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Exercise Physiology > Chapter 2 > Flashcards

Chapter 2 Flashcards

1
Q

What are substrates?

A

fuel sources from which we make energy

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2
Q

What are the 3 sources of fuel?

A

carbohydrates, fats, and proteins

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3
Q

What are bioenergetics?

A

chemical pathways that convert substrates to energy

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4
Q

What level are bioenergetics performed at?

A

the cellular level

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5
Q

What is metabolism?

A

chemical reactions in the body

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6
Q

How is energy measured in biological systems?

A

calories

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7
Q

What does 1 calorie (1 cal) = ?

A

the amount of heat energy needed to raise 1 g of water 1 degree celsius

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8
Q

How is energy expressed in humans?

A

kilocalories (kcal)

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9
Q

1 kcal = ?

A

1,000 cal, which also = 1 Calorie (dietary)

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10
Q

How is energy used in myofibrils?

A

it causes the sliding of actin and myosin filaments resulting in muscle action and force generation

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11
Q

When is energy released?

A

when chemical bonds are broken

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12
Q

Why is food not used directly for cellular operations?

A

the molecular bonds in substrates are weak and provide little energy when broken

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13
Q

How is energy in food’s molecular bonds released?

A

they are chemically released within our cells and then stored in the form of ATP

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14
Q

What energy does the body need at rest?

A

50% carbs and 50% fats

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15
Q

What substrate provides little energy for metabolism?

A

proteins

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16
Q

How do proteins help with energy?

A

important for enzymes that aid chemical reactions and are structural building blocks

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17
Q

During intense, short-term exercise, what substrate is being used?

A

more carbs are used

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18
Q

During longer, less intense exercise what substrate is being used?

A

more fats and less carbs

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19
Q

What percentage of carbs are being used in high intensity exercise?

A

95% CHO

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20
Q

What is a major benefit of HIIT training

A

a bigger calorie expenditure compared to continuous exercise

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21
Q

What substrate is used more in anaerobic exercise?

A

carbs

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22
Q

What substrate is used more in aerobic exercise?

A

fats

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23
Q

What are all carbs converted to?

A

glucose

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24
Q

How much energy do carbs give you?

A

4.1 kcal/g

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25
Q

How many kcals of carbs are stored in the body?

A

2500 kcals

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26
Q

Where is extra glucose stored in the body?

A

the liver and muscle

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27
Q

What is the extra glucose in the liver and muscle called?

A

glycogen

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28
Q

Where is glycogen stored?

A

in the cytoplasm of muscle cells until those cells use it to form ATP

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29
Q

When are muscle and liver glycogen stores limited?

A

when the diet has an insufficient amount of carbs and can be depleted during prolonged, intense exercise

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30
Q

What do we rely on to replenish our carb reserves?

A

starches and sugars

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31
Q

What happens to muscles when there isn’t a sufficient carb intake?

A

muscles are deprived of their primary energy source

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32
Q

What energy source is used by brain tissue?

A

carbs

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33
Q

Severe carb depletion causes what in the brain?

A

negative cognitive effects

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34
Q

How do fats contribute to energy?

A

they provide a large portion of energy used in prolonged, less intense exercise

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35
Q

How much energy do fats give you?

A

9.4 kcals/g

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36
Q

How many kcals of fats are stored in the body?

A

+70,000 kcal stored in the body

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37
Q

Why is fat less readily available for cellular metabolism?

A

it must be broken down to its basic components of glycerol and 3 free fatty acids (FFAs)

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38
Q

What is only used in fats to form ATP?

A

FFAs

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39
Q

How does fat have a high net ATP yield?

A

more energy is derived from breaking down a gram of fat than from the same amount of carbs

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40
Q

Why can’t fat meet all the energy demands of intense muscular activity?

A

the rate of energy released from fat is too slow

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41
Q

When is protein used as an energy source?

A

in the case of severe energy depletion

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42
Q

What does protein need to be converted to before it produces energy?

A

glucose

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43
Q

What is gluconeogenesis?

A

when protein or fat is converted into glucose

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44
Q

What is lipogenesis?

A

the process of converting protein into fatty acids

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45
Q

Why is lipogenesis used?

A

for energy storage and cellular energy substrate

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46
Q

What percentage of energy can protein supply to the body to sustain prolonged exercise?

A

10%

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47
Q

What basic unit of protein can be used for energy?

A

amino acids

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48
Q

How much energy does protein give you?

A

4.1 kcal/g

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49
Q

Free energy has to be released from what?

A

chemical compounds at a controlled rate

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50
Q

What is the controlled rate determined by?

A

the availability of the primary substrate and enzyme activity

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51
Q

What does the availability of a substrate do for the controlled rate?

A

it increases the activity of that particular pathway

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52
Q

What is mass action effect?

A

the influence of substrate availability in the rate of metabolism

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53
Q

What is catabolism?

A

enzymes speeding up the breakdown of chemical compounds

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54
Q

How do enzymes speed up reactions?

A

by lowering the activation energy required to begin the chemical reaction

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55
Q

Most enzymes end with what suffix?

A

-ase

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56
Q

What enzyme breaks down ATP and releases stored energy?

A

ATPase

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57
Q

Each step in a biochemical pathway requires what?

A

to be catalyzed by a specific enzyme

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58
Q

What happens when there is an increase in enzyme activity?

A

an increased rate of product through a metabolic pathway

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59
Q

What is a rate limiting enzyme?

A

an enzyme in a metabolic pathway in control of the reaction’s overall rate

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60
Q

What is the activity of a rate limiting enzyme determined by?

A

the accumulation of substances further down the pathway that decrease enzyme activity through negative feedback

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61
Q

Negative feedback is like what for ATP?

A

it’s like a thermostat. it either kicks on or kicks off ATP

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62
Q

What is the immediately available source of energy for almost all bodily functions?

A

ATP

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63
Q

What is an ATP molecules composed of?

A

adenosine and 3 inorganic phospate (Pi) groups

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64
Q

How is ATP broken down to release energy?

A

an ATP molecules is combined with water and acted on by the enzyme ATPase then the last phosphate group splits away, rapidly releasing free energy

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65
Q

What is phosphorylation?

A

when a phosphate group (Pi) is added to a low energy ADP to generate ATP

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66
Q

What is substrate-level phosphorylation?

A

when ATP is generated without oxygen availability

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67
Q

What is oxidative phosphorylation?

A

when ATP is generated with oxygen

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68
Q

How much ATP can cells store?

A

only limited amounts of ATP because it must constantly generate new ATP to provide energy

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69
Q

What three metabolic pathways do cells use to generate ATP?

A

the ATP-PCr system, the glycolytic system, and the oxidative system

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70
Q

What metabolic pathway systems are anaerobic?

A

the ATP-PCr system and glycolytic system

71
Q

What metabolic pathway system is aerobic?

A

the oxidative system

72
Q

What muscle fibers use the ATP-PCr system?

A

type 2a/2b

73
Q

What is the ATP-PCr’s energy system?

A

phosphocreatine (PCr)

74
Q

What substrate does the glycolytic system use?

A

carbohydrates

75
Q

What substrate does the oxidative system use?

A

carbs and fats

76
Q

What is phosphocreatine?

A

a high energy molecule that stores energy

77
Q

How does PCr help create energy?

A

phosphocreatine (PCr) donates a phosphate (Pi) group to ADP to form ATP

78
Q

Energy released by the breakdown of PCr does what to ATP?

A

it regenerates ATP to maintain a constant supply under resting conditions

79
Q

What enzyme catalyzes PCr to release energy?

A

creatine kinase (CK)

80
Q

What happens to CK when ATP levels are down?

A

CK activity is up

81
Q

What happens to CK when ATP levels are high?

A

CK activity is down

82
Q

What happens to CK when exercise progresses and ATP is being generated by the other two systems?

A

CK activity is inhibited

83
Q

What is the ATP-PCr system classified as?

A

substrate-level metabolism

84
Q

What is the ATP yield in the ATP-PCr system?

A

1 mol ATP/1 mol PCr

85
Q

What is the duration of the ATP-PCr system?

A

3-15 sec

86
Q

What happens at exhaustion of the ATP-PCr system?

A

both ATP and PCr levels are low and unable to provide energy for further muscle contraction and relaxation

87
Q

What does the glycolytic system use as its substrate?

A

glucose or glycogen

88
Q

Why is the glycolytic system glycolytic?

A

it entails glycolysis

89
Q

What is glycolysis?

A

the breakdown of glucose through a pathway that involves a sequence of glycotic enzymes

90
Q

How is ATP produced in the glycolytic system?

A

the system involves the liberation of energy through the breakdown of glucose

91
Q

Where does blood glucose come from?

A

from the digestion of carbs and breakdown of liver glycogen

92
Q

What is glycogenesis?

A

when glycogen is synthesized from glucose and stored in the liver or muscle until needed

93
Q

What is glycogenolysis?

A

when glycogen is broken down to glucose-1-phosphate and enters a glycolysis pathway

94
Q

When can glucose or glycogen be used to generate energy?

A

after it’s been converted to glucose-6-phosphate

95
Q

How long does the glycolytic system last?

A

15 seconds to 2 minutes

96
Q

When does glycolysis begin?

A

when glucose-6-phosphate is formed

97
Q

What does glycolysis require to breakdown glycogen?

A

10-12 enzymatic reactions for the breakdown of glycogen to pyruvic acid, which is then turned to lactic acid

98
Q

Where does glycolysis take place?

A

the cell cytoplasm

99
Q

What is the net gain from glycolysis if glycogen is used?

A

3 mol of ATP for each mole of glycogen broken down

100
Q

What is the net gain from glycolysis if glucose is used?

A

2 mol of ATP for each mole of glucose broken down

101
Q

Why is the net gain different if glucose is used?

A

1 mol of ATP was used to convert glucose to glucose-6-phosphate

102
Q

Does the glycolytic system produce large amounts of ATP?

A

no

103
Q

What is a limitation to the glycolytic system?

A

it causes an accumulation of lactic acid in the muscles and body fluids

104
Q

How does the glycolytic produce lactic acid?

A

glycolysis produces pyruvic acid and without oxygen, the pyruvic acid is converted to lactic acid

105
Q

In all-out sprints, how much can lactic acid increase in the glycolytic system?

A

it can increase from a resting value of 1 mmol/kg to more than 25 mmol/kg

106
Q

What is the rate-limiting enzyme in the glycolytic pathway?

A

Phosphofructokinase (PFK)

107
Q

What happens to PFK activity when ATP is low?

A

it increases and speeds up glycolysis

108
Q

What happens to PFK activity when ATP activity is high?

A

it decreases and slows down glycolysis

109
Q

What feeds back to inhibit PFK in glycotic pathways?

A

products of the Krebs cycle

110
Q

What system produces low ATP?

A

ATP-PCr system

111
Q

What system produces moderate ATP?

A

glycolytic system

112
Q

What system produces the most ATP?

A

oxidative system

113
Q

How does the oxidative system generate energy?

A

by the body breaking down substrates with the aid of oxygen … AKA cellular respiration

114
Q

Where does the oxidative production of ATP occur?

A

in the mitochondria

115
Q

What system is the most complex out of the three bioenergetic systems?

A

the oxidative system which is why it takes the longest

116
Q

What substrate does oxidative energy production come from?

A

carbohydrates (starting with glycolysis) or fats

117
Q

What 3 stages are involved in oxidative production of ATP from carbohydrates?

A

stage 1: glycolysis, stage 2: the kreb’s cycle, stage 3: the electron transport chain

118
Q

In the presence of oxygen during glycolysis, what is pyruvic acid converted into?

A

acetyl coenzyme A (acetyl CoA)

119
Q

What does the presence of oxygen determine in glycolysis?

A

the end fate of pyruvic acid

120
Q

What is the ATP yield of glycolysis in the oxidation of carbohydrates?

A

the same ATP yield as anaerobic glycolysis whether its glycogen or glucose

121
Q

How does glycolysis in the oxidation of carbohydrates differ from anaerobic glycolysis?

A

in the presence of oxygen, the pyruvic acid goes to the kreb’s cycle

122
Q

How does the pyruvic acid get to the kreb’s cycle in glycolysis?

A

the pyruvic acid converts to acetyl-CoA then enters the kreb’s cycle

123
Q

What is the Kreb’s cycle?

A

a series of chemical reactions that permit the complete oxidation of acetyl-CoA

124
Q

How many molecules of pyruvate are formed for every glucose molecule in the kreb’s cycle?

A

2 molecules of pyruvate

125
Q

In the presence of oxygen, each glucose molecule results in how many complete kreb’s cycles?

A

2 complete kreb’s cycles

126
Q

What is guanosine triphosphate (GTP)?

A

a high energy compound similar to ATP

127
Q

How is guanosine triphosphate (GTP) generated in the Kreb’s cycle?

A

the conversion of succinyl CoA to succinate in the Kreb’s cycle generates GTP

128
Q

How does GTP form ATP?

A

GTP transfers a phosphate group (Pi) to ADP to form ATP

129
Q

What are the results at the end of the Kreb’s cycle?

A

2 additional moles of ATP are formed and the carbohydrate is broken down into carbon dioxide and hydrogen

130
Q

What happens when too many hydrogen ions are in the cell?

A

the cell becomes too acidic

131
Q

What happens to the hydrogen ions released during the Kreb’s cycle?

A

they’re moved to the electron transport chain

132
Q

How is NAD and FAD produced in the Kreb’s cycle?

A

1 pyruvate contains 3 NAD and 1 FAD per cycle

133
Q

What is created at the end of a Kreb’s cycle?

A

3 NADs, 1 FAD and 1 ATP is created each cycle

134
Q

What carries hydrogen atoms to the electron transport chain?

A

NADH and FADH

135
Q

What chain does hydrogen travel down in the electron transport chain?

A

a proton pump, ATP synthase, then concentration gradients

136
Q

What happens as hydrogen ions move down the concentration gradient?

A

energy is transferred to ADP and ATP is formed through ATP synthase

137
Q

How many molecules of ATP are formed for every pair of electrons brought to the transport chain by NADH?

A

2.5 molecules of ATP per NADH

138
Q

How many molecules of ATP are formed for every pair of electrons brought to the transport chain by FADH?

A

1.5 molecules of ATP per FADH

139
Q

How many molecules of ATP can complete oxidation of glucose generate?

A

32 molecules of ATP

140
Q

How many molecules of ATP can complete oxidation of glycogen generate?

A

33 molecules of ATP

141
Q

What are triglycerides?

A

a major fat energy source

142
Q

Where are triglycerides stored?

A

in fat cells and between/within skeletal muscle fibers

143
Q

What has to happen to a triglyceride before it’s used for energy?

A

it has to broken down to one molecule of glycerol and 3 free fatty acid (FFA) molecules

144
Q

What is lipolysis?

A

the break down of triglycerides

145
Q

What is the primary energy source for fat metabolism?

A

free fatty acids (FFA)

146
Q

What does the rate of FFA entry depend on?

A

concentration gradient

147
Q

Fats yield how much more ATP than glucose?

A

3 to 4 times more ATP

148
Q

What is beta-oxidation (B-oxidation) of fats?

A

the process of converting FFAs to acetyl-CoA

149
Q

How many acetyl-CoA enzymes are yield by 16-carbon FFA?

A

8 acetyl-CoA enzymes

150
Q

What is needed to activate B-oxidation?

A

an input energy of 2 ATPs

151
Q

How much ATP is produced by fats?

A

it depends on the specific fat oxidized

152
Q

What regulates the kreb’s cycle?

A

negative feedback

153
Q

What is the rate limiting enzyme in the kreb’s cycle?

A

isocitrate dehydrogenase

154
Q

What does isocitrate dehydrogenase do?

A

regulates the electron transport chain

155
Q

In what circumstance is protein used for energy?

A

starvation

156
Q

What can protein be converted to?

A

glucose through gluconeogenesis or pyruvate/acetyl-CoA

157
Q

Why is protein’s energy yield hard to determine?

A

protein contains nitrogen and some nitrogen can’t be oxidized in the body

158
Q

What are 3 reasons why lactic acid is not bad?

A

it stays local, lactate shuttle, and the cori cycle

159
Q

What can happen to lactate produced in the cytoplasm?

A

it can be taken up by the mitochondria within the same fiber and be oxidized

160
Q

What is lactate shuttle?

A

transporting lactate away from its site of production and using it elsewhere

161
Q

What is the cori cycle for lactate?

A

when lactic acid is transported by blood to the liver and turned into pyruvic acid then glucose and transported back to the working muscle

162
Q

When a person exercises at the highest intensity possible, what are the 3 energy systems doing?

A

each of the systems contribute to the total energy needs of the body

163
Q

What is the crossover point?

A

the intensity where fat and carbohydrate use intersects

164
Q

What is the crossover point affected by?

A

exercise intensity and endurance training status

165
Q

What is a benefit of life long endurance training?

A

increased capacity for fat oxidation to produce ATP during exercise

166
Q

What determines oxidative capacity?

A

a muscle’s fiber type composition

167
Q

Type 2 muscle fibers are better suited for what type of energy production?

A

glycolytic

168
Q

What does endurance training do for type 2 muscle fibers?

A

it enhances their oxidative capacity

169
Q

Why should people with large percentages of type 2 fibers do endurance training too?

A

it can increase their muscles’ aerobic capacities

170
Q

What does oxidative metabolism depend on?

A

adequate supply of oxygen

171
Q

As exercise intensity increases, what does energy demands do?

A

energy demands increase

172
Q

What is the function of brown adipose tissue?

A

to transfer energy from food directly to heat and increase metabolism

173
Q

What is the uncoupling protein in brown fat?

A

it uncouples the electron transport chain from the creation of ATP

Exercise Physiology (6 decks)

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