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Exercise Physiology and Pharmacology > Bioenergetics and Metabolism > Flashcards

Bioenergetics and Metabolism Flashcards

1
Q

What are the three ATP pathways?

A
  1. ATP-phosphocreatine system
  2. Glycolytic system
  3. Oxidative system
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2
Q

What methods of ATP production are anaerobic?

A

ATP-phosphocreatine system and the glycolytic system.

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3
Q

What methods of ATP production are aerobic?

A

Oxidative system

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4
Q

How much energy does ATP hydrolysis produce?

A

-31 kj/mol of free energy (a negative G means that the reaction is spontaneous).

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5
Q

Is ATP a long-term energy store?

A

No, the body must constantly synthesize new ATP.

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6
Q

Explain the ATP-phosphocreatine system.

A

There is the transfer of a high-energy phosphate from creatine phosphate to ADP to regenerate ATP.

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7
Q

When is the ATP-phosphocreatine system at play?

A

During rest, so that ATP stores can be replenished to be used up during exercise.

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8
Q

What can phosphocreatine not be used for?

A

Its energy can’t be used for cellular work.

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9
Q

What can phosphocreatine be used for?

A

Its energy can be used to reassemble ATP.

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10
Q

What enzyme is used in the ATP-phosphocreatine system?

A

Creatine kinase.

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11
Q

What are the reactants in the ATP-phosphocreatine system?

A

Phosphocreatine and ADP

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12
Q

What are the products in the ATP-phosphocreatine system?

A

Creatine and ATP

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13
Q

Can the ATP-phosphocreatine system be interchangeable?

A

Yes it can.

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14
Q

How many molecules of ATP are consumed in the preparation phase in glycolysis?

A

2 molecules

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15
Q

What is the preparation phase of glycolysis?

A

Glucose is trapped in the cell and forms a compound that is readily converted into 3C molecules (DHAP and GAP).

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16
Q

How many ATP molecules are produced in the payoff phase of glycolysis?

A

4 ATP produced

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17
Q

How many NADH molecules are produced in the payoff phase of glycolysis?

A

2 NADH produced

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18
Q

What is the total amount of ATP produced in glycolysis?

A

2 ATP, since 2 are used up in the preparation phase.

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19
Q

What is the payoff phase of glycolysis?

A

The harvesting of some of the free energy of the intermediates (ATP and NADH) to produce pyruvate.

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20
Q

When is anaerobic glycolysis used?

A

When the supply of oxygen is inadequate.

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21
Q

How does anaerobic glycolysis work?

A
  1. Pyruvate molecules are turned into lactate using lactate dehydrogenase
  2. NADH is converted into NAD
  3. The NAD produced can then be used in the preparation and payoff phase of glycolysis to produce ATP
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22
Q

How do lactic acid production allow ATP production?

A

NAD is regenerated, which acts in glycolysis.

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23
Q

How much ATP does CAC produce?

A

2 ATP for both pyruvate.

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24
Q

How is ATP produced in oxidative phosphorylation (ETC)?

A

The proton gradient force formed through NADH and FAH2 oxidation allow for the activity of ATP-synthase.

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25
Q

Where does the CAC and ETC occur?

A

In the mitochondria.

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26
Q

Where does CAC occur in the mitochondria?

A

In the matrix.

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27
Q

Where does ETC occur in the mitochondria?

A

Along the inner mitochondrial membrane.

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28
Q

What are sources of energy in the body?

A

Carbohydrates, fats, and proteins (first two are most important).

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29
Q

What is glycogen synthesis?

A

Glyocogenesis

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30
Q

What is the key enzyme in glycogenesis?

A

Glycogen synthase

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31
Q

What is glycogen breakdown?

A

Glycogenolysis

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32
Q

What is the key enzyme of glycogenolysis?

A

Glycogen phosphorylase

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33
Q

What is the purpose of glycogenesis?

A

To store excess glucose in the cell for a later use. It’s stored as glycogen.

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34
Q

When does glycogenolysis occur?

A

When the body needs energy, such as during exercise. Typically it prefers glucose due to its huge ATP production.

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35
Q

What is the purpose of fat (triacylglycerol) metabolism?

A

The oxidation of fatty acids to generate energy.

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36
Q

What components make up fats?

A

Three fatty acid tails and glycerol.

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37
Q

Where is fat stored?

A

In adipose cells or tissue.

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38
Q

What does insulin promote in fat metabolism?

A

Promotes storage of triacylglycerol.

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39
Q

What does glucagon and adrenaline promote in fat metabolism?

A

Promotes lipolysis.

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40
Q

What is lipolysis?

A

When TAGs are broken down into their components, glycerol and fatty acids, and can be used to make energy.

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41
Q

How is glycerol used to make energy?

A

Can enter the liver cell to aid in glycolysis which makes pyruvate and gluconeogenesis to make glucose.

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42
Q

How are fatty acids used to make energy?

A

In other tissues, fatty acids undergo oxidation to enter as acetyl CoA in the CAC.

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43
Q

Where is glucose absorbed?

A

At the intestine.

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44
Q

What pathways are activated for ATP production during a short sprint?

A

ATP-phosphocreatine system and anaerobic glycolysis (lactate production).

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45
Q

What pathways are activated for ATP production during a long distance run?

A

ATP-phosphocreatine system and aerobic metabolism (oxidative phosphorylation; ETC).

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46
Q

What molecules are used during a short sprint to produce ATP?

A

PCr and carbohydrate.

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47
Q

What molecules are used during a long distance run to produce ATP?

A

Carbohydrates and lipids (most important).

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48
Q

Does fat metabolism require oxygen?

A

Yes

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49
Q

How does ATP-PCr compare to other systems in terms of energy production?

A

They make the most ATP/second, with 10 molecules formed.

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50
Q

Why does ATP-PCr have low available capacity?

A

Less than 15 seconds because only 1 ATP can be formed per molecule of the substrate.

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51
Q

Why does fat metabolism have the greatest available capacity for ATP production?

A

Fat metabolism can last days because less than around 100 ATP molecules can be made per molecule of the substrate (does take longer, but it more sustainable).

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52
Q

What system provides instant energy?

A

ATP-PCr

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53
Q

What system favours short-term energy?

A

Anaerobic respiration (glycolysis).

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54
Q

What system favours long-term energy?

A

Aerobic respiration (oxidative phosphorylation and fatty acid metabolism). There is a shift to fatty acid oxidation as the main fuel source when the exercise is prolonged.

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55
Q

How does the oxidative capacity (the ability to use oxygen) of muscle differ?

A

Depends on the activity of the oxidative enzymes.

56
Q

What enzyme increases oxidative capacity in muscle?

A

Succinate dehydrogenase.

57
Q

How do type 1 fibers produce ATP during exercise?

A

They need O2 to produce ATP, thus they have an aerobic metabolism.

58
Q

How do type II fibers produce ATP during exercise?

A

They produce ATP anaerobically.

59
Q

How does fatigue compare in type I and II fibers?

A

Type I fibers can maintain exercise for prolonged periods whereas type II fibers fatigue quickly.

60
Q

What are the energy demands of skeletal muscle when at rest?

A

Low

61
Q

What fuels are used for the energy demands of skeletal muscle?

A

Glucose, amino acids, and/or fatty acids.

62
Q

What is the fed state?

A

Occurs after a meal when your body is digesting the food and absorbing the nutrients.

63
Q

How is excess glucose stored in skeletal muscle?

A

As glycogen.

64
Q

What is the predominant hormone that influences skeletal muscle?

A

Insulin

65
Q

Explain the regulation of insulin release at rest.

A
  1. Glucose entry into GLUT2 of pancreatic-beta cells (when glucose in the blood is high)
  2. Intracellular ATP concentrations rise due to increase in metabolic pathways (glycolysis)
  3. This inhibits ATP-gated potassium channels, therefore no hyperpolarization of the cell and just depolarization of the membrane
  4. Influx of calcium through voltage-gated calcium channels
  5. This increases cytosolic calcium concentrations, which triggers insulin secretion via secretory vesicles
66
Q

Where does GLUT2 exist?

A

In pancreatic beta-cells.

67
Q

Where is GLUT4 expressed?

A

Adipose tissue and skeletal muscle.

68
Q

What does the expression of insulin promote?

A

The surface expression of GLUT4 transporters.

69
Q

What does an increase in surface expression of GLUT4 transporters do?

A

Increase the influx of glucose into the muscle cell for energy use.

70
Q

How does insulin promote surface expression of GLUT4 transporters?

A
  1. Insulin binds to insulin receptors on the muscle cell
  2. IRS1 (autophosphorylation) is a signaling protein that activates PI3K, a kinase that turns PIP2 to PIP3
  3. PIP3 activates Akt (kinase)
  4. Results in a downward cascade in the translocation of GLUT4 from the cytosol to plasma membrane of muscle cells
71
Q

What pathway does insulin promote?

A

Glycogenesis, thus the activation of glycogen synthase for the production of glycogen.

72
Q

What does insulin inhibit?

A

Glycogen phosphorylase to slow glycogen breakdown.

73
Q

What inhibits glycolysis?

A

High ATP concentrations.

74
Q

What does ATP inhibit in glycolysis?

A

PFK, which is the committed step in glycolysis and pyruvate kinase.

75
Q

What does the stimulation of the anterior pituitary gland during exercise produce?

A

Growth hormone

76
Q

What does the growth hormone do?

A

It provides an anabolic effect to promote protein synthesis to help aid in repair and muscle growth.

77
Q

What does the stimulation of the thyroid gland during exercise produce?

A

Thyroxine

78
Q

What does thyroxine do?

A

Increases the basal metabolic rate, which is understood during exercise because of the increased metabolic demands of muscle.

79
Q

What is the basal metabolic rate?

A

The amount of energy (calories) your body needs to maintain homeostasis.

80
Q

What does the stimulation of the adrenal gland during exercise produce?

A

Adrenaline and noradrenaline

81
Q

What do adrenaline and noradrenaline do?

A

They increase glycogenolysis and lipolysis (breakdown of glycogen and fats to provide energy) in the skeletal muscle.

82
Q

What does the stimulation of the pancreas during exercise produce?

A

Insulin and glucagon.

83
Q

What does glucagon do?

A

It increases glycogenolysis and lipolysis (breakdown of glycogen and fats to provide energy).

84
Q

Where does the regulation of glucagon release occur?

A

Pancreatic alpha-cells.

85
Q

How is glucagon release regulated in low concentrations of glucose?

A
  1. Voltage-gated sodium and calcium channels are open to fire action potentials (depolarization of the cell)
  2. There is an influx of calcium to stimulate glucagon secretion
86
Q

How is glucagon release regulated in high concentrations of glucose?

A
  1. Sodium channel inactivation prevents calcium influx and glucagon secretion
  2. This is linked to ATP-gated potassium channel inactivation
87
Q

Where are carbohydrates used during exercise for metabolism?

A

During glycolysis and oxidative phosphorylation.

88
Q

What negative feedback occurs in glycolysis when at rest?

A

Increase in glucose 6-phosphate from glycogenesis inhibits hexokinase, which is the first enzyme in glucose.

89
Q

What feedforward stimulation occurs in glycolysis during exercise?

A

Production of fructose 1,6-bisphosphate stimulates the activity of pyruvate kinase.

90
Q

Where does glycogenolysis occur?

A

In the muscle and the liver.

91
Q

What is the product of glycogenolysis?

A

Glucose 6-phosphate, the second intermediate in glycolysis.

92
Q

What is the reactant of glycogenolysis?

A

Glycogen

93
Q

Where does gluconeogenesis occur?

A

The liver

94
Q

What are the reactants of gluconeogenesis?

A

Lacate, glycerol, and amino acids.

95
Q

What is the product of gluconeogenesis?

A

Glucose

96
Q

What hormones stimulate glycogenolysis and gluconeogenesis?

A

An increase in glucagon and adrenaline, and a decrease in insulin.

97
Q

What are drivers for insulin-independent glucose uptake?

A

AMP and calcium.

98
Q

What are the key regulatory enzymes in insulin-independent glucose uptake?

A
  1. Calmodulin kinase (CaMK)
  2. AMP-activated protein kinase (AMPK)
99
Q

How does insulin-independent glucose uptake occur through CaMK?

A
  1. An increase in intracellular calcium in skeletal muscle via the SR
  2. Calcium binds to calmodulin which activates CaMK
  3. CaMK allows for the translocation of the GLUT4 via phosphorylation from the cytoplasm to the plasma membrane
100
Q

How does insulin-independent glucose uptake occur through AMPK?

A
  1. Glucose enters skeletal muscle through GLUT4
  2. G6P is produced in glycolysis and undergoes catabolism (breakdown)
  3. ADP released forms ATP
  4. ATP hydrolysis from the energy demands of muscle lead to a net production of ADP
  5. An increase in ADP, increases AMP
  6. AMP activates AMPK
  7. AMPK allows for the translocation of the GLUT4 via phosphorylation from the cytoplasm to the plasma membrane
101
Q

Where does lipolysis occur?

A

In adipose tissue.

102
Q

What are free fatty acids oxidized into?

A

Acetyl-CoA, plus the addition of NADH generation during the process.

103
Q

Where does fatty acid oxidation occur?

A

In the mitochondrial matrix of skeletal muscle.

104
Q

Why is there such a great amount of energy released when ATP is hydrolyzed?

A

The negative charges between phosphates creates such a great strain that when broken, a great amount of energy is released.

105
Q

Where does creatine exist?

A

It the kidneys.

106
Q

Where is PCr created and stored?

A

In skeletal muscle, specifically created in the intermembrane space of mitochondria.

107
Q

What is phosphoryl transfer potential?

A

The ability of an organic molecule (PCr) to transfer a phosphoryl group to an acceptor molecule (ADP).

108
Q

Why does PCr have a greater phosphoryl transfer potential than ATP?

A

Because the phosphate bond that is broken in PCr, releases more energy than the hydrolyzation of ATP.

109
Q

Where does creatine kinase work?

A

In the myofibrils, since its purpose it to regenerate ATP for muscle contraction.

110
Q

Does creatine kinase work one way only?

A

No, it can work in the reverse generating phosphocreatine again.

111
Q

What is substrate-level phosphorylation?

A

When a phosphoryl group is transferred from a substrate to ADP or GDP to form ATP and GTP, coupled with the release of free energy.
ex. PCr or payoff phase in glycolysis

112
Q

What is oxidative phosphorylation?

A

Electrons derived from NADH/FADH2 combine with OXYGEN, and the energy released from these oxidation/reduction reactions drive the synthesis of ATP.

113
Q

How much ATP produced from a single glucose molecule?

A

32 ATP

114
Q

What happens to the lactate is produced by lactate dehydrogenase in anaerobic glycolysis?

A

Lactate dehydrogenase converts lactate back into pyruvate in the liver (elsewhere), so that NADH concentrations remain fixed (known as the Cori Cycle).

115
Q

How does glycogen storage compare in muscle versus the liver?

A

Muscle = glycogen stores stay in the muscle to be converted to glucose to aid in muscle contractions.
Liver = the glycogen stores can leave during certain exercise types in order to maintain blood glucose levels.

116
Q

What molecule links glycogenesis/genolysis to glycolysis?

A

Glucose 6-phosphate

117
Q

How are triacylglycerols held?

A

By ester linkages through glycerol.

118
Q

Why does oxidative phosphorylation, whether carbohydrate or fatty acid, take longer than anaerobic forms?

A

Due to the longer chains they must go through (glycolysis –> CAC –> ETC).

119
Q

Why does aerobic respiration increase for long-term energy?

A

There is an increased blood supply to the muscle, thus a greater amount of oxygen is being delivered.

120
Q

Why does our oxidative capacity increase as we start training?

A

The training increase our cardiovascular potential, thus oxidative capacity. The increase in oxidative capacity is due to gene expression (more enzymes made for ETC or FAO) and more mitochondria in each cell for oxidative phosphorylation.

121
Q

What is Akt known as?

A

Protein kinase B

122
Q

Why are aerobic pathways dominate during long-term exercise?

A

Because they make the most ATP.
ex. ETC/CAC make 32 ATP per glucose molecule

123
Q

Why does free fatty acid concentrations in the blood increase during prolonged exercise?

A

This is because TAGs from adipose are broken down into free fatty acids and glycerol to provide fuel for the muscle.

124
Q

What happens to pyruvate dehydrogenase during prolonged exercise?

A

It increases but falls after 120 minutes.

125
Q

What happens to glycogen during prolonged exercise?

A

Concentrations decrease.

126
Q

What does pyruvate dehydrogenase do?

A

Convert pyruvate to acetyl CoA.

127
Q

What does the reduction in PDH activity suggest?

A

The carbohydrate metabolism isn’t important in prolonged exercise. It begins to switch over to a fatty acid aerobic metabolism.

128
Q

How do blood lactate levels in the blood change during prolonged exercise?

A

They stay the same.

129
Q

How do blood glucose levels in the blood change during prolonged exercise?

A

They stay the same

130
Q

How do blood glycerol levels in the blood change during prolonged exercise?

A

They increase

131
Q

How do plasma insulin levels in the blood change during prolonged exercise?

A

They decrease

132
Q

How do blood free fatty acid levels in the blood change during prolonged exercise?

A

They increase

133
Q

What hormone increases during exercise?

A

Glucagon and adrenaline/noradrenaline.

134
Q

What is anabolism?

A

When simple molecules are synthesized to form complex ones.

135
Q

What is catabolism?

A

The breakdown of complex molecules to simple ones.

136
Q

Is exercise an example of anabolism or catabolism?

A

Catabolism

137
Q

How does glucagon (liver) or adrenaline (muscle) stimulate glycogenolysis?

A
  1. Glucagon and adrenaline bind to a GPCR
  2. Conformational change and GTP-G alpha subunit dissociates
  3. Binds to adenylyl cyclase
  4. Increase in cAMP = PKA activation
  5. Phosphorylase kinase stimulation
  6. Phosphorylase b –> a activation, thus the activation of glycogen phosphorylase

Exercise Physiology and Pharmacology (9 decks)

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