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Nutrition > Unit 7: Metabolism Of Nutrients And Energy Balance > Flashcards

Unit 7: Metabolism Of Nutrients And Energy Balance Flashcards

1
Q

Explain the role of Adenosine Triphosphate (ATP) in the body

A

-Energy associated is transferrred to chemical bonds of ATP
-Formed from Adenosine Diphosphate (ADP) and a free phosphate
ADP + P + energy = ATP (requires energy)
-The high energy phosphate bonds of ATP can be broken to release free energy
ATP –> ADP + P + energy for body cells

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2
Q

How efficient is the conversion of the chemical energy of food to the chemical energy of ATP?

A

~50%

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3
Q

What is the energy from ATP used for?

A
  • Movement (muscles)
  • Synthesizing compounds
  • Transporting nutrients
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4
Q

ATP has 3 phosphate groups. The negative charges on the phosphate groups make ATP vulnerable to what?

A

Hydrolysis
When the bonds between the phosphate groups are hydrolyze they break , splitting into one or two phosphate groups and releasing energy

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5
Q

Often, the hydrolysis of ATP occurs simultaneously with reactions that will use that energy. This is known as?

A

Coupled Reactions

Body uses ATP to transfer the energy released during catabolic retractions to power anabolic reactions

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6
Q

Define Catabolism

A

Breaking down of body compounds

Release energy

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7
Q

Define Anabolism

A

Creation of body compounds
Require energy
Ex. Making of glycogen, triglycerides, protein

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8
Q

Explain Glycolysis

A
  • Preliminary phase of glucose catabolism
  • Occurs in Cytoplasm of cell
  • Results in: splitting glucose (6-carbon) into 2 pyruvate (3-carbon)
  • Anaerobic (does not require oxygen)–important source of energy when oxygen is limited
  • Yields small amount of ATPl
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9
Q

Under Anaerobic conditions what happens to Pyruvate?

A
  • Yields energy quickly but cannot be sustained
  • Converted to lactic acid
  • Lactic acid is converted back to pyruvate after rest or travels to the liver to be converted back to glucose.
  • The glucose can then be used by muscle cells to replenish glycogen or produce energy aerobically again
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10
Q

Under aerobic conditions what happens to pyruvate?

A
  • Energy expenditure is slower paced
  • Pyruvate breaks down to Acetyl CoA
  • Total energy yield is greater and can be sustained
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11
Q

Explain the functions of Acetyl CoA

A
  1. Synthesize Fats: efficient way to store energy, glucose, fatty acids, amino acids can be used to make Acetyl CoA and therefore fat
  2. Generate ATP: Acetyl CoA proceeds through TCA cycle, releasing energy in its C-C bonds and hydrogens with their electrons to the electron transport chain
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12
Q

Explain the Tricarboxylic Acid (TCA) cycle a.k.a. The Krebs cycle

A
  • requires oxygen
  • second stage of glucose catabolism
  • occurs in mitochondria of the cell
  • generates ~94% of energy from glucose
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13
Q

Explain the steps of the TCA cycle

A
  1. Oxaloacetate (compound made from pyruvate) starts the TCA cycle
  2. Oxaloacetate (4-carbon) combines with Acetyl CoA (2-carbon) to make 6-carbon compound
  3. This compound is changed to a 6-carbon compound that release CO2 becoming a 5-C, then 4-C compound
  4. The original 4-C Oxaloacetate is formed again and picks up a new Acetyl CoA
  5. The breakdown of Acetyl CoA releases hydrogens with their electrons which are carried by coenzymes made from B vitamins to the electron transport chain
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14
Q

What B vitamins are required by the TCA cycle?

A
  1. Thiamin
  2. Niacin
  3. Pantothenic Acid
    All 3 are essential components of coenzymes TPP, NAD, and CoA
  4. Riboflavin
  5. B12
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15
Q

What is produced from 1 cycle of the TCA cycle? (2 Acetyl CoA)

A
  1. 4 CO2
  2. 4 pairs of hydrogen ions: H+
  3. 2 FADH2
  4. 6 NADH + H+
  5. 2 GTP
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16
Q

What are the products of glycolysis?

A
  1. 4 ATP (Net 2 ATP because 2 ATP are used to begin reaction)
  2. 4 NADH + H+
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17
Q

Explain the Electron Transport Chain

A

-Final stage of glucose catabolism
-transfer of electrons from one coenzyme to another in an oxidation-reduction process
-Phosphorylation of ADP to ATP (Oxidative phosphorylation)
-Hydrogen is combined with oxygen to produce water
C6H12O6 + 6O2 –> 6CO2 + 6H2O + energy (ATP)

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18
Q

Define Deamination

A

Removal of an amino group from an amino acid or other compound

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19
Q

Explain Oxidative Phosphorylation

A

ADP and P are combined (requiring oxygen) to form ATP

ATP is Phosphorylated

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20
Q

What is the ATP production from the Electron Transport Chain?

A

28 ATP

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21
Q

What is the total ATP production from Glucose metabolism

A 
Electron Transport Chain: 28 ATP
Glycolysis: 2 ATP
GTP: 2 ATP
-----------------------------------
Total: 32 ATP
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22
Q

Why might the total ATP production be 30 ATP?

A

The NADH + H+ generated in the cytoplasm during glycolysis pass electrons to shuttle molecules which move them to the mitochondria. One shuttle, malate, contributes electrons to the Electron Transport Chain before the first site of ATP synthesis, yielding 5 ATP. Another, glycerol phosphate, adds its electrons to the chain beyond that first site, yielding 3 ATP. Thus, sometimes 5 or 3 ATP result from glycolysis

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23
Q

Explain Gluconeogenesis

A

Making glucose from noncarbohydrate sources.
The glycerol portion of a triglyceride (3-carbon) and most amino acids can be used. Fatty Acids (2-carbon) cannot be used. Liver is the major site of gluconeogenesis but the kidneys become involved under certain circumstances (Starvation)

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24
Q

Fatty acids are ensymatically combined catabolized by combining with CoA, where each chain is cleaved at the second carbon forming multiple units of Acetyl CoA. This is known as?

A

Beta-Oxidation or Fatty Acid Oxidation

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25
Q

Glycerol to Pyruvate

A

Glycerol is a 3-C compound and so can be easily converted to other 3-C compounds. It can therefore, go either “up” to form glucose or “down” to from pyruvate then Acetyl CoA

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26
Q

Fatty Acids to Acetyl CoA

A

2 carbon fragments from fatty acids combine with CoA to from Acetyl CoA. As each 2-C fragment breaks off hydrogens and their electrons are released and carried to the electron transport chain by coenzymes made from the B vitamins Riboflavin and Niacin

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27
Q

Beta-Oxidation of Palmitic Acid

A

C16 + CoA –> C14 + Acetyl CoA + 2 hydrogen pairs
C14 + CoA –> C12 + Acetyl CoA + 2 hydrogen pairs
C12 + CoA –> C10 + Acetyl CoA + 2 hydrogen pairs
Hydrogens are picked up by NAD and FAD which act as carriers in the ETC in the production of ATP. The Acetyl CoA enters the TCA cycle and generates more hydrogen pairs for ATP production

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28
Q

The extraction of energy from fats (beta-oxidation and TCA cycle) are dependent on what? This means that aerobic exercise is recommended for?

A

Dependent on oxygen

Recommended for burning of body fat and weight control

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29
Q

During anaerobic exercise what is halted?

A

Fat catabolism

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30
Q

About how much total energy from fat oxidation comes through beta-oxidation?
Through TCA cycle?

A

Beta -oxidation: 0.25

TCA cycle: 0.75

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31
Q

Triglycerides from food or stored as fat are excellent sources of energy as ATP, built are a minor source of glucose why?

A

Because most of a triglyceride molecule is made of fatty acids

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32
Q

The primary role of Amino Acids is protein synthesis; they are only catabolized when: (3)

A

1, Insufficient energy or glucose

  1. Excess of protein for body requirements
  2. Proteins are of such poor quality that protein synthesis is curtailed
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33
Q

Amino acids are deaminated before then enter the pathways of energy production/storage. Describe deamination, and its products

A

Enzymatic removal of the amino group from the amino acid; resulting in production of ammonia. Requires Vitamin B-6, riboflavin and niacin. Ammonia is combined with CO2 by the liver to form urea which is then excreted in the urine by the kidneys

34
Q

Why is the production of urea important?

A

Urea is far less toxic than ammonia

35
Q

An amino acid can enter the metabolic pathways through pyruvate, Acetyl CoA or certain intermediates of the TCA cycle, depending on what?

A

The carbon-skeleton of the amino acid

36
Q

Only amino acids that can be converted to Pyruvate can produce glucose through what?

A

Gluconeogenesis

37
Q

Approximately how many amino acids are potential sources of glucose?

A

~0.5 of the amino acids

38
Q

Unlike fat, amino acids are…

A

A fairly good source of glucose in the absence of carbohydrates

39
Q

The body is more efficient at storing excess dietary fat as body fat than…

A

Converting excess carbohydrate/protein to body fat

40
Q

Body proteins from muscle and lean tissue start to be catabolized when glycogen stores are depleted and no carbohydrates are available. This happens:

A

After several hours of fasting or low carb dieting

41
Q

A high intake of protein may be provided by a diet very low in carbohydrate, a high intake of protein cannot prevent what?

A

Loss of body protein

42
Q

Define Ketone bodies

A
  • normal metabolites of the body

- at low production the body can metabolize

43
Q

Explain how Ketosis occurs

A
  • during fasting or low-carb dieting
  • lack of carbohydrate stimulates breakdown of fatty acids
  • Acetyl-CoA accumulates because there is insufficient oxaloacetate
  • Acetyl-CoA cannot form citric acid in TCA cycle
  • Acetyl-CoA fragments condense to form ketone bodies
  • Ketone bodies reach high concentration in blood
44
Q

Who can Ketosis happen to?

A
  • untreated diabetes

- starved for glucose

45
Q

What are some characteristics of Ketosis?

A
  • acetone breath (sweet smelling)
  • suppresses appetite
  • increases urine output
  • causes nausea
46
Q

What are some consequences of severe Ketosis?

A
  • Acidosis (low pH of blood)
  • Loss of water from body tissue (to excrete Ketones)
  • Sodium and potassium become depleted
  • Blood pressure drops
  • Death can result from collapse of circulatory system
47
Q

Define Direct Calorimetry

A
  • actual measurement of energy as heat
  • using a bomb calorimeter it calculates the energy in foods by measuring total amount of heat released after complete combustion
  • can also be used to measure energy expenditure of a person (total amount of heat released)–this requires a specially designed chamber and is expensive
48
Q

Define Indirect Calorimetry

A
  • measurement of oxygen consumption and carbon dioxide production to determine the amount of energy used by the body
  • requires of portable respiration device–less expensive
  • allows for a measurement of a wider range of physical activities
49
Q

Define Gross Energy Values

A
  • Amount of energy determined by a bomb calorimeter when food is burned
  • In the body energy from food is less than gross energy value because some is excreted in feces and urine (incomplete digestion/absorption)
50
Q

Define Physiological Fuel Values and list them

A 
-mathematical adjustment from gross energy values to better represent amount of energy available in the body 
Carbohydrates: 4
Lipids: 9
Protein: 4
Alcohol: 7
51
Q

List the gross energy values

A

Carbohydrates: 4.10
Lipids: 9.45
Protein: 5.65
Alcohol: 7.10

52
Q

Explain Satiety

A
  • hormonal regulated but also influenced by nutrient composition of the diet
  • Protein has greatest satiety because it takes longer to digest (glucose levels constant)
  • High-fibre foods also provide satiety
  • High-fat foods are not satiating but provide a concentrated source of glucose
53
Q

Explain Energy Density

A

-fat and high-sugar/ refined white sugar are high energy-density foods. It is easy to consume a lot of high-energy dense foods before satiation causes eating to stop

54
Q

Explain the function of water to satiety

A
  • Water dilutes food energy
  • High-water content foods (soups, salads, fruit) have a low energy density
  • A small amount if food needs to be consumed to induce satiety
  • A combination of high fibre and water content gives low energy density
55
Q

Define Basal Metabolism

A
  • Basal Metabolic Rate (BMR)
  • minimum energy required to maintain vital life processes
  • Measurement of BMR usually done in the morning under specific conditions
56
Q

List the conditions of which BMR is measured

A
  1. Morning
  2. Subject is awake
  3. 12-15 hours after eating (absence of digestion/absorption)
  4. Lying quietly with complete physical and mental rest
  5. Room temperature (~25 degrees)
  6. Subject is wearing light clothing
57
Q

What factors can increase BMR?

A
  • height
  • growth
  • body composition (gender)
  • fever
  • stresses
  • environmental temperature (both heat and cold)
  • hormones (gender)
  • smoking
  • caffeine
58
Q

What factors can decrease BMR?

A
  • age
  • fasting/starvation
  • malnutrition
  • sleep
59
Q

Explain how BMR can be increased by exercise

A
  • certain types of exercise can also build lean muscle mass
  • leaner the body tissue the higher the BMR
  • Exercise is emphasized in maintaining BMR for weight control
60
Q

Define Thermic Effect of Food

A

The energy required to digest, absorb, transport, metabolize, and store nutrients from food
(Rise in body temperature after a food is consumed)
Depends on macronutrients (Protein foods create the greatest thermos effect)
~10% of total energy intake is estimated for the Thermic effect of food

61
Q

Explain Thermogenesis

A
  • additional energy expended when a person must adapt to chaining circumstances (dramatically)
  • Known as adaptive thermogenesis
  • It is so variable and specific to individuals it is not included when calculating energy requirements
62
Q

How to measure BMR?

A 
Men = 1 kcal/kg body weight/hour
Women = 0.9 kcal/kg body weight/hour
63
Q

How to measure energy expenditure from physical activity?

A 
Physical activity
=40-50% BMR sedentary work 
=55-65% BMR light work
=65-70% BMR moderate work 
=120-140% BMR for heavy work
64
Q

Define Resting Metabolic Rate (RMR)

A

-measure of energy output similar but slightly higher than BMR because its criteria for recent food intake and physical activity are not as strict

65
Q

What are the Thermic effects of the macronutrients

A

Carbohydrates: 5-10%
Fat: 0-5%
Protein: 20-30%
Alcohol: 15-20%

66
Q

Explain Body Mass Index (BMI)

A
  • anthropometric measure based on relationship of body weight to height
  • high correlation to body fat
  • suitable only for people between 20-65 years old
  • not valid for pregnant, breastfeeding, or muscular athletes
67
Q

The lowest mortality rates are associated with a BMI of?

A

20-25

68
Q

Risk of health problems increases with a BMI above or below?

A

18.5-25

69
Q

As BMI increases so does the risk of?

A

Obesity-related diseases (diabetes, cardiovascular)

70
Q

What is the draw pack of measuring BMI?

A

Tells nothing of body composition

71
Q

Explain Percent Body Fat

A
  • measured by hydrodensitometry or bioelectrical impedance (specialist purposes)
  • measured by skin fold
72
Q

Explain the Skin Fold Test

A
  • used to measure percent body fat
  • provides rough approximation
  • measures thickness of fold of skin using a special caliper
  • two most common sites: triceps and subscapular
  • measure is compared to appropriate standard
73
Q

Waist measurements

A
  • indicator of health risks from high body fat
  • measured at narrowest part of trunk (navel)
  • provides indication of fat stored in the abdominal area (visceral fat)
74
Q

Apple-shaped people have a higher risk of?

A

Chronic disease (type 2 diabetes, heart disease, hypertension, breast cancer)

75
Q

Abdominal fat is easier to lose through diet and exercise than fat stored in hip area. TRUE OR FALSE?

A

TRUE

76
Q

What waist circumference is associated with higher risk of disease?

A

Men: greater than 102 cm (40 inches)
Women: greater than 90 cm (35 inches)

77
Q

Obstetrics in abdominal or upper region of the body is a strong predisposing condition to diabetes and cardiovascular disease. TRUE OR FALSE?

A

TRUE

78
Q

What is the basic cause of obesity sometimes referred to as?

A

Obesogenic environment: ur environment has been designed to maximize weight gain

79
Q

When might a person be considered underweight?

A

10% or more below ideal body weight

80
Q

Approximately what percentage of girls/women between the ages of 14-24 have an eating disorder?

A

5%

81
Q

What are some causes of being underweight?

A
  • insufficient consumption of quality and quantity of food
  • poor absorption/utilization of food consumed
  • wasting diseases (TB, AIDS, hyperthyroidism, cancer which increase BMR)
  • excessive physical activity
  • psychological/emotional disorders
82
Q

What are some risks of being underweight?

A
  • nutrient deficiencies
  • anemia
  • higher risk of infection and disease
  • retarded growth
  • amenorrhea (cessation of menstruation)
  • chronic fatigue
  • heart irregularities
  • hypotension
  • psychological problems
  • complications in pregnancy

Nutrition (12 decks)

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