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Applied physiology > Bioenergetics > Flashcards

Bioenergetics Flashcards

1
Q

Bioenergetics definition

A

flow and change of energy within a living system

conversion of fats,proteins,carbs into usable energy for cell work
chemical –> mechanical

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2
Q

Cell membrane

A

semi-permeable membrane that seperates the cells from extracellular environ
sarcolemma in skeletal muscle

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3
Q

Nucleus

A

contains genes that regulate protein synthesis

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4
Q

Cytoplasm

A

fluid portion of cell
contains organelles

sarcoplasm in muscle

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5
Q

Mitochondria

A

location of oxidative phosphorylation

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6
Q

Metabolism

A

sum of all chemical reactions in the body

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7
Q

Anabolic reactions

A

synthesis of molecules

example - glucose being stored as glycogen

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8
Q

Catabolic reactions

A

breakdown of molecules

example - glycogen being broken down into glucose

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9
Q

1st law of thermodynamics

A

energy cannot be created or destroyed only transformed from one form to another

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10
Q

Endergonic

A

requires energy to be added to reactants

reactants to products
e.g., glycogen formation

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11
Q

Exergonic

A

releases energy

products to reactants
e.g., ATP hydrolysis

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12
Q

Coupled reactions

A

liberation of energy in an exergonic reaction that drives an endergonic reaction

oxidation-reduction reactions

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13
Q

Oxidation

A

removing an electron

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14
Q

Reduction

A

addition of an electron

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15
Q

Carrier molecules in ETC

A

NAD
FAD

transfer hydrogen atoms with their electrons

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16
Q

Benefit of endurance exercise?

A

below VO2max
allows time to mobilize substrates from energy stores

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17
Q

Aerobic ATP production

A

ATP generation dominates and results from cooperation between citric acid cycle (krebs cycle)

completes oxidation of acetyl CoA to provide electrons

energy obtained from ETC is used to produce ATP at end

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18
Q

Citric acid cycle

A
  1. glycolysis generates 2 molecules of pyruvate
  2. pyruvate oxidised by NAD+ = NADH + H+
  3. enters the mitochondria
  4. pyruvate converted to acetyl-CoA = lose a carbon = generate CO2
  5. acetyl-CoA combines with oxaloacetate to form citrate
  6. series of reactions to regenerate oxaloacetate = generate 2 CO

= 1 ATP molecule synthesized from GTP with release of 3NADH and 1FADH2

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19
Q

Electron transport chain

A
  1. NADH and FAD re-oxidized = release high-energy electron from hydrogen atoms
    passed down a series of cytochromes coupled with the pumping of H+ into intermembrane space
  2. increase conc of H+ ions in intermembrane space
  3. movement of H+ through ATP synthase produces ATP
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20
Q

end of ETC

A

oxygen is the last electron acceptor
O2 accepts electrons passed along combines with hydrogen
= form H2O

without O2 available to accept electrons = oxidative phosphorylation not possible

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21
Q

Aerobic ATP tally per glucose molecule

A

38

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22
Q

Substrate-level phosphorylation products

A

4 ATP
10 NADH
2 FADH

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23
Q

Total ATP is variable because

A

NADH used as reducing agent
proton gradient used in transporting other substances through inner membrane into matrix

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24
Q

Enzyme

A

protein that lower the energy of activation and accelerate chemical reactions

increase rate of production formation

not consumed or changed by the reaction involved in

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25
Q

How enzymes lower the energy of activation

A

activation site and enzyme molecule

enzyme-substrate complex

product molecule
unaltered enzyme molecule

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26
Q

Kinase

A

add a phosphate group

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27
Q

Dehydrogenase

A

remove hydrogen atoms

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28
Q

Oxidase

A

catalyze oxidative-reduction reactions involving oxygen

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29
Q

pH influences enzyme activity

A

heavy exercise increase lactate threshold

increase H+ resulting in decrease pH

decrease ATP production and muscular fatigue

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30
Q

temp influences enzyme activity

A

normal body temp = 37

during exercise = 40

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31
Q

Adenosine triphosphate (ATP)

A

high-energy phosphate molecule

synthesis ADP + Pi —> ATP
breakdown ATP — (ATpase) —> ADP + Pi + energy

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32
Q

Anaerobic pathways

A

no oxygen
phosphocreatine (PC) beakdown
glycolysis

33
Q

Aerobic pathways

A

require oxygen
oxidative phosphorylation
depend on respiratory/cardiovasculary systems to deliver O2

34
Q

ATP-PC system

A

PC + ADP — creatine kinase —> ATP + C

most rapid
simplest one-enzyme reaction
~10-15s

35
Q

Glycolysis

A

ATP
2NADH
2 pyruvate or lactate

~30-90s

36
Q

Net gain if glucose substrate

A

2 ATP

37
Q

Net gain if glycogen substrate

A

3 ATP

38
Q

How is glyogen phosphorlyzed?

A

inorganic phosphate

= 3 ATP

39
Q

Energy requirements at rest

A

almost 100% of ATP produced by aerobic metabolism
blood lactate levels are low (<1.0 mmol/l)
resting O2 consumption = 0.25 l/min

40
Q

Rest to exercise transition

A

ATP production increases immediately - initial anaerobic ATP-PC –> glycolysis = oxygen deficit
oxygen uptake rapidly increases
reach steady state 1-4 mins = aerobic

41
Q

Why do endurance trained individuals have a lower O2 deficit than untrained?

A

better developed aerobic bioenergetic capacity

greater regional blood flow to active muscles (more capillaries)
increased cellular adaptation and efficiency
increased mitochondrial volume in muscle fibres = less lactate production at beginning

42
Q

Recovery from exercise

A

oxygen uptake remains elevated
EPOC - 20% elevated O2 consumption used to repay O2 deficit

43
Q

What is magnitude and duration of EPOC influenced by?

A

intenisty of exercise

44
Q

EPOC

A

excess post oxygen consumption

45
Q

Fast component EPOC

A

re-synthesis of stored PC in muscle (recovered in 60-120s)
replenishing muscle (myoglobin) and blood (haemoglobin) O2 stores

46
Q

Slow component EPOC

A

elevated HR and breathing increase O2 demand
elevated blood temp = increase metabolic rate
elevated levels of epinephrine and norepinephrine = increase metabolic rate
conversion of lactic acid to glucose (gluconeogenesis)

47
Q

Short-term high intensity exercise (<5s)

A

ATP produced via ATP-PC system

48
Q

Intense exercise >5s

A

shift ATP production via glycolysis

49
Q

Events lasting >45s

A

ATP production through ATP-PC, glycolysis and aerobic systems
50% anaerobic/50% aerobic at 2 mins

50
Q

Prolonged exercise (>10 min)

A

Aerobic metabolism to produce ATP

51
Q

Gluconeogensis

A

making of glucose from other substrates such as amino acids, lactic acid and oxaloacetate

52
Q

resting O2 consumption

A

0.25 l/min
3.5 ml/kg/min

53
Q

Glycolysis net effect

A

glucose catabolized
= 2 pyruvate
2 NADH
2 ATP

54
Q

Glycolysis process

A
  1. convert glucose to glucose 6-phospahte
  2. into fructose 1,6 - bisphosphate = 2 ATP consumed
  3. = 4 ATP molecules + 2 NADH
55
Q

Where is pyruvate oxidised?

A

mitochondria

56
Q

Where is pyruvate converted to acetyl-CoA?

A

matrix
carrier protein (pyruvate translocase) transports
coupled to H+

57
Q

Pyruvate oxidised by NAD+ =

A

NADH
H+

= Acetyle-CoA
CO2

58
Q

What limits the activity of Krebs cycle?

A

availability oxaloacetate
acetyl-CoA accumulates = converted to acetoacetate (ketone)

59
Q

Which complexes transport H+ ions from matrix to intermembrane space?

A

complexes I
III
IV

60
Q

Citric acid cycle converts ?

A

Acetyl-CoA to CO2 and H2O
NADH and FADH2

61
Q

Anaerobic glycolysis

A

O2 supplies insufficient
glucose –> pyruvate = lactic acid
small amount ATP

62
Q

EPOC phase 1

A

few minutes
phosphocreatine and ATP levels are restored
O2 stores on haemoglobin and on myoglobin recover

63
Q

EPOC phase 2

A

last 15 mins
increased O2 needed:
increased work of respiratory muscles - as result of hyperventilation
elevated body temp from exercise
elevated catecholamine levels continue to stimulate metabolism
gluconeogenesis

64
Q

EPOC phase 3

A

recovery of muscle tissue damaged during exercise
production new proteins

65
Q

Renin-angiotensin-aldosterone system

A

enzyme renin secreted by kidney = convert peptide angiotensinogen –> angiotensin I
angiotensin I – angiotensin-converting enzyme –> angiotensin II
activation angiotensin receptors = stimulate aldosterone = increase sodium reabsorption

66
Q

Angiotensin II

A

acts on angiotensin receptors
located in adrenal glands, kidneys, brain
most potent arteriolar vasoconstrictors + works together with K+

67
Q

Aldosterone secretion

A

regulated by need to maintain normal blood volume and blood pressure
normal plasma K+ conc

68
Q

Complex I

A

NADH delivered
NADH dehydrogenase
inner mitochondrial membrane
H+ ions pumped from matrix to membrane space

69
Q

Complex II

A

FADH2 deliver electrons
no H+ pump
= less ATP generated

70
Q

Complex III and IV

A

H+ pump
electrons pass to oxygen = O2- react with H+ = H2O
potential difference across inner mitochondrial membrane with intermembrane space being positive relative to the matrix

71
Q

Mobile carrier molecules

A
  1. ubiquinone
  2. cytochrome C
72
Q

Electrochemical gradient

A

drives H+ back into mitochondrial matrix through enzyme ATP synthase
energy released = synthesize ATP from ADP + Pi

73
Q

What slows glycolysis?

A

high level ATP in muscle fibre
inhibit rate limiting enzyme

74
Q

What hormone is secreted by adrenal medulla?

A

epinephrine

75
Q

Mechanisms to explain lactate threshold?

A

accelerated rate of glycolysis due to epinephrine
recruitment of fast-twitch muscle fibres
reduced rate of lactate removal from the blood

76
Q

RER

A

respiratory exchange ratio
calculated by dividing the amount of carbon dioxide produced by the amount of oxygen consumed

77
Q

RER close 1.0

A

carbs main substrate

78
Q

RER 0.7

A

fats main substrate

Applied physiology (24 decks)

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