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Anatomy Exam 3 > Lecture 10 : Gastrointestinal System IV : Nutrition and Metabolism I > Flashcards

Lecture 10 : Gastrointestinal System IV : Nutrition and Metabolism I Flashcards

1
Q

Nutrient =

A

substance in food the body uses to promote normal growth, maintenance and repair

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2
Q

Categories of nutrients (5):

A

Macronutrients = fats, carbohydrates and proteins (make up most of what we eat)

Micronutrients = vitamins and minerals (required in smaller quantities)

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3
Q

Essential nutrients =

A

body can’t make as fast as we need – must be obtained through diet

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4
Q

Nonessential nutrients =

A

also vital for normal functioning, but body can synthesize through interconversions of one type of molecule to another

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5
Q

The ______ regulates the Nutrition Facts label

A

U.S. Food and Drug Administration (FDA)

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6
Q

Nutrition labels help us understand:

A

types of nutrients included in a packaged food

recommended serving size

number of calories per serving

whether we’re getting enough of the nutrients our bodies need
(% daily recommendations)

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7
Q

Nutrition labels are based on basal metabolic needs of an average person =

A

~2000 Calories/day

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8
Q

The energy value of foods is measured in _____

A

kilocalories

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9
Q

1 kilocalorie =

A

energy to raise temperature of 1 kg water by 1 degree C

1 kcal = 1 calorie (from nutrition labels)

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10
Q

Nutrient content of foods:

A

Carbohydrates = 4 kcal/gram
Protein = 4 kcal/gram
Fats = 9 kcal/gram

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11
Q

Metabolic rate =

A

number of kcal used per hour

varies depending on multiple factors:
activity, hormones, age

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12
Q

Carbohydrates
Dietary Sources:

A

sugars
starch
glycogen

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13
Q

Sugars =

A

(mono- and disaccharides) - most from plants

Fruits, sugar cane, sugar beets, honey, (exception: milk sugar)

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14
Q

Starch =

A

(polysaccharides)

Grains & vegetables

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15
Q

Glycogen =

A

negligible amount from meats

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16
Q

GLUCOSE

A

the body’s main fuel source for ATP production

Brain and red blood cells use glucose for energy

Either used or stored (glycogen and/or fat)

Other monosaccharides converted to glucose in liver

Pentose sugars in RNA, DNA, sugars in glycocalyx

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17
Q

POLYSACCHARIDES as sources of fiber:

A

Insoluble fiber – cellulose from vegetables (roughage) : increase bulk of stool

Soluble fiber – pectin from apples, citrus : balances blood cholesterol, sugar

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18
Q

Dietary Considerations =
____ of total calorie intake – ideally complex carbohydrates

A

45-65%

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19
Q

Dietary Considerations =
Get plenty of fiber _____

A

(25-30 gm/day)

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20
Q

Dietary Considerations =
Highly processed carbohydrates (candy, soda) – concentrated energy source without ______

A

benefits of other nutrients (empty calories)

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21
Q

Proteins

A

Made from 20 amino acid building blocks

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22
Q

9 out of the 20 proteins are _______ because we can’t synthesize them

A

essential amino acids

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23
Q

Dietary Sources:
Complete proteins =

A

contain all the essential amino acids for tissue maintenance and growth

Eggs, milk, fish, most meats, soybeans

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24
Q

Dietary Sources:
Incomplete proteins =

A

(lack one or more essential aa)

Legumes (peas & beans), nuts, cereal grains

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25
Q

Use amino acids to build proteins or burn for energy depending on:

A

All or none rule – all necessary amino acids must be present to make a protein – unused aa oxidized for energy or converted to carbs or fats

Used for ATP production if not enough carb or fat calories in diet

Anabolic hormones stimulate protein synthesis & growth, stress hormones (cortisol) break down protein and convert amino acids to glucose

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26
Q

Nitrogen balance =

A

rate of protein synthesis equals rate of protein breakdown and loss (healthy adults)

Positive balance during growth, pregnancy; negative balance during stress, starvation

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27
Q

Will vary based on age, size, metabolic rate and need (state of nitrogen balance); generally _____ – need to get essential amino acids from diet

A

~0.8 gm/kg body weight

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28
Q

Gluten sensitivity – Celiac disease (genetic) =

A

gluten breakdown products stimulate immune cells that attack intestinal epithelium – damage villi, decrease surface area for absorption - leads to malabsorption

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29
Q

_____ the most abundant dietary lipid

A

Triglycerides

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30
Q

Structure of _____ determines whether are solids or liquids at room temperature

A

fatty acid chain

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31
Q

Body’s most efficient and compact form of stored energy

A

lipids

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32
Q

Saturated fats =

A

(more H atoms, single bonds, solid at room temp)

Meat, dairy, coconut, hydrogenated oils

(trans fats: margarine or solid shortening)

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33
Q

Unsaturated fats =

A

(one or more double bonds, oils – liquid at room temp)

Seeds, nuts, olive oil, vegetable oils

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34
Q

Cholesterol =

A

(not used for energy)

Egg yolk, meat, organ meat, shellfish, milk products

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35
Q

____ are good fuel sources and are critical for normal cell physiology

A

Lipids

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36
Q

lipid uses in the Body:

A

Protect from heat loss, cushion body organs, energy store

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37
Q

____ create myelin and cell membranes

A

Phospholipids

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38
Q

___ precursor to hormones, stabilizes cell membranes

A

Cholesterol

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39
Q

Triglycerides are major fuel source for ______

A

skeletal muscle & hepatocytes

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40
Q

Presence of fats in diet aids in absorption of_____

A

fat-soluble vitamins

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41
Q

Dietary Considerations:
____of total calorie intake should be lipids

A

20-35%

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42
Q

Saturated should be less than ___ of total fat intake

A

10%

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43
Q

Limit cholesterol in diet – _____ makes 85% of what we use

A

liver

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44
Q

Liver can’t make 2 essential FA:

A

linoleic acid (omega-6 FA)

linolenic acid (omega-3 FA)

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45
Q

___ is vital for the proper function of the human body

A

Cholesterol

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46
Q

Cholesterol -
Not used as energy source, but is important precursor molecule for:

A
  • Bile salts
  • Steroid hormones including:
    testosterone
    estrogen
    aldosterone
    cortisol
  • Vitamin D
47
Q

Cholesterol is an integral part of __________

A

plasma membranes

48
Q

15% of blood cholesterol comes from _____

A

diet

49
Q

85% of blood cholesterol is synthesized by _____

A

liver

50
Q

Cholesterol is broken down by liver and excreted in ____

A

bile

51
Q

Recommended total blood cholesterol =

A

< 200 mg/dl

52
Q

high cholesterol is correlated with:

A

atherosclerosis, strokes and heart attacks

53
Q

how cholesterol is packaged in blood is more important clinically as predictor of ______

A

cardiovascular health

54
Q

“good” cholesterol

A

HDL > 60 mg/dl is protective

55
Q

“bad cholesterol”

A

LDL > 160 mg/dl is undesirable

56
Q

_____ are considered a better predictor of cardiovascular disease

A

LDL levels

57
Q

_____ :cholesterol lowering drugs routinely prescribed for cardiovascular health

A

Statins

58
Q

Lipoproteins =

A

triglycerides and cholesterol are both insoluble in water, so transported in blood by lipid-protein complexes called lipoproteins which vary in structure and function

have varying amounts of phospholipids & proteins in their structure – accounts for “density”

59
Q

Chylomicrons =

A

transport digested fats to liver

Very low-density lipoproteins – carries triglycerides from liver to adipose tissue

60
Q

Low-density lipoprotein (LDL) =

A

carries cholesterol from liver to tissues

61
Q

High-density lipoprotein (HDL) =

A

carries cholesterol from tissues to liver for breakdown; also prevents cholesterol from accumulating on artery walls

62
Q

Diet and lifestyle can influence ____ levels

A

cholesterol

63
Q

___ continues to make cholesterol, even when present in diet

A

Liver

64
Q

________ in diet stimulate liver synthesis of cholesterol and inhibit its excretion from body

A

Saturated fats

65
Q

_____ enhance excretion of cholesterol and conversion to bile salts, so decrease total cholesterol levels

A

Unsaturated fats (olive oil, most vegetable oils)

66
Q

Trans fats (hydrogenated oils) _____ LDLs and _____ HDLs

A

increase

decrease

67
Q

Cigarette smoking and stress ___ HDL levels

A

lower

68
Q

Aerobic exercise ____ HDL levels

A

increases

69
Q

Vitamins =

A

Required in small amounts for growth and good health

Serve as co-enzymes in metabolic reactions

Balanced diet best way to ensure adequate intake

70
Q

Co-enzymes =

A

act with enzymes to accomplish a chemical task

71
Q

Most vitamins are not made by body – must be ingested through food or supplements:

A

Exceptions: vitamin D made in skin; some B vitamins & vitamin K – gut bacteria

Body can convert beta-carotene into vitamin A

72
Q

Water soluble vitamins =

A

B complex vitamins and vitamin C
Absorbed in intestines

Exception: Vitamin B12 – intrinsic factor complex binds to receptor

Not stored, excess excreted in urine

73
Q

Fat soluble vitamins =

A

Vitamins A, D, E and K

Absorbed with dietary lipids in gut

Are stored in body (except vitamin K)

Excess can result in toxicity

74
Q

Most minerals are ionized in body fluids or bound to organic compounds to form _____

A

phospholipids, hormones and various proteins

75
Q

Best sources of minerals:

A

legumes, vegetables, milk, some meats

76
Q

____ is the sum of all biochemical reactions in the body

A

Metabolism

77
Q

Two classes of Metabolic Processes :

A

Anabolism

Catabolism

78
Q

Anabolism =

A

reactions that build larger molecules from smaller ones

e.g. combining individual amino acids to make proteins

79
Q

Catabolism =

A

processes that break down complex structures to simpler parts

e.g. hydrolysis of foods in GI tract

e.g. glycolysis : breakdown of glucose for ATP production

80
Q

Nutrients are involved in ______ reactions

A

both anabolic and catabolic

81
Q

Anabolic processes build:

A

Proteins
Glycogen
Triglycerides

82
Q

Catabolic processes include:

A

Glycolysis
Citric Acid Cycle
Oxidative Phosphorylation

83
Q

_____ is the pivotal fuel molecule in the ATP producing pathways

A

Glucose

84
Q

1) Glycolysis

A

Glycolysis, in the cytosol, breaks down each glucose molecule into two molecules of pyruvic acid

85
Q

2) Citric Acid Cycle

A

Pyruvic acid then enters the mitochondrial matrix, where the citric acid cycle oxidizes it to CO2

substrate-level phosphorylation forms small amounts of ATP

86
Q

3) Electron Transport Chain & Oxidative Phosphorylation

A

Energy-rich electrons picked up by coenzymes are transferred to the electron transport chain, built into the inner mitochondrial membrane

electron transport chain carries out oxidative phosphorylation, which generates most of the ATP in cellular respiration

87
Q

Two techniques are used for ATP synthesis:

A

substrate-level phosphorylation

oxidative phosphorylation

88
Q

substrate-level phosphorylation:

A

a high-energy phosphate group is transferred directly from a substrate to ADP to form ATP

occurs in the cytosol and mitochondrial matrix

89
Q

oxidative phosphorylation:

A

electron transport proteins “pump” protons = creating a proton gradient

ATP synthases uses the energy of the proton gradient to bind phosphate groups to ADP

occurs only in the mitochondrial matrix

90
Q

_____ play a key role in metabolism

A

Coenzymes

91
Q

Two key coenzymes (derived from the B vitamins niacin and riboflavin) serve as carriers of high energy electrons for oxidative phosphorylation:

A

Nicotinamide adenine dinucleotide (NAD+)

Flavin adenine dinucleotide (FAD)

92
Q

Coenzymes play a role in Oxidation-Reduction (Redox) Reactions:

A

Oxidation –can be defined as the gain of oxygen or loss of hydrogen; when a substance is oxidized, it loses electrons (loses energy) as they move to a substance that more strongly attracts them

Reduction – when a substance gains electrons (gains energy) it is said to be reduced

93
Q

Glycolysis converts one glucose molecule into
______

A

2 pyruvic acid molecules

94
Q

____ does not require oxygen: ____ process so occurs whether or not oxygen is present

A

Glycolysis

anaerobic

95
Q

Glycolysis phases =

A

Phase 1 uses energy (2 ATP):

Phase 2 forms 2 3-carbon molecules

Phase 3 transfers hydrogen with high energy electrons to coenzyme carriers and forms 4 ATP

96
Q

Yield from 1 glucose molecule:

A

2 pyruvic acid molecules (C3H4O3)

2 net ATP molecules

2 reduced coenzymes: 2 X (NADH + H+)

97
Q

Anatomy of a mitochondrion
Two “compartments”:

A

Intermembrane space : between inner and outer membranes

Mitochondrial matrix : inside inner membrane

98
Q

The ____ occurs in the mitochondrial matrix

A

citric acid cycle

also called TCA cycle or Kreb’s cycle

99
Q

citric acid cycle

A

If oxygen present, pyruvic acid enters the mitochondria

Pyruvic acid converted to acetyl CoA

Coenzyme A is another coenzyme derived from a B vitamin – it is used to shuttle 2-carbon acetic acid into citric acid cycle

100
Q

Reactions during this process (citric acid cycle):

A

removal of carbon which is released as carbon dioxide (CO2 )

formation of more reduced coenzymes

PO4 passed from GTP to ADP (substrate level phosphorylation)

101
Q

Glucose formed 2 pyruvic acid molecules and each goes through the cycle, so total yield from 1 glucose:

A

6 CO2
10 reduced coenzymes
2 ATP molecules

102
Q

Energy carried by reduced coenzymes is harvested at the _____

A

electron transport chain

103
Q

The electron transport chain is a series of______

A

proteins on the inner mitochondrial membrane

104
Q

Coenzymes from glycolysis and the citric acid cycle get ____ here when their hydrogen is stripped off at electron transport chain

A

oxidized

105
Q

Each hydrogen atom is then split into a _____

A

proton (hydrogen ion, H+) and an electron

106
Q

electron transport chain =

A

Electrons are passed down the chain, with a stepwise reduction in energy along the way

The released energy is used to pump protons into the intermembrane space

Electrons are combined with oxygen and hydrogen ions to form water

Oxygen is required for this to happen

107
Q

Activity of the electron transport chain leads to the creation of a:

A

proton gradient across the inner membrane

108
Q

Proton movement down its gradient drives _____

A

ATP synthesis

109
Q

protons move down their gradient through a membrane protein coupled to a rotary motor called _____

A

ATP synthase

110
Q

The spinning rotor catalyzes the binding of ADP and Pi to form ___

A

ATP

111
Q

Oxidative Phosphorylation:

A

Oxidation of coenzyme carriers is coupled to phosphorylation of ADP to create ATP

112
Q

Oxidative Phosphorylation
Steps:

A

1) Reduced coenzymes (NADH+ H+ FAH2) deliver electrons to respiratory enzyme complexes I and II

2) the electrons are transferred from one complex to another in the membrane (each complex is reduced and then oxidized)

3) at respiratory enzyme complex IV, electron pairs combine with two protons (H+) and a half molecule of O2, forming water

4) ATP synthase (complex V) harnesses the energy of the proton gradient to synthesize ATP.
As H+ flows back across the membrane through ATP synthase, the synthase rotor spins, causing Pi to attach to ADP, forming ATP

113
Q

one glucose molecule yields about ____ following oxidative phosphorylation

A

30 ATP

114
Q

To fully utilize protein or fat as an energy source, we have to convert it into a substrate utilized by the ____

A

mitochondria

Anatomy Exam 3 (11 decks)

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