Energy Metabolism Flashcards
1
Q
What is the difference between kcal and kJ?
A
- they are inequivalent units of measure used to express energy
2
Q
1 calorie =
A
4.184 joule
3
Q
4 steps of energy metabolism:
A
- food
- digested
- absorbed
- metabolized/oxidized
4
Q
Macronutrients are oxidized by creating _____, which is….
A
- ATP
- major storage form of molecular energy in our body
5
Q
When a molecule is oxidized, a significant portion of the release energy is salvaged as ____ ____ in the form of …..
A
- chemical energy
- new, high energy bonds, with the rest released in the form of heat
6
Q
The chemical energy is generally contained in ____ ____ ____ ____, chiefly those of _____.
A
- high energy phosphate bonds
- ATP
7
Q
In the 1950s, what did Rubner & Atwater find?
A
- metabolizable energy
- difference between the gross energy of consumed food and the energy present in feces and urine
8
Q
Metabolizable energy:
A
amount of fuel actually available to cells for conducting biological processes
9
Q
Atwater had begun to analyze the _____ and ____ ____ of food.
A
- composition
- energy content
10
Q
One of the largest and most comprehensible databases for energy metabolism is:
A
USDA National Nutrient Database
11
Q
Canada’s database:
A
Canadian Nutrient File
12
Q
PRO = ___ kcal/g
A
4
13
Q
CHO = ____ kcal/g
A
4
14
Q
FAT = ___ kcal/g
A
9
15
Q
3 components of total energy expenditure (TEE):
A
- resting metabolic rate
- activity thermogenesis
- thermic effect of food
16
Q
Expended energy reflects fuels metabolized for ….
A
- growth
- body maintenance needs
- PA
- pregnancy and lactation
- other processes
17
Q
Key determinants of activity EE:
A
- genetic traits
- age
- sex
- environmental stimuli
18
Q
Key determinants of thermal effect of food:
A
- diet composition
- age
- PA
- obesity
- insulin resistance
19
Q
Key determinants of resting metabolic rate:
A
- fat free mass
- fat mass
- sex
- age
- genetic traits
20
Q
RMR:
A
- resting metabolic rate
- energy required for the maintenance of normal body functions and homeostasis in resting conditions
21
Q
RMR accounts for ___% of TEE.
A
60-70
22
Q
Different ____ ____ have markedly different resting energy requirements.
A
body tissues
23
Q
Organs that have large metabolic demands:
A
- liver
- kidneys
- intestines
- brain
- heart
- these organs together: 10% of total body weight and 75% of RMR
24
Q
Adipose tissue EE:
A
- 20% of total body weight
- < 5% of RMR
25
Skeletal muscle EE:
- 40% of total body weight
| - 20% of RMR
26
RMR correlates closely with _____.
FFM
27
Although EE of metabolically active _____ is responsible for a large component of RMR, _____, which is composed primarily of ____ ____, accounts for most of the variability in EE between individuals.
- organs
- FFM
- skeletal muscle
28
Contrary to popular belief, people with obesity generally have a _____ absolute resting EE. Why?
- higher
- higher PA expenditure
- higher resting EE
- higher thermic effect of food
29
REE is linearly related to both ____ and ____.
- FFM
| - FM
30
People with obesity have higher ___ and ___.
- FFM
| - FM
31
FFM = ______ active tissues, contributes more to _____.
- metabolically
| - REE
32
2 components of activity thermogenesis (AT):
- exercise activity thermogenesis (EAT)
| - non-exercise activity thermogenesis (NEAT)
33
EAT:
EE of a planned, structured, and repetitive PA with the objective of improvement or maintenance of physical fitness
34
NEAT:
EE of any bodily movement produced by skeletal muscles
35
The most variable component of daily EE is...
AT
36
AT can vary from an average of ___% of the daily EE up to ____% in extreme conditions during heavy ____ training or competition.
- 30%
- 80%
- endurance
37
_____ is extremely important for the maintenance of the daily energy balance.
exercise
38
AT can be controlled ______.
voluntarily
39
_____ is very high in active individuals, where as _____ is very high in sedentary individuals.
- AT
| - RMR
40
However, in contrast to the predictions of the constrained EE model....
- exercise training does not lead to dec. REE under conditions of weight stability
- REE adjusted for body composition is not equal to between people with a wide range of PA levels
- exercise may increase the TEF
41
When PA increases via exercise, the non-PA components of EE.....
do not decrease as predicted by the constrained model
42
Increments in daily EE shortly after starting an ____ ____ can be greater than the expended energy cost of the exercise.
exercise program
43
As training progresses, daily EE does not _____ ____ (despite increasing volume and intensity) --> may be because of improvements in ____ _____ that decrease energy cost of exercise.
- increase linearly
| - biomechanical efficiency
44
Diets differing in ____ ____ could result in different responses on energy metabolism.
macronutrient distribution
45
Energy balance =
body weight maintenance
46
One of the first studies in dietary manipulation took place in _____.
1957
47
Weight loss in people with obesity was intimately related to _____ _____ of the diet.
macronutrient composition
48
Trends in CHO, FAT, and PRO intake:
- inc. energy CHO + dec. PRO, FAT = inc. obesity
| - 1% inc. protein = dec. 32 kcal CHO & dec. 51 kcal FAT
49
Increasing PRO composition of diet may facilitate ____ _____ _____.
reducing energy intake
50
Isocaloric diets differing in macronutrient composition may result in .... This over the long term will alter....
- preferential partitioning of energy storage
| - the proportions of FM and FFM during weight loss and weight gain
51
Dietary ____, in particular, is known to positively influence ___ during weight loss and weight gain.
- protein
| - FFM
52
Energy balance refers to the balance between...
EE (RMR, AT, TEF) and energy intake (Kcal, macronutrients)
53
Negative energy balance:
- EE > intake
| - weight loss
54
Positive energy balance:
- intake > expenditure
| - weight gain
55
RQ:
- respiratory quotient
- directly measured from tissues (invasive)
- provides meaningful information with respect to EE and substrate oxidation
56
RQ =
VCO2/VO2
57
RER:
- under steady-state conditions, we measure VO2 and VCO2 from the mouth (indirect calorimetry)
- predicts well what is happening at the cellular level (less invasive)
58
An RQ = 1.00 suggests....
- CHO is being oxidized
| - the amount of O2 required for the combustion of glucose equals the amount of CO2 produced
59
An RQ = 0.70 suggests....
- FAT is being oxidized
| - fatty acids are a much less oxidized fuel source (fewer O2 molecules)
60
An RQ for _____ is more complicated....
- protein
- metabolic oxidation of AA requires removing the N and some O2 and C as urea
- urea N represents a net loss of energy to the body: only the C chain can be oxidized in the body
61
An RQ of 0.82 suggests.....
PRO is being oxidized
62
If a truly accurate RQ is required, a correction has to be made by measuring the amount of ____ ___ _____ over a specific time period.
Urinary N excreted
63
For every 1g of N excreted:
- 5.912 L of O2 are consumed
| - 4.758 L of CO2 are produced
64
The amount of O2 and CO2 exchanged in the release of energy from ____ can be subtracted from....
- protein
| - the total amount of measured gaseous exchange
65
The RQ of an ordinary mixed diet consisting of CHO, PRO, and FAT is usually....
0.85
66
In clinical practice, an RER < 0.70 can indicate:
- hypoventilation
- underfeeding
- alkalosis
- ketosis
- low-carb diet
- high alcohol diet
67
In clinical practice, an RER > 1.00 can indicate:
- hyperventilation
- overfeeding
- acidosis
68
Once RER has been computed from gaseous exchange, the EE is calculated based on....
the caloric value of 1L of O2 and 1L of CO2, given various RERs
69
The amounts of ____ and ____ being oxidized in the production of these calories is also possible.
- CHO
| - FAT
70
Why is the oxidation of protein ignored in the determination of the non-protein RQ?
because under ordinary circumstances the contribution of protein to energy metabolism is so small
71
____ rather than _____ basal or REE has been the practice among clinicians since 1925.
- estimating
| - measuring
72
Estimations have been based on:
- body SA
- body weight
- calculations from regression equations that incorporate age, sex, weight, height
73
Estimates have been shown to correlate with measurements from ____ _____ and ____ ____ _____.
- indirect calorimetry
| - doubly labeled water
74
Commonly used equations to estimate REE in healthy adults:
- Mifflin-St Jeor
| - Harris-Benedict
75
Commonly used equation to estimate TEE in healthy, normal weight adults 19 years and older:
Dietary Reference Intakes (DRIs)
