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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
How enzymes lower the energy of activation
activation site and enzyme molecule enzyme-substrate complex product molecule unaltered enzyme molecule
26
Kinase
add a phosphate group
27
Dehydrogenase
remove hydrogen atoms
28
Oxidase
catalyze oxidative-reduction reactions involving oxygen
29
pH influences enzyme activity
heavy exercise increase lactate threshold increase H+ resulting in decrease pH decrease ATP production and muscular fatigue
30
temp influences enzyme activity
normal body temp = 37 during exercise = 40
31
Adenosine triphosphate (ATP)
high-energy phosphate molecule synthesis ADP + Pi ---> ATP breakdown ATP --- (ATpase) ---> ADP + Pi + energy
32
Anaerobic pathways
no oxygen phosphocreatine (PC) beakdown glycolysis
33
Aerobic pathways
require oxygen oxidative phosphorylation depend on respiratory/cardiovasculary systems to deliver O2
34
ATP-PC system
PC + ADP --- creatine kinase ---> ATP + C most rapid simplest one-enzyme reaction ~10-15s
35
Glycolysis
ATP 2NADH 2 pyruvate or lactate ~30-90s
36
Net gain if glucose substrate
2 ATP
37
Net gain if glycogen substrate
3 ATP
38
How is glyogen phosphorlyzed?
inorganic phosphate = 3 ATP
39
Energy requirements at rest
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
Rest to exercise transition
ATP production increases immediately - initial anaerobic ATP-PC --> glycolysis = oxygen deficit oxygen uptake rapidly increases reach steady state 1-4 mins = aerobic
41
Why do endurance trained individuals have a lower O2 deficit than untrained?
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
Recovery from exercise
oxygen uptake remains elevated EPOC - 20% elevated O2 consumption used to repay O2 deficit
43
What is magnitude and duration of EPOC influenced by?
intenisty of exercise
44
EPOC
excess post oxygen consumption
45
Fast component EPOC
re-synthesis of stored PC in muscle (recovered in 60-120s) replenishing muscle (myoglobin) and blood (haemoglobin) O2 stores
46
Slow component EPOC
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
Short-term high intensity exercise (<5s)
ATP produced via ATP-PC system
48
Intense exercise >5s
shift ATP production via glycolysis
49
Events lasting >45s
ATP production through ATP-PC, glycolysis and aerobic systems 50% anaerobic/50% aerobic at 2 mins
50
Prolonged exercise (>10 min)
Aerobic metabolism to produce ATP
51
Gluconeogensis
making of glucose from other substrates such as amino acids, lactic acid and oxaloacetate
52
resting O2 consumption
0.25 l/min 3.5 ml/kg/min
53
Glycolysis net effect
glucose catabolized = 2 pyruvate 2 NADH 2 ATP
54
Glycolysis process
1. convert glucose to glucose 6-phospahte 2. into fructose 1,6 - bisphosphate = 2 ATP consumed 3. = 4 ATP molecules + 2 NADH
55
Where is pyruvate oxidised?
mitochondria
56
Where is pyruvate converted to acetyl-CoA?
matrix carrier protein (pyruvate translocase) transports coupled to H+
57
Pyruvate oxidised by NAD+ =
NADH H+ = Acetyle-CoA CO2
58
What limits the activity of Krebs cycle?
availability oxaloacetate acetyl-CoA accumulates = converted to acetoacetate (ketone)
59
Which complexes transport H+ ions from matrix to intermembrane space?
complexes I III IV
60
Citric acid cycle converts ?
Acetyl-CoA to CO2 and H2O NADH and FADH2
61
Anaerobic glycolysis
O2 supplies insufficient glucose --> pyruvate = lactic acid small amount ATP
62
EPOC phase 1
few minutes phosphocreatine and ATP levels are restored O2 stores on haemoglobin and on myoglobin recover
63
EPOC phase 2
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
EPOC phase 3
recovery of muscle tissue damaged during exercise production new proteins
65
Renin-angiotensin-aldosterone system
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
Angiotensin II
acts on angiotensin receptors located in adrenal glands, kidneys, brain most potent arteriolar vasoconstrictors + works together with K+
67
Aldosterone secretion
regulated by need to maintain normal blood volume and blood pressure normal plasma K+ conc
68
Complex I
NADH delivered NADH dehydrogenase inner mitochondrial membrane H+ ions pumped from matrix to membrane space
69
Complex II
FADH2 deliver electrons no H+ pump = less ATP generated
70
Complex III and IV
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
Mobile carrier molecules
1. ubiquinone 2. cytochrome C
72
Electrochemical gradient
drives H+ back into mitochondrial matrix through enzyme ATP synthase energy released = synthesize ATP from ADP + Pi
73
What slows glycolysis?
high level ATP in muscle fibre inhibit rate limiting enzyme
74
What hormone is secreted by adrenal medulla?
epinephrine
75
Mechanisms to explain lactate threshold?
accelerated rate of glycolysis due to epinephrine recruitment of fast-twitch muscle fibres reduced rate of lactate removal from the blood
76
RER
respiratory exchange ratio calculated by dividing the amount of carbon dioxide produced by the amount of oxygen consumed
77
RER close 1.0
carbs main substrate
78
RER 0.7
fats main substrate

Applied physiology (24 decks)

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