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Nutrition and Metabolism > Energy Metabolism > Flashcards

Energy Metabolism Flashcards

1
Q

What is the process of glycolysis?

A

The breakdown of glucose to make ATP

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2
Q

What is the function of the TCA cycle?

A

breakdown glucose, protein and fats to make ATP

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3
Q

What is the TCA cycle also known as?

A
  • Kreb’s cycle

- Citric acid cycle

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4
Q

How can you get the product creatine-phosphate?

A

from ATP via creatine phosphokinase

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5
Q

What is creatine-phosphate?

A

phosphate buffer

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6
Q

Which nutrient is the process of beta oxidation for?

A

fats

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7
Q

During daily cycles of feeding and fasting, nutrient breakdown/storage occurs, these are dependent on?

A

hormones

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8
Q

What situations is metabolism which is highly flexible, depending on?

A

feeding and fasting

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9
Q

What is the net effect of metabolism?

A

to produce ATP via oxidative phosphorylation and ETC in mitochondria

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10
Q

How much kcal is 1kJ?

A

0.239kcal

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11
Q

How much kJ is 1 kcal?

A

4.184 kJ

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12
Q

Give examples of areas food energy would cover in humans:

A
  • basal metabolic rate (BMR)
  • the metabolic response to food (TEF)
  • energy cost of physical activities
  • accretion of new tissue during growth/pregnancy
  • production of milk during lactation
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13
Q

What is energy balance?

A

the difference between energy intake (EI) and energy expenditure (EE)

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14
Q

Explain energy equilibrium:

A

zero energy balance, reached when metabolised energy consumption matches the amount of energy spent

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15
Q

What happens when EI > EE?

A

increase in energy gained, usually deposited as fat mass+ some fat free mass (FFM @ muscles)

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16
Q

What happens when EI < EE?

A

decrease in energy stores, a mix of both fat mass and fat free mass

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17
Q

What is a ‘bomb calorimeter’?

A
  • measurement of energy in foods

- measures the total combustible energy of food (theoretical maximum energy)

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18
Q

what is combustible energy also called?

A
  • ingested energy (IE)

- gross energy (GE)

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19
Q

What is the main difference in digestible energy (DE) and metabolisable energy (ME)?

A

DE accounts for some loss as urinary energy (UE)

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20
Q

Given an example of energy loss in incomplete absorption:

A

loss of faecal energy (FE)

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21
Q

Given an example of energy loss in intestinal fermentation:

A

combustible gas

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22
Q

Given an example of energy loss in urinary energy (UE):

A

incomplete protein catabolism

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23
Q

The metabolised energy utilised during metabolic processes is associated with?

A
  • digestion
  • absorption
  • intermediary metabolism of food
  • basal metabolism
  • physical activity
  • growth and lactation
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24
Q

Metabolised energy can be measured and referred to as?

A
  • measured as heat production

- referred to as dietary-induced thermogenesis (DIT) OR thermic effect of food (TEF)

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25
Q

Who developed the Atwater conversion factors?

A

Wilbur Atwarer in late 1890s

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26
Q

What are the Atwater factors?

A
  • carbohydrates
  • proteins
  • fats
  • alcohol
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27
Q

What is the value in kJ/g and kcal/g of the Atwater factor, carbohydrate?

A

17kJ/g, 4kcal/g

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28
Q

What is the value in kJ/g and kcal/g of the Atwater factor, protein?

A

17kJ, 4kcal/g

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29
Q

What is the value in kJ/g and kcal/g of the Atwater factor, fat

A

37kJ/g, 9kcal/g

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30
Q

What is the value in kJ/g and kcal/g of the Atwater factor, alcohol?

A

29kJ/g, 7kcal/g

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31
Q

What contributes to the central/peripheral systems to change eating behavior, appetite and food intake?

A

physiological and environmental factors (e.g. cephalic phase, thought, sight, smell of food, etc)

32
Q

What is the most commonly used method for measuring food intake?

A
  • food recall
  • diet diary

(easy to administer and inexpensive but can misreport)

33
Q

What is daily total energy expenditure (TEE) dependent on?

A
  1. Basal Metabolic rate (BMR) and resting metabolic rate (RMR)
  2. Amount of fat free mass (FFM)
  3. Thermic effect of feeding (TEF)
  4. Physical Activity (PA)
34
Q

BMR accounts for how much % of daily calorie expenditure?

A

60-75%

35
Q

What is the most important determinant of resting metabolic rate?

A

fat free mass (FFM)

36
Q

What are the key determinants of activity energy expenditure?

A
  • genetic traits
  • age
  • sex
  • environmental stimuli
37
Q

What are the key determinants of thermic effect of food?

A
  • diet composition
  • age
  • physical activity
  • obesity
  • insulin resistance
38
Q

What are the key determinants of resting metabolic expenditure?

A
  • fat-free mass
  • fat mass
  • sex
  • age
  • genetic traits
39
Q

What is the global definition of physical activity (PA)?

A

bodiliy movement resulting from contraction of skeletal muscle that results in increase in EE above resting levels

40
Q

What is the global definition of exercise?

A

planned, structured and repetitive movement with the intention of promoting or maintaining one or more component of physical fitness

41
Q

What can 1 MET at rest equates to?

A

3.5mL/O2/kg/min OR

1kcal/kg/h

42
Q

What is gross EE quantified by?

A

O2 consumption and referenced in kcal/min or kJ/min

43
Q

Give the equation for total daily energy expenditure:

A

TEE = REE (resting EE) + TEF (Thermic effect of food) + AEE (Activity EE)

44
Q

What is the method for measuring AEE?

A
  • Doubly labeled water (DLW)
  • Indirect calorimetry
  • heart rate monitoring
  • accelerometry
  • global positioning system
  • pedometry
  • questionaires
  • observation
45
Q

What is usually used to measure TEF and REE?

A

indirect calorimetry

46
Q

What is the one method used to measure across any EE? (gold standard)

A

doubly labelled water (DLW)

47
Q

How does direct calorimetry measure EE?

A

measurement of body’s heat production in calorimeter

48
Q

In using indirect calorimetry, EE is determined by?

A

measuring the amount of oxygen consumed and carbon dioxide produced

49
Q

What the RQ (respiratory quotient) provide information of?

A

metabolic substrate utilization (lipid or carb)

50
Q

How is RQ (respiratory quotient) calculated?

A

dividing the volume of CO2 produced by the volume of O2 consumed

RQ = VCO2/VO2

51
Q

Give two names of portable gas exchange analysers:

A
  • MetaMax3B

- Cosmed K5

52
Q

What is the equation used for indirect calorimetry?

A

Weir equation

53
Q

What is the Weir Equation?

A

REE (kcal/day) = 1.44 (3.94 x VO2 ) + (1.1 x VCO2)

54
Q

Give the RQ value for carbohydrate oxidation:

A

1.0

55
Q

Give the RQ value for lipogenesis:

A

1.0-1.2

56
Q

Give the RQ value for protein oxidation:

A

0.82

57
Q

Give the RQ value for fat oxidation:

A

0.71

58
Q

Give the RQ value for Ethanol oxidation:

A

0.67

59
Q

Give the RQ value for oxidation of mixed diet:

A

0.85

60
Q

What methods are used to measure motion (EE)?

A

accelorometer and pedometers

61
Q

Explain how the doubly labelled water method works:

A
  1. Excretion rate of DLW used to estimate EE
  2. 2 isotopes equilibrate with total body water (TBW)
  3. CO2 production calculated by subtracting 2^H elimination from 18^O elimination

(this method also to measure TBW and hydration)

62
Q

What happens to the levels of deuterium (2^H and 18^O) over the days?

A

decreases (2-3 weeks)

63
Q

Why don’t we always use DLW?

A

very expensive due to the isotope cost

64
Q

What is the role of Arcuate Nucleus (ARC)?

A

in hypothalamus, plays central role in receiving and integrating orexigenic/anorexigenic signals

65
Q

Which region of the brain is not protected by the blood-brain barrier?

A

underlying median eminence region

66
Q

What are the two main ARC (arcuate nucleus) neuronal population which are involved in regulation of food intake?

A
  1. Pro-opiomelanocortin (POMC) neurones

2. Neuropeptide-Y (NPY) and Agouti-related peptide (AgRP)

67
Q

What are POMC neurons for…as well as NPY and AgRP for?

A

appetite-inhibiting producing melanocortins

and co-expressing neurones that are also appetite-inhibiting

68
Q

What do the MC3 and MC4 receptors (melanocortin) do? (they’re inhibited by AgRP and POMC via alpha-MSH)

A
  • increase energy expenditure

- decrease food intake

69
Q

Meanwhile, What does the Y1 and Y5 receptor do? (inhibited by NPY)

A
  • decease energy expenditure

- increase food intake

70
Q

What does the POMC produce?

A

a number of active peptides

71
Q

What does dysregulation of the POMC gene itself OR its expression, lead to?

A

can lead to clinical manifestations such as obesity

72
Q

Appetite regulation takes place of the activity of hypothalamic neural circuits, and they release…?

A
  • neuropeptide signals
  • NPY
  • AgRP
  • melanocortins
73
Q

What may cause EE to adapt in ways not related to changes in metabolic mass?

A
  • changes in mitochondrial dynamics

- hormonal factors such as thyroid and adrenergic function

74
Q

What is thyroid hormones impact on metabolism?

A
  • beta-adrenergic activity (upregulates)
  • mitochondrial function
  • browning of adipose tissues
  • upregulation of gene transcription factors and mitochondrial biogenesis
75
Q

What happens when you stimulate beta-2-receptors in adipose?

A

increases lypolysis (fat breakdown)

76
Q

What are the roles of uncouplers?

A
  1. carry H+ across the inner mitochondrial membrane (NOT through ATP synthase)
  2. Electron transport proceeds but not ATP is formed
  3. Energy dissipated as heat
  4. Biologically useful in maintenance of body temperature in hibernating animals, newborns (adapt to cold)

Nutrition and Metabolism (14 decks)

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