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Nutrition > Energy > Flashcards

Energy Flashcards

1
Q

6Co2 + 6O2 =

A

C6H12O6 + O2
Photosynthsis
686 kcal/ mol [endergonic/ energy required]

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2
Q

C6H12O6 + O2 =

A

6Co2 + 6O2
Oxidation
-686 kcal/ mol [exergonic/ erergy released]

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3
Q

Flow of energy through biosphere

A 
Sun [ Solar energy]
Plant [ Photpsynthesis]
[Chemical energy]
Animal [chemical energy released in catabolism]
[Heat loss/ --> Work]
Mechanical Work/ Chemical synthesis -->
Transport across membrane
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4
Q

Joule

A

S.I unit

Energy expended when 1 kg is moved 1 m by a force of 1 Newton

1 MJ= 10^3 kJ

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5
Q

Kilo - calories (kcal)

A

The amount of heat required to raise the temperature of 1 L water from 15C to 16C

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6
Q

Bomb Calorimeter

A

An electrical heating device starts the reaction inside a sealed reaction vessel.

The temperature rise of the water which surrounds it is measured.

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7
Q

Energy of marconutrient

A 
Lipid = 9 kcal/g
CHO = 4 kcal/ g/
Protein = 4kcal/ g
Alcohol = 7 kcal/ g
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8
Q

Sources of energy in the British diet

A

47% CHO
30% Fat
15% Protein
8% Alcohol

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9
Q

Calories source ~ 1965 & 1995

[Developing country]

A

Developing Countries
Less cereals, pulse, roots & tubers,
More meat, fruit & veg, oil crops, ,fish & seafood, dairy & eggs
More calories intake

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10
Q

Calories source ~ 1965 & 1995

[Developed country]

A

Developed Countries
Less cereals, pulse, roots & tubers,
More oil crops, ,fish & seafood, dairy & eggs
meat, fruit & veg relative the same
More calories intake

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11
Q

Calories source ~ 1965 & 1995

[World]

A

More oil crops
Less pulse
Others relative the same
More calories intake

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12
Q

Calories source ~ Female & Male

A

Female has a few more % of CHO (cereals/ potatoes/ savory snack), dairy, veg, fish
Less meat, sugar, drinks (inc alcohol) than male

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13
Q

Energy density of food

A

Weight of food per 1000 kcal

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14
Q

Energy density change

A

Prehistoric/Subsistence diet = low energy density

Modern/western diet = high energy density

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15
Q

Indirect Calorimetry

A

Estimates heat production by determing O2 consumption or CO2 production

Provides a means of estimating the composition of oxidized fuels

carried out on an individual basis, which makes this a fairly time-consuming process ideal for smaller studies

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16
Q

Indirect calorimetry in closed circuit

A

Analyzer (i.e. animals) in respiration chamber (closed environment)

Measure O2 consumption or CO2 production over time?

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17
Q

Indirect calorimetry in open circuit

A

measurement of oxygen consumption (VO2) to assess the metabolic intensity of the exercise.

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18
Q

Indirect Gas Analysis Calorimetry

Fundamental Principles

A
  • the volume of oxygen consumed (VO2) by the body is
    equal to the difference between the volumes of inspired and expired oxygen.
  • the volume of carbon dioxide produced ( VCO2) by the body is equal to the difference between the volumes of expired and inspired carbon dioxide
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19
Q

Limitation of Indirect calorimetry

A

Measuring the whole body - the sum of all active tissue in body, not just contracting skeletal muscle.

Needs sophisticated and expensive equipment.

Highly sensitive to measurement error.
.
Can only be accurately used for metabolic intensities, economy, efficiency, and energy expenditure during steady state exercise

Requires subjects to wear apparatus on face or in
mouth

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20
Q

Energy cconomy & efficiency

A

Economy - refers to the energy cost of an exercise condition.

Efficiency -the mechanical energy produced relative to the metabolic energy expenditure

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21
Q

Doubly Labelled Water

A

The DLW method uses the natural occurring stable isotopes of water (D2O and H218O) to assess energy expenditure, body composition and water flux in humans

[Hydrogen replaced with deuterium
16Oxygen replaced with 18O]

Measure:
18O in CO2 exhaled
Deuterium in excreted water

As 18O is lost from the body in the form of water and carbon dioxide (CO2), whereas deuterium is lost only as water, the difference in loss from the body reflects the CO2 production during the period.
[CO2 production is the result of fat, carbohydrate and protein oxidation/ an index of energy expenditure.]

used samples of urine, blood or saliva for analysis
(urine is most commonly used)

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22
Q

Estimated average requirement (EAR) for Male & Female

A

M 75kg 19-59 yrs = 2553kcal
F 60kg 19-50 yrs = 1940 kcal
F 63kg 51-59 yrs = 1912 kcal

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23
Q

Estimated average requirement (EAR) for children and adolescents

A

0 - 3 months F= 515 M= 545
10- 12 months F= 865 M= 920
7- 10 yrs F= 1740 M= 1970
15- 18 yrs F= 2110 M= 2755

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24
Q

Average daily total energy intake and percentage of EAR – UK (2003)

A 
M = 92% of EAR
F  = 85% of EAR
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25
Q

Energy usage

A

Metabolism and homeostasis

  • Thermogenesis
  • Tissue turnover
  • Biochemical reactions
  • Basal metabolic rate (75 % of energy usage)

Work
(25 % of energy expenditure)

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26
Q

BMR

When is it measured?

Compare between F/ M

Children / Adults
Rate of BMR change vs age

Adults/ Elderly

How many % of energy requirement

A

Basal metabolic rate

Energy expenditure in the post-absorptive state, under standardised conditions of thermal neutrality, awake but completely at rest.

BMR is measured when a person is at complete rest

Infants and young children have a proportionately high BMR for their size due to their rapid growth and development. After 20 years, it drops about 2 per cent, per decade.

Men usually have a higher BMR than women since they tend to have more muscle.

Older adults usually have a lower BMR than the young since the amount of muscle tends to decrease with age.

The BMR accounts on average for about three quarters of an individual’s energy needs.

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27
Q

PAR

A

Physical activity ratio

Energy cost of physical activities, as a ratio of BMR (per minute)

28
Q

PAL

A

Physical activity level

Sum of PAR x time spent for each activity over 24h, as a ratio of BMR (per 24 hours)

29
Q

Factors that affect BMR

A

Age: higher in young. Less “lean body mass” (LBM) in old.

Height: greater BMR for tall, thin people.

Growth: greater BMR in children and during pregnancy

Body composition: greater BMR with more LBM.

Fever/stress: increase BMR

Temp. of environment: both extreme cold and heat increase BMR

Fasting/starvation: lowers BMR

Thyroxin: key factor in BMR regulation

30
Q

Metric BMR Formula

A

Women: BMR = 655 + ( 9.6 x weight in kilos ) + ( 1.8 x height in cm ) - ( 4.7 x age in years )

Men: BMR = 66 + ( 13.7 x weight in kilos ) + ( 5 x height in cm ) - ( 6.8 x age in years )

31
Q

Classification of occupational work by PAR

A

Light work: PAR = 1.7
professional, clerical workers, administrative staff

Moderate work: PAR = 2.2 (men) 1.7 (women)
students, sales staff, domestic service

Moderate-Heavy work: PAR = 3.0(men) 2.3 (women)
machine operators, labourers with machines

Heavy work: PAR = 3.8(men) 2.8(women)
labourers without machines, bricklaying, agricultural workers

32
Q

Total Energy Expenditure

A

TEE = BMR x PAL

33
Q

Main catabolic processes

A
  • Break down of macromolecules to TCA cycle precursors –> TCA cycle– the central pathway to catabolism
  • Release of electrons for the electron transport chain
    & Production of ATP in the electron transport chain
34
Q

Phosphorylation

A

ADP –> ATP

Substrate-level phosphorylation = Transferring a phosphate directly to ADP from another molecule

Oxidative phosphorylation = Use of ATP synthase and energy derived from a proton (H+) gradient to make ATP

35
Q

Glycolysis

A

Substrate-level phosphorylation

Break down of 1 glucose molecule into 2 pyruvate molecules

36
Q

Citric Acid cycle/ TCA cycle

A

Substrate-level phosphorylation

1 x pyruvate + 1 x NAD+ –> 1 x acetyl CoA + 1 x CO2 + 1 x NADH

1 x acetyl CoA –> 1 x CoA + 1 x citric acid (6C)

1 x citric acid + 2 x NAD+ --> 2 x CO2 + 2 x NADH
1 x (4C) + 1 x ADP + Pi --> 1 x ATP
1 x (4C)  + 1 x FAD --> 1 x FADH2
1 x (4C) + 1 x NAD+ --> 1 x NADH + 1 x Oxaloacetate (4C) --> +  1 x acetyl = 1 x citric acid (6C)
37
Q

Chemiosmosis

A

Electron transport chain & oxidative phosphorylation at inner mitochondrial membrane

38
Q

Catabolism -> Macronutritient to energy

A

Bulk food is digested in the mouth, stomach and small intestine to yield small molecules

Sugar/ fatty acid/ amino acids are degraded in the cytoplasm to yield acetyl- CoA

Acetyl CoA is oxidized inside mitochondria by citric acid cycle to yield CO2 and reduced coenzymes

The energy transferred to the reduced coenzymes in stage 3 is used to make ATP by the coupled pathways of electron transport and oxidative phosphorylation.

39
Q

Lipid metabolism

A

Break down to glycerols and fatty acid

–> Fatty acid oxidation–> Acetyl CoA

40
Q

CHO metabolism

A

Break down to glucose and other sugars

–>Glycolysis [ ATP & pyruvate] –> Acetyl CoA

41
Q

Protein metabolism

A

Break down to amino acids

–> Amino acid catbolism [ pyruvate] or straight into Acetyl CoA/ Citric acid cycle

42
Q

Metabolism in liver

A

Glycolysis– > pyruvate [outside liver]
–> Acetyl CoA [synthesis fatty acid] –> Citric acid cycle

The Cori Cycle [ Liver muscle]

43
Q

The Cori Cycle

A

[In Liver] 2 x Lactate –> 2x pyruvate–> 1 x glucose (6 ATP required)
[Transfer to muscle by red blood cells]

[ In muscle ]
1 x glucose –> 2 x ATP & 2 x pyruvate –> 2 x Lactate
[Transfer to Liver]

44
Q

Metabolism in brain

% of basal metabolic rate

A

Glycolysis– > pyruvate –> Acetyl CoA [synthesis ketone bodies] –> Citric acid cycle

  • 20 % of basal metabolic rate
  • Absolute requirement for glucose
  • Will adapt to ketone bodies in starvation
45
Q

Metabolism in muscle [aerobic]

A

Glycolysis– > pyruvate [outside liver]

–> Acetyl CoA [synthesis fatty acid] –> Citric acid cycle

46
Q

Metabolism in muscle [anaerobic]

A

1 x glucose –> 2 x ATP & 2 x pyruvate –> 2 x Lactate

–> The Cori Cycle

47
Q

Catabolic reaction

A

Glycogen –> glucose & ATP & H2O & CO2

Triglyceride –> [glycerol & ATP] & [Fatty acids & ATP] & H2O & CO2

Protein –> Amino acids & ATP & H2O & CO2 & Urea

48
Q

Anabolic reaction

A

2 x glucose & ATP –> glycogen

1 x Glycerol & 3x Fatty acids & ATP –> Triglyceride

2 x amino acids & ATP –> protein

49
Q

Conversion of sugars to fats

A

Pyruvate –> acetyl CoA –> Fatty acyl CoA –> Triglycerides –> Fatty acid –> Fatty acyl CoA –> acetyl CoA

Fatty acid [+ Insulin / - Epenepherine] –> Fat
Fat [ - Insulin/ + Epenepherine] –> Fatty acid

50
Q

Metabolism of Fructose in the liver

A

Fructose metabolism bypasses conversion of glucose to glycerol (storing the energy) and the regulatory activity of phosphofructokinase, lots of acetyl coA produced for fatty acid synthesis

Fructose does not stimulate the secretion of insulin or leptin and does not suppress ghrelin as effectively as glucose or galactose, less satiating (full satisfying)

51
Q

Control of energy balance

A

Increasing BMI= increased BMR & increased physical activity energy expenditure

52
Q

Appestat theory

A

Hunger Satiety signals energy expenditure

Satiety signals

  • Feeding status
  • Energy stores
53
Q

Hunger and appetite

A
  • Gut fill cues, and nutrient sensing in the liver allow neural signalling via the vagal nerve direct to the brainstem, which can then stimulate other components of the brain including the hypothalamus
  • Amygada learned behaviours
  • Hypothalamus, both satiety and hunger centres influenced by neural stimulation, nutrient sensing, (glucose) insulin and glucagon and hormones
54
Q

Ghrelin

A

Ghrelin produced by ghrelin cells (in GI/ stomach) when stomach is empty, signal vagal nerves & hypothalamus to increase hunger, gastric acid secretion and gastrointestinal motility to prepare for the increase food intake.

The hormone also regulatw the distribution and rate of use of energy

55
Q

Leptin

A

Leptin is a hormone made by adipose cells. It acts on vagal nerves & hypothalamus to inhibite hunger, helps to regulate energy balance.

56
Q

Leptin in appetite control

Low/ high level?

A

Low levels =
Increase appetite
Reduce fecundity

High levels =
Suppress appetite
Increase uncoupling protein expression
Increase lipase activity

57
Q

Gut fill cues

A

Cholecystokinin (CCK) in Duodenum

  • Glucagon like peptide (GLP1)
  • Oxyntomodulin
  • Peptide YY
    [all 3 in Gut endocrine cells]
58
Q

Prevalence of Adult obesity in EU

A

BMI > 30

F 25- 30% in eastern EU
20 - 25% in UK, Germany, Turkey

M 20 - 25% in UK, Finland
15- 20% in Germany
0 -10% in Eastern EU, Turkey

59
Q

Consequence of increasing BMI

A

Men have BMI over 30 has greater relative risk of death than women with BMI over 30

60
Q

Health risks of obesity

A

Cancer

Cardiovascular disease

  • Coronary heart disease
  • Stroke
  • Hypertension

Respiratory disease

Type 2 diabetes

Metabolic syndrome

Osteoarthritis

61
Q

Most prevalent cause of the metabolic syndrome

A

Intra-abdominal (visceral) obesity

62
Q

Visceral adipose tissue in obesity

A

Hypoxic (don’t get enough oxygen)

  • Glycolytic - Lactate producing
  • Necrosis
  • Macrophage infiltration
  • Chronic inflammation - Inflammatory cytokines / Oxidative stress/ Cortisol

Lipolytic tissue
- Releases NEFAs- Inhibit glucose/ Inhibit the insulin receptor

Suppressed adiponectin release - Stimulates insulin effect

63
Q

Insulin

A

A peptide hormone produced by beta cells in the pancreas.

Regulates the metabolism of CHO and fats:

  • by promoting the absorption of glucose from the blood to muscles and fat tissue
  • by causing fat to be stored rather than used for energy.

Inhibits the production of glucose by the liver

64
Q

Metabolic syndrome - cluster of disorders linked with Obesity

A

See energy slide 79

65
Q

Normal body store

A 
Fats = 141000 cal
Protein = 24000 cal
CHO = 300 cal

for 80 days fuel store until fatel

66
Q

World hunger 1998 -2000

A

> 35 % population in Africa and Asia
20- 35% in India and N. Africa, S. America
5- 20% in S. America, Russia, China, E. Asia

Nutrition (22 decks)

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