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NUTR*3210 > Unit 3 Notes > Flashcards

Unit 3 Notes Flashcards

1
Q

What is energy balance?

A

The sum of energy intake and energy expenditure

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2
Q

What is energy metabolism?

A

All the chemical reactions involved in utilizing and obtaining food energy.

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3
Q

What is energy?

A

The capacity to do metabolic or physical work

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4
Q

What is the predominant source of cellular energy and how is it obtained?

A

ATP is the cellular source of energy which is obtained through the consumption of macronutrients.

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5
Q

What is energy measured in as?

A

Calories/calories

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6
Q

What happens to all macronutrients after being broken down?

A

After being broken down into units the macronutrients will be oxidized into carbon dioxide and a small amount will be used to create ATP (food energy used to do physical or metabolic work).

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7
Q

The macronutrients protein is broken down and used for what?

A

The macronutrients proteins are broken down into amino acids which can be used by the body to make enzymes (which are proteins) and the body can make its own proteins.

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8
Q

What is the macronutrients fats broken down by the body to make?

A

Dietary fats are broken down to make cholesterol, storage triglycerides and membranes

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9
Q

What is the macronutrients carbohydrates broken down by the body to make?

A

The macronutrients carbohydrates when broken down is used to make glycogen, glycoproteins and glycolipids.

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10
Q

What will the hydrolysis of ATP do?

A

The bonds within ATP molecules have energy. When there is a hydrolysis reaction it will attack the bonds of the ATP molecules. This will release the energy within these bonds which will drive metabolic reactions and physical movements

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11
Q

What are a few physical and metabolic examples of when ATP will be needed?

A
  1. Physical energy (running outside)
  2. Active transport (seen in the membrane bilayer of the microvilli to maintain sodium (Na+) levels higher in the lumen than inside the body
  3. For growth, cell division and reproduction
  4. anabolic pathway (small molecules being built into larger molecules)
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12
Q

What is a calorie?

A

A calorie is a measure of heat and looks at how much energy is required to raise the temperature of water by 1 degree. (The hydrolysis of ATP releases energy from the breaking of the bonds).

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13
Q

What is the difference between calorie and Calorie?

A

calorie is looking at how much heat is required to raise 1 gram of water by 1 degree, these are small calories. Whereas, Calories is looking at 1000 calories or 1 kcalories and looks at how much energy is required to raise the temperature of 1L of water by 1 degrees

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14
Q

1 kcal = _____ kj

A

1 kcal = 4.18 kj

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15
Q

The energy captured in the bonds of carbohydrates, fats and proteins is typically released as?

A

Heat.

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16
Q

What does the calorie portion on nutrition labels refer to metabolized energy or gross energy?

A

Metabolized energy as some of the energy found in food is not actually able to be obtained in our bodies.

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17
Q

Does muscle contain more energy and less water or less energy and more water.

A

Muscle does not contain as much energy and contains more water. Whereas, fat contains more energy and less water. This is why after a workout when muscle may develop and fat is lost one is losing energy but weight doesn’t change as more water is stored in the muscle maintaining the weight difference despite the negative energy balance.

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18
Q

What is the difference between positive energy balance and negative energy balance?

A

Positive energy balance is when you are consuming more energy than being expanded which is needed for growth but can cause weight gain and obesity.

Negative energy balance is when you are consuming less energy than being expanded. This can cause weight loss and an increase in infection rate. When you have a fever the body will degraded proteins faster to try to support immune function which can lead to weight loss as well.

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19
Q

What can occur from having a positive energy balance over a period of time?

A

Weight gain, obesity, cardiovascular diseases, insulin resistance (desensitized insulin receptors) and infertility.

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20
Q

What can occur from having a negative energy balance over a period of time?

A

Weight loss, increase in infections and fevers

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21
Q

Why do we not think of energy balance or requirements as RDA and UL?

A

This is because the amount of energy one requires based on their physical activity and basal metabolism varies and if the same amount was recommended like it is for micronutrients at individuals of the same age and life stage could cause one to exceed the UL and some to go below the RDA based on their basal metabolism and energy expenditure which can cause health problems.

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22
Q

Besides energy intake and outtake what else is energy balance based upon?

A

Energy balance is also based upon the brain and someones desire for food intake and ability to feel satisfied after consuming a meal.

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23
Q

Think back the rat study of the different colonic microbes in rats, lean and obese. Did this contribute to the mouses weight? Explain what this can indicate?

A

When rats where give obese colonic microbes they became obese and when rats where given lean microbes they remained more lean. This means that some individuals could already be exposed to being overweigh or not.

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24
Q

Explain obesogenic environment.

A

This is when the environment and conditions one is in could lead to obesity. This can be maybe not having enough money to buy healthy foods and one can lean to cheaper more unhealthier options. Likewise, if eating out is a more common thing in a house hold this could also contribute to weight gain as well.

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25
Q

What is the prevalence for obesity? Have we seen an increase or decrease in the prevalence for obesity?

A

This is the amount of individuals in an area who are obese. We have seen an increase in the prevalence for obesity.

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26
Q

What are the essential roles macronutrients perform in the body?

A

building cells and tissues and perform work.

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27
Q

What does the body do to the molecules of macronutrients?

A

The body will extract the macronutrient molecules from food and oxidize them via glycolysis and the citric acid cycle. This oxidation releases energy from the bonds of the ATP which can be used for metabolic reactions and physical movements.

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28
Q

What two ways are food molecules extracted to produce metabolic energy (energy from the food which can do physical or metabolic work)?

A

Molecules from food can be extracted through the citric acid cycle and glycolysis producing metabolic energy

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29
Q

How does the body store energy from the macronutrients?

A

The body will store energy from the macronutrients as ATP.

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30
Q

What is the fate of ATP in the body?

A

The ATP will be hydrolyzed which goes and attacks the bonds releasing the energy stored within them for metabolic reactions and physical work and is released as heat which spread out and be released form the body.

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31
Q

What is the ultimate product of metabolism?

A

Heat. Energy is heat and is the amount of energy required to raise the temperature by 1 degree so energy released is heat and metabolic work and physical activity requires the use of energy.

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32
Q

What are the three byproducts produced when we oxidize food?

A
  1. Water
  2. Carbon dioxide
  3. Heat
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33
Q

For an oxidation reaction does it need oxygen?

A

Yes it needs oxygen which is why we breathe in oxygen and release carbon dioxide. The oxygen is needed to oxidize the molecules to produce carbon dioxide and ATP.

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34
Q

How much energy is released as heat during an oxidation reaction and how much is stored as ATP which releases energy through a hydrolysis reaction.

A

60% is released as heat during oxidation

40% is stored as ATP

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35
Q

Is the total amount of heat is released combustion and cellular respiration the same? How?

A

Yes, the total amount of heat released through cellular respiration and combustion is the same. In combustion outside of the body the substrate is burned in a high oxygen environment (our atmosphere) and when burned carbon dioxide, water and heat are released. Whereas, in cellular respiration (combustion inside the body) around 60% of the energy is released as heat and 40% is temporary captured as ATP inside the body. This ATP will be used during metabolic reactions and physical activity will be used so ultimately 100% of the energy produced in the body through cellular respiration will be released as heat like combustion outside the body.

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36
Q

How is the ATP used in metabolic processes?

A

ATP is used in metabolic processes in heat releasing processes.

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37
Q

What is gross energy?

A

Gross energy is all the energy that is released during complete combustion with oxygen. The maximum amount of energy which can be released from the food .

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38
Q

Do all macronutrients contain the same amount of energy?

A

No not all macronutrients contain the same amount of energy and as a result researchers use bomb calorimetry to determine the amount of energy that is found in food.

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39
Q

Where is energy stored a lot in?

A

The hydrogen and carbon bonds in food.

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40
Q

What is heat an indicator of?

A

Heat is an indicator of the amount of energy which is stored within the bonds of food as when these bonds are broken they release energy as heat. (calories which is the energy is looking how much energy is required to raise the temperature 1 degree

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41
Q

What is the difference between combustion and oxidation?

A

Combustion requires you to burn something to get it to react with oxygen and oxidation does not require one to burn something to get it to react with oxygen. In the body we oxidize and outside we need to use combustion.

42
Q

How can water vapour and heat produced be measured in the human body?

A

To measure the amount of heat and water vapour produced by a food researchers can measure the amount of oxygen taken in and the amount of carbon dioxide released to indirectly measure the amount of oxygen.

43
Q

How does a bomb calorimetry work?

What does bomb calorimetry determine?

A

The food will be completely burned in a container in a high oxygen environment. The heat released through the breaking of the bonds (especially C-H bonds) will cause an increase in temperature. The water value is measured before so it can indicate exactly how many degrees the water increased.

Bomb calorimetry determines the gross energy which is the maximum amount of energy which can be generated from the breaking of the bonds.

44
Q

Explain the steps for bomb calorimetry.

A
  1. dry the sample of food and weigh it. Place the sample inside a enclosed chamber, known as the bomb.
  2. The bomb will be filled with a high amount of oxygen via oxygen valves. There is a wire, one end of the wire is touching the food and the other end is outside the chamber and is used to ignite the food.
  3. The chamber which surrounds the bomb is filled with water. The food-oxygen bomb is ignited.
  4. The heat that is released through the breaking of the bonds will be absorbed by the water, with this absorption causing the water temperature to rise.

Note the chamber is completely sealed from the outside environment to prevent an increase in temperature not being directly related to the amount of energy released from the food.

45
Q

Does the bomb calorimetry give the metabolized energy? Why or why not.

A

No the bomb calorimetry does not give the metabolized energy as it gives the maximum amount of energy which can be produced by the food through the breaking of the bonds in macronutrients. However, our bodies are not able to achieve the maximum amount of bond breaking to get that level.

Likewise, the bomb calorimetry does not consider the amount of energy lost through physiological work like digestion and absorption.

46
Q

List the 3 main limitations to the bomb calorimetry method.

A
  1. not all food is fully digested and absorbed. This means that not all energy is released and absorbed. An example is fibre, not all the energy in fibre is fully extracted thus GE - energy in feces = the digestible energy of fibre.
  2. The energy loss through gas and urine after consuming macronutrients (mainly proteins in the form of urea). This needs to be removed from the gross energy to determine the total digestible energy.
  3. Digestible energy - energy lost in urine (and gas but gas is normal ignored) = metabolized energy.
47
Q

What is the equation for metabolized energy?

A

Metabolized energy = digestible energy - energy lost in urine.

48
Q

Explain how to get the metabolized energy?

A
  1. gross energy - energy lost in feces (not digested and absorbed) = digestible energy
  2. Digestible energy - energy lost in urine (gas) = Metabolized energy
49
Q

What did metabolizable energy come from?

A

Wilbur Atwater idea of physiological fuel values

50
Q

Rank the macronutrients from greatest digestibility to lowest.

A

carbohydrates (97%), fats (95%) then proteins (92%).

51
Q

How did Atwater determine the digestible energy (DE)

A

Atwater took the gross energy of the food determine by the bomb calorimetry and multiplied it by it’s percent (i.e. carbohydrates multiple by 0.97) this gave the digestible energy

52
Q

What is the main energy containing compound in urine?

A

The main energy that is lost in the urine which needs to be removed from the gross energy is urea which is produced from protein. The urea is the main way the body excrete nitrogen.

53
Q

How does the body excrete nitrogen?

A

The body excrete nitrogen from the urine in the form of urea.

54
Q

How much energy is lost in the urine?

A

around 1.25 kcal, this is why the digestible energy needs to have the energy lost in the urine subtracted to determine the true amount of energy that is being metabolized by the body.

55
Q

What is an example of when we would need to subtract values other then urea from the urine?

A

a poorly controlled diabetic who has a high level of glucose in the body can start to have glucose in the urine being released. This means that the metabolized energy for carbs would be less then 4.

56
Q

What are the Atwater physiological fuel values we use to determine the amount of metabolized energy? (like carbs, fats and proteins)

A

carbs is 4, protein is 4 (went from 5.25 to 4 because of the 1.25 kcal lost in the urine as urea) and fats are 9.

57
Q

Why do fats provide such a large amount of energy?

A

Fats are composed of a high amount of H-C bonds, which provide a predominant amount of energy through the breaking of these bonds.

58
Q

True or false. Alcohol provides 50% more energy then gasoline.

A

False, gasoline is saturated with H-C bonds and if you had 50% of gasoline oxidized you would have the amount of energy produced through the oxidation of alcohol.

59
Q

Does methanol burn and release energy more controllably than methane.

A

Yes, however the partial oxidation of methane will produce methanol which releases heat in a much more controlled way.

60
Q

What does metabolic oxygen or oxygen from the environment react with in food?

A

The metabolic oxygen or the oxygen from the environment reacts with the carbon in food. This reaction with carbon in food causes the release of energy from the bonds H-C bonds and other bonds. In the body 60% of this energy is released as heat and 40% is stored as ATP in the body and will be used to do work (metabolic or physical)

61
Q

Why do fats have more potential for remain oxidation than proteins and carbohydrates.

A

They have lower inherent oxidation. This means because they have less oxygen atoms per carbon than proteins or carbohydrates they have more bonds which can be broken and release energy. As proteins and carbohydrates have more oxygen molecules in their structures which are already oxidized. Carboxylic group make the molecules oxidized and unable to really obtain any additional energy.

62
Q

What is the structure of the fatty acid stearic?

A

The stearic acid is 17 carbons long saturated with hydrogens and has a carboxylic group at the end. Thus, in total its 18 carbons and no double bonds 18:0

63
Q

What is the structure of butyric acid?

A

The structure of butyric acid is 4 carbons long with only 3 that can combust as the carboxylic group on the end is already oxidized and will not yield any energy.

64
Q

Where is butyric acid found?

A

This is found in butter and is one of the fatty acids that are produced during fermentation in the large intestine through the microbes.

65
Q

What has a higher GE (gross energy) butyric acid or stearic acid?

A

Stearic acid has a higher GE has it has more carbons which are able to have energy being released from them.

66
Q

Do double bonds reduce or increase the amount of GE in a molecule? Explain oleic acid and stearic acid.

A

Unsaturation and double bonds reduces the gross energy. Oleic acid has a double bond unlike stearic acid which reduces the overall gross energy.

67
Q

What was Atwater’s average GE value for fat determine through a bomb calorimetry?

A

on average for fats the bomb calorimetry had a value of 9.4 kcal/g

68
Q

Why is Atwater’s value of fats indicate. How can this be an issue for fats like butyric fatty acid?

A

They indicate that fats are all long chain and the majority of the structure is saturated with Hydrogens. However, butyric fatty acid only has a GE value of 5.3 and is a short chain of carbons, only have 4 in total and three that can be oxidized.

69
Q

What is the most consistent out of fat, proteins and carbohydrates for non changing values?

A

Sugars and polysaccharides.

70
Q

Is the nutritions facts label based on wet or dry weight?

A

The nutritions fact label is based on wet weight. However, the crude fibre, crude protein, crude fat, minerals and moisture is determine using dry food.

71
Q

Why sometimes does the calorie value not match with calculations using the Atwaters values? (hint….think CHO)

A

This is because in carbs the fibre content does not contribute to digestible energy and will not provide any energy and ATP when consumed.

72
Q

What does dietary fibre refer to?

A

Dietary fibre refers to carbohydrate fibre which is not actually able to be digested in the small intestine. The dietary fibre will be fermented in the small intestine and will produce VFA’s which will be absorbed in the colon and contributes to the metabolize energy value

73
Q

Does soluble or insoluble fibre produce more VFA’s?

A

Soluble fibre produces more violate fatty acids than insoluble fibres.

74
Q

Why is indigestible fibre left on nutrition labels and include in calorie intake?

If a product as a lot of insoluble fibres what can a company do?

A

Indigestible fibres are include in calorie intake because they can be fermented to produce VFA’s which are absorbed in the colon and contribute to the ME value. Likewise, in Atwaters values he included indigestible fibres in his carbohydrate value.

If a product has a high amount of insoluble fibre found within the product it can file a report to Health Canada asking that the insoluble fibre can be removed from the calorie portion of food.

75
Q

What does Heat Increment of Feeding (HIF) mean?

A

This is the obligatory energy that is used when digesting, absorbing and metabolizing nutrients after one ingests a food. This is basically the energy that must be expended by our body in order to obtain the nutrients consumed after a meal.

76
Q

What does the heat increment of feeding include (2)?

A
  1. This includes the amount of energy that is used when digesting, absorbing and metabolizing food
    - this is things like chewing, secretions, motility, amino acid catabolism etc.
  2. The metabolism of nutrients in order to maintain homeostasis.
    Example: when you have a high protein meal you will have a lot of amino acids in the blood so what needs to happen is catabolism of the amino acids to remove them from the blood stream.
77
Q

How do you determine net energy and what does it support?

A 
Net energy (NE) is determine through the subtraction of heat increment of feeding (HIF) from metabolized energy (ME).
NE = ME - HIF

Supports: basal metabolism, growth, pregnancy etc.

78
Q

What is another way to say the heat increment of food (HIF)?

A

The thermic effect of food (TEF)

79
Q

Explain the difference between ME and NE

A

Metabolized energy looks at the energy that is needed for all functions like digestion, absorption, metabolism, and other body functions. Whereas, net energy is looking at the amount of energy that is remaining after digestion, absorption and metabolism that can be used for the rest of the body functions.

80
Q

How much does the heat increment of food (HIF) contribute to the value of metabolized energy (ME)?

How much for each macronutrients

A

The HIF contributes to ~5%-15% of the total ME, on average is 10%.

Fats: ~5%
Carbohydrates: ~10%
Proteins: ~15%

81
Q

What would be the reason for a high HIF value?

A

The reason for a high HIF value would be the consumption of proteins. Proteins take the longest to digest, absorb and metabolized as they have the lowest digestibility of 92% and as a result will require more energy.

82
Q

What is basal metabolic rate?

How many calories do you burn from your basal metabolism

A

Basal Metabolic rate refers to the energy your body is using while you are awake before a meal.

75 Kcalories an hour
1800 Kcalories a day

83
Q

What happens after you consume a meal. SO before a meal you have a basal metabolic rate (75 Kcalories an hour or 1800 Kcalories a day ).

A

After you consume a meal the amount of energy your body is expending is going to be much greater and will peak around 2 hours after a meal. This is the heat production to digest, absorb and metabolize the meal which is the heat increment of food.

The amount of energy you will expend after a meal will vary based on the macronutrients that were consumed during the meal. More protein meals will have higher energy expenditure then a lower protein meal.

84
Q

What are ways that energy is expended in the body (not HIF)? (there are 3)

A

Energy is expended in the body through basal metabolism, physical activity and thermoregulation.

Can also be used for other things like growth and reproduction.

85
Q

Out of the three ways in which net energy can be used which one requires the most energy. Explain.

A

Out of the three ways energy can be expended the one which uses the most energy is basal metabolism, using amount 60% of the net energy. Basal metabolism is the amount of energy your body needs when no other physical activity is taking place. This is the amount your body needs at rest. If you are only consuming enough energy to support your basal metabolism you will not have enough energy for physical activity and respond to hot or cool environments.

86
Q

Explain NE and physical activity.

A

The amount of energy that is expended by a person for physical activity varies significantly amongst individuals. An individual who has an office job will expended less energy for physical activity than one who is doing a lot of physical labour for their job like a construction worker. Before individuals used to use a lot of energy walking and doing work but as desk jobs began to become more dominant the amount of physical activity on average decreased drastically.

87
Q

Can physical activity expend more energy than basal metabolism?

A

Yes but that is when an individual is very active like a pro athlete expends a lot of energy and can have a physical activity expenditure greater than basal metabolism

88
Q

What are modern changes which benefit thermoregulation?

A

When we are in cold temperatures this can activate brown fat which can contribute to weight loss. Likewise, during warm conditions it can increase heat shock proteins and improve cardiovascular diseases.

89
Q

Do human expend more or less energy now for thermoregulation.

A

Humans expend less energy now then before. This is because air conditioning, heating and other high tech clothes helps prevent our need to regulate our body temp.

90
Q

What are metabolizing cells?

Where are these cells found?

A

These are fat free mass and BMR is based on the activity of metabolizing cells.

These cells are found in lean mass, bones and organs. Not fat mass because fat mass does not contribute to a lot of the metabolic activity in adipose tissue

91
Q

Does basal metabolism drop during points of starvation and malnutrition?

A

No basal metabolism will not drop when one is in a point of starvation or malnutrition. In this phase one will be below the BMR which can cause a negative energy balance which can cause weight loss, increase in infection and illness.

92
Q

What will increase or decrease basal metabolic rate?

A

Thyroid gland, hypothalamus, thyroid hormone and pituitary glands.

93
Q

What is Kleiber’s Law and what does it determine?

What is the Kleiber’s law equation?

A

Kleiber’s law determines basal metabolic rates for animals. The conclusion made by Kleiber was that basal metabolic rate varies by body weight by 0.75 exponent. Small animals conserve more energy and expend less due to their lower surface area.

Equation = Metabolic rate and body mass ^0.75

94
Q

What do we use to determine the basal metabolic rate in humans and why can’t we use the Kleiber’s law?

A

Due to the large variation in adipose stores determine the metabolic rate based on weight would not be accurate. An individual could weight 220 pounds with lean tissue which have a lot of metabolize cells which have more metabolized cells and expend more of the net energy. Another individual could weight 220 pounds and have a large amount of that weight be adipose tissue which does not expend a lot of energy because it does not have any metabolized cell. Thus the metabolic rates would differ.

We use Harris-Benedict Equations for BMR. The experiment used to determine the BMR can be argued to give resting metabolic rate (RMR), which give a higher value than BMR. There is on equation for males and one for females which include: height, weight and age.

NOTE it is directly related to height and weight and inversely related to age.

95
Q

What are 5 factors which impact basal metabolic rate?

A
  1. Age: individuals who are younger have lower metabolic rate then individuals who are older.
  2. Genetics: some individuals inherit faster metabolism then others which can be directly related to the thyroid signalling axis.
  3. Gender: men have a higher BMR than females because they have a greater amount of lean body mass than females.
  4. Higher physical activity levels: individuals who are more physically active have a greater lean body mass then individuals who are less physically active and as a result they expend more energy than individuals with a greater amount of adipose tissue.
  5. Temperature: environments that put a lot of stress on thermoregulation like heat and cold can cause an increase in basal metabolic rate through cold temperatures activating brown fat or hot temperatures causing the release of heat shock proteins. (not temperature does not directly impact BMR but the alteration in physiology is what causes the change.
96
Q

Is bomb calorimetry an example of direct or indirect calorimetry?

A

Bomb calorimetry is an example of direct calorimetry to determine the amount of energy that can determine the amount of energy present in food and the amount of energy expended.

97
Q

What is insensible heat loss?

A

Insensible heat loss is the loss of heat through sweat or vapour in expired air and needs to be added to sensible heat loss like change in heat. Change in water vapour is insensible heat loss.

98
Q

change in heat is sensible or insensible heat loss?

A

Sensible heat loss. Can directly calculate this.

99
Q

change in water vapour is sensible or insensible heat loss?

A

Insensible heat loss.

100
Q

What does indirect calorimetry require the measurements of?

A

Oxygen used, carbon dioxide produced and the urinary nitrogen excreted.

101
Q

Can we use heat expenditure to determine oxygen used and CO2 produced?

A

Yes research has found that they can be used to determine the amount oxygen used and CO2 produced through respiration (cellular respiration which is used to break down bonds and release energy) and the amount of nitrogen (from proteins which are released in the urine.

102
Q

What can indirect calorimetry measure?

A

The total amount of energy expended and the amount used by each macronutrients.

NUTR*3210 (8 decks)

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