121 - Regulation of Energy Systems Flashcards

1
Q
Components of daily energy expenditure
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A

1) Sleeping metabolic rate + Arousal
2) Basal metabolic rate (when awake)
3) Thermic effect of food (heat released when food is digested)
4) Activity (variable amount of energy expenditure)

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2
Q
Measurements of energy expenditure
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A

1) Doubly-labelled water
2) O2 consumption
3) Heart rate-based estimation of VO2
4) Activity monitors
5) Population-based algorithms

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3
Q

Doubly-labelled water

A

Label H and O in water, look at how quickly it is metabolised.
Very accurate, but difficult to do.

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4
Q

How can VO2 be estimated with measuring heart rate?

A

Linear relationship between the two.

Can be inaccurate, as factors other than VO2 can alter heart rate.

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5
Q
Determinants of energy expenditure 
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A

1) Adrenaline, thyroid hormones
2) Muscle mass and oxidative capacity
3) Exercise/physical activity levels
4) Non-exercise activity thermogenesis
5) Shivering thermogenesis

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6
Q

Effect of oxidative capacity on basal metabolism

A

More oxidative fibres in muscle (slow-twitch) associated with lower body mass. Might metabolise fat more effectively.

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7
Q

Non-exercise activity thermogenesis

A

Fidgeting, tapping, etc during day can expend energy.

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8
Q

Brown fat

A

Similar metabolic profile to muscle.
Present in low amounts in adults.
Uptakes glucose particularly in cold conditions.

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9
Q

Uncoupling protein

A

Uncouples e- transport chain with mitochondrial ATPase, making the process much more inefficient. Need to expend more energy to make the same amount of ATP, generating a lot of heat in the process.
Brown fat has high transcription levels of uncoupling protein, used by hibernating animals.

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10
Q

50% of current anti-obesity drugs target what?

A

CNS

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11
Q

Examples of hormones that inhibit hunger (short-term)

A

CCK, GLP-1, PYY (short-term)

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12
Q

Examples of hormones that inhibit hunger (long-term)

A

Leptin

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13
Q

Leptin and regulation of body mass

A

Released by adipose tissue.

As adiposity increases, leptin levels increase, which reduces drive to eat.

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14
Q

Effect of genetic leptin deficiency

A

Increase in adiposity.

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15
Q

Why can’t obesity be treated with leptin?

A

Leptin insensitivity arises

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16
Q

Example of biological factors affecting body weight

A

If monozygotic twins overfed, increase in weight fairly uniformly

17
Q

Example of an inhibitor of fat absorption

A

Xenical

18
Q

Side-effect of Xenical

A

Steatorrhoea

19
Q

Effectiveness of low-carb diet

A

Found to be mildly effective, but more data needed

20
Q
Things associated with successful weight loss
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A

1) Low calorie, low-fat diet with minimal variation
2) Eating breakfast every day
3) Frequent self monitoring
4) Regular exercise ~1 hr/day
5) Limiting TV viewing