labeled water
H20 where H + O2 have been partly or completely replaced (labelled).
W/ an uncommon isotope of these elements for tracing purposes.
98
How is the hydrogen from doubly labelled water excreted?
Independent of metabolic rate
99
How is the oxygen from doubly labelled water excreted?
As CO2 + H20
100
What do you look at when using the doubly labelled water method?
At the differences between heavy H + O2 + compare to normal H + O2.
101
How much can a single dose of the doubly labelled water cost?
3-3,500
102
What does CO2 production tell you when using doubly labelled H20?
Difference in H + O isotopes excretion
More O = ⬆️ EE.
103
What can the energy cost of running be roughly estimated to?
1 kcal / kg BM / km
BM = Body mass
104
Side-effects to athletes on the lower limits of energy intake at around 1000-1500kcal / day with lots of exercise
Loss of muscle mass
Anaemia
Secondary amenorrhea
⬇️ body mass
Low bone mineral density
105
What are the different ways of measuring energy intake?
24h recall
3 day food diary
7 day food diary
Food freq questionnaire
Diet history
106
Can energy balance be assessed accurately?
Most will under report around 20%
Results in certain populations are unreliable
107
When is it best to measure resting metabolic rate?
After a 12hr fast
108
What must the subject not do prior to their RMR being measured?
No PA or smoke for up to 24hrs before
109
When is BMR usually measured?
After an overnight stay in clinic or lab where research is being completed
110
What factors could influence metabolic rate?
Illness
Age
Gender
Muscle:fat
Hormone function
PA levels
