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Flashcards in Energy Metabolism Deck (75)
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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
  1. food
  2. digested
  3. absorbed
  4. 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
Q

Skeletal muscle EE:

A
  • 40% of total body weight

- 20% of RMR

26
Q

RMR correlates closely with _____.

A

FFM

27
Q

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.

A
  • organs
  • FFM
  • skeletal muscle
28
Q

Contrary to popular belief, people with obesity generally have a _____ absolute resting EE. Why?

A
  • higher
  • higher PA expenditure
  • higher resting EE
  • higher thermic effect of food
29
Q

REE is linearly related to both ____ and ____.

A
  • FFM

- FM

30
Q

People with obesity have higher ___ and ___.

A
  • FFM

- FM

31
Q

FFM = ______ active tissues, contributes more to _____.

A
  • metabolically

- REE

32
Q

2 components of activity thermogenesis (AT):

A
  • exercise activity thermogenesis (EAT)

- non-exercise activity thermogenesis (NEAT)

33
Q

EAT:

A

EE of a planned, structured, and repetitive PA with the objective of improvement or maintenance of physical fitness

34
Q

NEAT:

A

EE of any bodily movement produced by skeletal muscles

35
Q

The most variable component of daily EE is…

A

AT

36
Q

AT can vary from an average of ___% of the daily EE up to ____% in extreme conditions during heavy ____ training or competition.

A
  • 30%
  • 80%
  • endurance
37
Q

_____ is extremely important for the maintenance of the daily energy balance.

A

exercise

38
Q

AT can be controlled ______.

A

voluntarily

39
Q

_____ is very high in active individuals, where as _____ is very high in sedentary individuals.

A
  • AT

- RMR

40
Q

However, in contrast to the predictions of the constrained EE model….

A
  • 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
Q

When PA increases via exercise, the non-PA components of EE…..

A

do not decrease as predicted by the constrained model

42
Q

Increments in daily EE shortly after starting an ____ ____ can be greater than the expended energy cost of the exercise.

A

exercise program

43
Q

As training progresses, daily EE does not _____ ____ (despite increasing volume and intensity) –> may be because of improvements in ____ _____ that decrease energy cost of exercise.

A
  • increase linearly

- biomechanical efficiency

44
Q

Diets differing in ____ ____ could result in different responses on energy metabolism.

A

macronutrient distribution

45
Q

Energy balance =

A

body weight maintenance

46
Q

One of the first studies in dietary manipulation took place in _____.

A

1957

47
Q

Weight loss in people with obesity was intimately related to _____ _____ of the diet.

A

macronutrient composition

48
Q

Trends in CHO, FAT, and PRO intake:

A
  • inc. energy CHO + dec. PRO, FAT = inc. obesity

- 1% inc. protein = dec. 32 kcal CHO & dec. 51 kcal FAT

49
Q

Increasing PRO composition of diet may facilitate ____ _____ _____.

A

reducing energy intake

50
Q

Isocaloric diets differing in macronutrient composition may result in …. This over the long term will alter….

A
  • preferential partitioning of energy storage

- the proportions of FM and FFM during weight loss and weight gain

51
Q

Dietary ____, in particular, is known to positively influence ___ during weight loss and weight gain.

A
  • protein

- FFM

52
Q

Energy balance refers to the balance between…

A

EE (RMR, AT, TEF) and energy intake (Kcal, macronutrients)

53
Q

Negative energy balance:

A
  • EE > intake

- weight loss

54
Q

Positive energy balance:

A
  • intake > expenditure

- weight gain

55
Q

RQ:

A
  • respiratory quotient
  • directly measured from tissues (invasive)
  • provides meaningful information with respect to EE and substrate oxidation
56
Q

RQ =

A

VCO2/VO2

57
Q

RER:

A
  • 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
Q

An RQ = 1.00 suggests….

A
  • CHO is being oxidized

- the amount of O2 required for the combustion of glucose equals the amount of CO2 produced

59
Q

An RQ = 0.70 suggests….

A
  • FAT is being oxidized

- fatty acids are a much less oxidized fuel source (fewer O2 molecules)

60
Q

An RQ for _____ is more complicated….

A
  • 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
Q

An RQ of 0.82 suggests…..

A

PRO is being oxidized

62
Q

If a truly accurate RQ is required, a correction has to be made by measuring the amount of ____ ___ _____ over a specific time period.

A

Urinary N excreted

63
Q

For every 1g of N excreted:

A
  • 5.912 L of O2 are consumed

- 4.758 L of CO2 are produced

64
Q

The amount of O2 and CO2 exchanged in the release of energy from ____ can be subtracted from….

A
  • protein

- the total amount of measured gaseous exchange

65
Q

The RQ of an ordinary mixed diet consisting of CHO, PRO, and FAT is usually….

A

0.85

66
Q

In clinical practice, an RER < 0.70 can indicate:

A
  • hypoventilation
  • underfeeding
  • alkalosis
  • ketosis
  • low-carb diet
  • high alcohol diet
67
Q

In clinical practice, an RER > 1.00 can indicate:

A
  • hyperventilation
  • overfeeding
  • acidosis
68
Q

Once RER has been computed from gaseous exchange, the EE is calculated based on….

A

the caloric value of 1L of O2 and 1L of CO2, given various RERs

69
Q

The amounts of ____ and ____ being oxidized in the production of these calories is also possible.

A
  • CHO

- FAT

70
Q

Why is the oxidation of protein ignored in the determination of the non-protein RQ?

A

because under ordinary circumstances the contribution of protein to energy metabolism is so small

71
Q

____ rather than _____ basal or REE has been the practice among clinicians since 1925.

A
  • estimating

- measuring

72
Q

Estimations have been based on:

A
  • body SA
  • body weight
  • calculations from regression equations that incorporate age, sex, weight, height
73
Q

Estimates have been shown to correlate with measurements from ____ _____ and ____ ____ _____.

A
  • indirect calorimetry

- doubly labeled water

74
Q

Commonly used equations to estimate REE in healthy adults:

A
  • Mifflin-St Jeor

- Harris-Benedict

75
Q

Commonly used equation to estimate TEE in healthy, normal weight adults 19 years and older:

A

Dietary Reference Intakes (DRIs)