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NUTR*3210 > UNIT 3: ENERGY > Flashcards

UNIT 3: ENERGY Flashcards

1
Q

The sum of all chemical reactions involved in obtaining and utilizing food energy is…

A

Energy metabolism

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2
Q

What does ATP hydrolysis do?

A

ATP hydrolysis releases energy captured in chemical bonds, driving forward metabolic reactions, and physical movement and releasing heat

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3
Q

What do these have in common?

  • physical activity
  • anabolic pathways
  • active transport
  • cell division, growth, reproduction
A

All are work that require ATP

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4
Q

What is a Calorie?

A

Calorie: measure of heat, amnt of energy required to raise 1g water by 1 degC

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5
Q

What is the difference between Calorie and calorie?

A

1 Cal = 1000 cal = 1kcal = 4.18kJ

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6
Q

When a person is in the phases of growth and development, weight gain and obesity, and adults between the age of 20-60… this is what state?

A

Positive energy balance

dietary energy intake > energy expenditure

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7
Q

What are characteristics of a negative energy balance?

A
  • weight loss and infection
  • degrade protein fast to support immune function
  • over the age of 60
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8
Q

The measurement of heat production when food sample is completely combusted in high oxygen environments.

A

Bomb calorimetery

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9
Q

What is heat an indicator of in bomb calorimetry?

A

Amount of energy stored in chemical bonds of foods (C-H)

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10
Q

Maximum amount of energy that can be obtained when food is completely oxidized metabolically or by chemical combustion.

A

Gross Energy

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11
Q

What are the 4 steps to bomb calorimetry?

A
  • dry and weigh sample
  • prepare bomb (high O2)
  • ignite sample
  • measure energy (heat released, absorbed by water, change in temp)
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12
Q

What is a major limitation of gross energy?

A
  • measures max amount of energy liberated, therefore…
  • does not take into account of energy for physiological work (digestion and absorption)
  • human body does not digest and absorb all food energy
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13
Q

What is digestible energy?

A

Gross energy - energy lost in feces

  • energy lost in feces can be determined with % digestibility
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14
Q

Energy is lost from gases and urine (urea - protein). After accounting for this loss, what is this called?

A

Metabolizable energy.

ME = DE - energy lost in urine/gas

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15
Q

What do Atwater’s Physiological Fuel Values measure?

A

Metabolizable Energy
(gross energy - feces - gases - urine)
units: kcal/g

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16
Q

What is the ratio for Atwater’s Physiological Fuel Values?

A

ME (kcal/g)
Fat: 9
Protein: 4
Carb: 4

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17
Q

In fatty acids…

lower GE occurs due to:

A
  • percent of oxidized carbons represents large amount of molecule
  • increasing number of double bonds (partially oxidized)
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18
Q

Calories in nutrition fact labels represent ____ energy.

A

Metabolizable energy

- from Atwater’s Physiological Values

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19
Q

How do you calculate total calories?

A

Fat x 9kcal/g
Carb x 4kcal/g
Protein x 4kcal/g

20
Q

Define HIF.

A

HIF - heat increment of feeding: obligatory energy expenditure for process (energy expenditure while obtaining energy from food)
i.e. chewing, gut secretion, motility, active transport…

21
Q

How is net energy determined?

A

Metabolizable Energy (ME) - Heat Increment of Feeding (HIF) = Net Energy (NE)

22
Q

HIF will be larger for ____ sized meals.

HIF will be larger for ___ macromolecules compared to ____ and ____.

A

Larger expenditure for larger meals
larger for proteins (15%)
than carbs (10%)
than fats (5%)

23
Q

Components of energy expenditure include:

A
  • HIF (10%)
  • BMR (60% energy expenditure)
  • Physical activity (30%)
  • Thermoregulation (10%)
24
Q

What is BMR?

A

basal metabolic rate

  • the measure of energy spent…
  • shortly after waking
  • post-absorptive state/fasting (avoid HIF expenditure)
  • lying down and relaxed - not asleep
  • room that is comfortable temperature so there is no energy spent in thermoregulation
25
Q

Is BMR constant?

A
  • No, it can drop during periods of malnutrition or starvation.
  • you can survive on intakes below BMR but tend to be in negative energy balance
26
Q

What part of the body regulates BMR?

A

hypothalamus/pituitary/thyroid hormone signalling axis

27
Q

How do you estimate BMR across species?

A

Kleiber’s Law

28
Q

What is Kleiber’s Law?

A
  • metabolic rate varies with body weight by 0.75 exponent
Metabolic Rate (is proportional to) Mass^0.75
- note* this is not applicable to humans
29
Q

A ____ surface area to body weight ratio would conserve energy and lower energy expenditure.

A

lower

i.e. elephant

30
Q

What are the equations used to calculate BMR for humans called?

A

Harris-Benedict Equations

31
Q

Metabolic rate is ____ variable in women than men

A

Less variable

  • higher constant in female (665)
  • male constant (66)
32
Q

What are 5 factors that affect BMR?

A
  • genetics
  • age
  • gender
  • higher exercise/physical activity
  • temperature
33
Q

Age: ____ people have higher BMR

A

young people

because greater % lean mass

34
Q

Gender: ____ people have higher BMR

A

men

because greater % lean mass

35
Q

Temperature ____ increase BMR

A

higher thermoregulation

*note thermoregulation cannot occur during BMR measurement

36
Q

Bomb calorimetry is direct or indirect calorimetry

A

Direct calorimetry

- assess potential energy

37
Q

How is energy expenditure measured?

A

indirect or direct calorimetry

38
Q

Humans and animals are used for what type of calorimetry?

A

Direct calorimetry

39
Q

How is energy measured in direct calorimetry?

A
  • emitted heat absorbed by water/walls (measure change in heat) = sensible heat
  • account of sweat and vapour in expired air (measure change in water vapour) = insensible heat loss
40
Q

What is the main difference between what indirect vs direct calorimetry measures?

A

Indirect: O2 and CO2

Direct: H2O and heat

41
Q

What is the purpose of measuring O2 and CO2 in indirect calorimetry?

A

to indirectly measure the H2O and heat produced from combustion

42
Q

What needs to be estimated in order to accurately estimate energy expenditure in indirect calorimetry?

A
  • what fuels are being utilized!
43
Q

What sample is needed in order to calculate protein oxidized in indirect calorimetry?

A
  • urine sample to calculate urinary nitrogen

- this quantifies oxidized protein

44
Q

What is RQ?

A

Respiratory Quotient

- volumes of oxygen consumed and volumes of carbon dioxide measured from indirect calorimetry

45
Q

Formula for RQ

A

RQ = (CO2 produced (L)) / (O2 consumed (L))

46
Q

Match the RQ values to their macromolecules:

0.7, 0.82, 1.0

A

Carbs 1.0
Protein 0.82
Fat 0.7

  • in calorimetry experiments protein loss is uncommon, but if protein is lost (loss of lean body mass) then urinary nitrogen would need to be measured
47
Q

Given volume of O2 consumed and CO2 produced, how do you find calories produced.

A
  • find RQ (CO2produced / O2consumed)
  • find caloric equivalent
  • multiply caloric equivalent by L produced or consumed
  • this gives you calories produced per time of measurement

NUTR*3210 (15 decks)

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