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metabolic control and regulation Flashcards

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1
Q

how much energy do we get from carbohydrates, lipids & proteins?

A
  • carbs: 4kcal
  • lipids: 9kcal
  • protein 4kcal
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2
Q

basal metabolic rate (BMR (Kcal)

A

minimum amount of energy needed

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3
Q

how much energy do humans need?

A

men: 66 + (13.7xweight) + (5xHeight) - (6.8xAge)
women: 655 + (9.6xW) + (1.7xH) - (4.7xA)

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4
Q

abbreviated weir formula

A

resting energy expenditure (REE)
REE= 3.9(VO2) = 1.1(VCO2) = 1.44

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5
Q

energy balance

A
  • energy intake (calories eaten) & energy expenditure (calories burned)
  • the center of obesity and T2D
  • helps us understand energy requirements of athletes
  • need to understand how the body uses fuel
  • how to accurately measure energy intake (EI) and energy expenditure (EE)
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6
Q

when will body mass stay the same?

A

intake = expenditure

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7
Q

when will body mass increase?

A

intake > expenditure

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8
Q

when will body mass decrease?

A

intake < expenditure

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9
Q

how to measure energy expenditure?

A
  • accelerometer
  • doubly labelled water
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10
Q

doubly labelled water

A
  • best method to measure day to day expenditure
  • water labelled with 2H and/or 18O, initially applied to measure body composition
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11
Q

simplistic overview of metabolism

A
  1. consumption of food filled with energy
  2. release of energy -> breaking down sugar releases energy -> energy used by cells to perform functions
  3. digestive system -> digestive enzymes break carbohydrates into sugars (glc), fats into fatty acids and proteins into a.a
  4. enzyme meet up -> more enzymes meet & bind with compounds -> undergo chemical reactions
  5. energy store -> reactions happen to release energy for immediate or future use -> energy stored in skeletal muscles, liver or body fat
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12
Q

ATP

A
  • adenosine triphosphate
  • large amount of free energy if broken down
  • 7.3kcal of free energy
  • breaking of high energy phosphate bonds (outermost P)

ATP + H2O -> ADP + Pi + H+

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13
Q

where is ATP used?

A
  • digestion
  • circulation
  • muscle contraction
  • tissue synthesis
  • nerve conduction
  • glandular excretion
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14
Q

if we had no ATP / couldnt produce ATP

A
  • death
  • rigor mortis
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15
Q

ATP and muscle contraction

A
  1. myosin head attaches to actin myofilament -> cross bridge
  2. inorganic P generation in previous contraction cylce released -> initiates power (working) stroke -> myosin head pivots & bends -> pulls on actin filament, sliding it to M line -> ADP released
  3. new ATP attaches to myosin head -> link between myosin & actin weakens -> cross bridge detaches
  4. ATP split into ADP + Pi -> myosin head energized (cocked in high energy conformation) (by released energy)
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16
Q

why do we need ATP for muscle contraction?

A
  • need it to allow cross bridge to form
  • without cross bridge = no contraction
  • a recycling process
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17
Q

is ATP limited?

A
  • yes
  • limited supplied & high demand = ATP needs to be resynthesized (from ADP) to meet needs
  • food we eat and store provides energy to recharge ATP
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18
Q

how much ATP does our body store?

A

80-100g

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19
Q

ATP consumption at rest

A

1.6kg/hr

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20
Q

ATP usage during strenuous exercise

A
  • rise 20-30 fold
  • 0.5kg/min
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21
Q

carbohydrate metabolism

A
  • abundant
  • 40-80% of total energy
  • broken down to glc units -> taken into cells -> broken down to release energy trapped in glc
  • bonds holding glc contains ATP -> need to be broken
  • glycolysis

C6H12O6 + 6O2 -> 6CO2 + 6H2O + ATP (36)

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22
Q

how is glc stored?

A
  • as glycogen
  • muscles = largest store of glycogen
  • livers = provide brain with energy e.g. when sleeping
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23
Q

types of carbohydrates

A
  • monosaccharides (glc, fructose)
  • disaccharides (sucrose)
  • polysaccharides (starch)
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24
Q

what determines how fast muscle glycogen stores are used up?

A

exercise intensity

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25
Q

glycolysis - CHO oxidation

A
  • 4 ATP produced
  • 2 used up
  • net gain of 2 ATP
  • glc -> pyruvate
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26
Q

NAD+ & NADH

A
  • electron carries (carry H)
  • provides the cell with a mechanism for accepting and donating electrons
  • NAD+ = low energy form (accepts electrons)
  • NADH = high energy form (donates)
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27
Q

lactate formation

A
  • if anaerobic
  • use NADH from stage 5 of glycolysis -> NAD (feeds back to glycolysis)
  • pyruvate -> lactate
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28
Q

lactate formation depending on exercise intensity

A
  • light exercise has a lower ATP demand -> removal of pyruvate at same pace as production
  • moderate intensity -> lactate diffuses out of muscle fibres into blood -> as exercise proceeds: lactate levels decrease and easily removed at this intenisty with good blood flow (e.g. walking after a run)
  • heavier exercise -> lactate conc stays high and constant in muscle & blood -> can be uncomfortable
  • high intensity -> increased released of lactate in blood -> reduced muscle function
    (acidity in muscle drops)
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29
Q

lactate byproduct in anaerobic conditions

A
  • after intense exercise, the lactate produced diffuses from the muscle into the blood and is taken up by the liver to be converted into glucose and glycogen -> can be recylced
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30
Q

Krebs cycle

A
  • aerobic
  • first pyruvate -> acetyl-CoA (mitochondria fluid matrix)
  • 2 molecules of pyruvate: 2xCO2 + 4xH+
  • 2 molecules of acetyl-CoA: 4xCO2 + 16H+ -> to electron transport chain
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31
Q

electron transport chain (ETC)

A
  • ultimate e- acceptor in aerobic = O2
  • e- need special carries to be transferred from food to O2
  • use NAD+ and FAD -> NAD+ from glycolysis & krebs, FAD from krebs -> both accept a H+ and 2e- -> NADH + FADH2 -> carry e- to O2 in ETC in inner membrane of mitochondria
  • oxidative phosphorylation = ATP formation
  • 90% of ATP production
  • water also formed
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32
Q

examples of short term challenges to energy

A
  • sprints
  • explosive movements
  • lifting weights
  • need ATP immediately (40-50 fold ATP increase)
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33
Q

effect of cyanide phenylhydrazones

A

stop ATP formation in the ETC

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34
Q

phosphagen system

A
  • intramuscular store of ATP = 80-100g
  • intramuscular store of phsophocreatine (PCr) = phosphagen system
  • immediate energy store for muscles
  • function as an immediate access reserve of high energy phosphates that can be used to make ATP
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35
Q

type 1 muscle fibres

A
  • low ATPase activity (at pH 9.4)
  • slow twitch
  • have high oxidative and low glycolytic capacity
  • are relatively resistant to fatigue
  • slower released energy source
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36
Q

type 1 fibres speed

A

slow

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37
Q

type 1 fibre glycolysis

A

low

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38
Q

type 1 fibre energy store used

A

fat -> slower release

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39
Q

type 1 fibre metabolism

A

aerobic

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40
Q

type 2a fibres

A
  • intermediate fibers because they possess characteristics that are intermediate between fast fibers and slow fibers
  • produce ATP relatively quickly, more quickly than SO fibers
  • can produce relatively high amounts of tension.
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41
Q

type 2a fibres speed

A

moderately fast

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42
Q

type 2a fibres gylcolysis

A

high

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43
Q

type 2a fibres energy store

A

PCr, glycogen -> energy attained faster

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44
Q

type 2a fibres metabolism

A

long anaerobic

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45
Q

type 2x fibres

A
  • fast glycolytic fibers
  • fastest twitch speeds
  • highly fatigable
46
Q

type 2x fibres speed

A

fast

47
Q

type 2x fibres glycolysis

A

high

48
Q

type 2x fibres energy store

A

PCr, glycogen -> fast

49
Q

type 2x metabolism

A

short anaerobic

50
Q

can we train / change our muscle fibre type?

A

combine type 1 and 2a and 2x:
- using high velocity isokinetic contractions
- ballistic movements: bench press throws and sprints

from type 2 to type 1:
- longer duration, higher volume endurance events

conclusions.
- exercise induced muscle fibre shifting only exists between fast twitch muscle fibre types
- bi-directional shifting between slow and fast twitch fibres

51
Q

type 1 fibres found in which atheletes?

A
  • long duration contractile activities
  • endurance athletes
52
Q

type 2a and 2x fibres found in which atheletes?

A
  • short duration anaerobic activities
  • higher strength and power
53
Q

genetics

A
  • e.g. successful endurance athletes tend to be from eastern africa
54
Q

ATP use in high intensity exercise (in each fibre)

A
  • ATP levels drop dramatically
  • 2x: drop fastest
  • 2a: middle
  • 1: slow twitch fibres go into effect after initial energy burst -> not such an extreme drop
  • ATP needs to be resynthesised fast to maintain power output
55
Q

phosphocreatine

A
  • PCr store in muscle can be used to quickly resynthesise ATP stores in muscle depleted during exercise -> to sustain contractions
  • PCr has a higher phosphate transfer pot than ATP (transfers more readily)
  • 4x more PCr stored in muscles than ATP
  • PCr rephosphorylates the ADP back to ATP
    creatine kinase
    PCr + ADP + H+ -> ATP + Cr
56
Q

resynthesis of PCr stores

A
  • adaptations occur after repeated efforts
  • ability to e.g. sprint again depends on having ATP available again after it was used in the first sprint
  • after 30s PCr replenished by 50%
  • 2-3 mins between sets to let PCr regenerate
57
Q

creatine supplements

A
  • Cr conc in muscle = 110-120mmol/kg/dry weight of muscle
  • supplements = 130-160mmol/kg/dry weight of muscle
  • more creatine available in cytosol = more ATP able to be resynthesized
58
Q

success of creatine supplements

A
  • works best for people who do have such high resting creatine levels e.g. vegetarians
  • those who conusme e.g. more red meat have higher levels already
59
Q

effectiveness of creatine supplements

A
  • has a strength gain -> can make ppl stronger
  • can train harder for longer with a faster recovery
  • increases PCr resynthesis during recovery between high intensity exercise
  • enhanced performance
  • poor evidence for endurance
60
Q

creatine and increased body mass

A
  • body mass will increase when taking creatine bc combines with water in body -> Creatine helps increase muscle mass by drawing extra water into the muscle cells, causing you to retain fluid
  • While your muscles haven’t actually started growing yet, the increased water is important for future muscle growth, and can be the cause of initial weight gain.
61
Q

what happens when PCr runs out?

A
  • switch to anaerobic glycolysis (lactic acid system)
    gly/glycogen -> pyruvate -> lactate
  • anaerobic glyc max around 5s into high intensity exercise
  • PCr declines fast
  • PCr used in final sprints
  • anaerobic used to maintain speed in middle distance runs
  • when events get longer -> aerobic -> oxygen delivery to muscles to maintain speed
62
Q

fat as an energy source

A
  • stored fat is most abundant and provides the most energy
  • greater energy yield but needs more oxygen per molecule of fat
  • glc needs 6O2
  • fat needs 23O2
  • as you increase exercise you become more reliant on muscle glycogen and less on fat
63
Q

where and how is fat stored?

A
  • 90% stored as triglycerides
  • stored in adipose tissue
64
Q

triglyceride

A

3 fatty acids bonded to a glycerol molecule

65
Q

what happens to fat breakdown when you have a meal high in carbs?

A
  • insulin spike due to carbs -> reduced ability to break down fatty acids
  • this is due to the fact that carbs impact hormone sensitive lipase
  • once you start exercising -> insulin spike will drop and wont have such an inhibitory effect -> easier to breakdown triglycerides as energy source

-> reduces initial ability to use fats for energy

66
Q

lipase

A

an enzyme the body uses to break down fats in food so they can be absorbed in the intestines
- Lipase is produced in the pancreas, mouth, and stomach.

67
Q

why do fatty acids enter the mitochondria?

A

for β-oxidation
- need to enter the oxidative cycle

68
Q

β-oxidation

A
  • multiple steps
  • fatty acid molecules are broken down to produce energy
  • consists in breaking down long fatty acids that have been converted to acyl-CoA chains into progressively smaller fatty acyl-CoA chains
  • takes place inside mitochondria
69
Q

complete oxidation of palmitic acid

A

7xFADH2 + 7xNADH + 8xAcetyl-CoA
-> all enters the krebs cycle

70
Q

ATP yield of triglycerides with 3 palmitic acids

A

387 ATP

71
Q

16 carbon palmitic acid

A
  • saturated long-chain fatty acid with a 16-carbon backbone
  • undergoes 7 cylces of β-oxidation
72
Q

how to train your body to use more fat?

A
  • higher fat in diet
  • to help utilise it more readily when you exercise
73
Q

daily recommended energy requirements

A

2111kcal for men
1613kcal for women

74
Q

aerobic characteristics

A
  • higher capillary density
  • greater size and number of mitochondria
75
Q

metabolic responses to training

A
  • increased ability to oxidise CHO
  • increased ability to oxidise lipids
  • lower respiratory exchange ratio (RER)
76
Q

energy provision in an endurance event

A
  • most aerobically
  • gradual decline in speed over the race
  • PCr to race speed
  • anaerobic -> initial maintainance of speed & for short accelerations
  • aerobic -> burning fat and carbs -> mainly depend on this
77
Q

what if we run out of energy?

A
  • rarely in top level atheletes
  • mucle glycogen stores depleted
  • fat oxidation cant occur without CHO ox
78
Q

CHO needed for fat oxidation

A
  • oxaloacetate accepts acetly-CoA (formed from pyruvate)
  • if glycolysis not functioning (Carbs burning) -> less oxaloacetate -> cant combine to acetyl-coa
79
Q

what is a protein?

A
  • acid group/carboxyl group and amino grouo attached to a carbon atom
  • R: side chian -> structure determines a.a. characteristics
  • made of a.a. = building blocks
80
Q

peptide bonds

A
  • link a.a.
  • dipeptide = 2 a.a
  • tripeptide = 3 a.a
  • polypeptide = up to 100 a.a.
81
Q

essential a.a.

A
  • cannot be formed by body
  • need to be obtained through diet
  • 8
82
Q

non- essential a.a.

A

synthesised by body
12

83
Q

protein in diet

A
  • depends on geographical region & socio-economic & cultural factors
  • animal protein foods = 60-70% intake in developed regions
  • plant proteins = 60-80% intake in developing regions
84
Q

recommended protein intake UK

A

= 0.75g/kg body mass

85
Q

free amino acid pool

A
  • derived from dietary amino acids and the proteolysis of body proteins
  • the total amount of amino acids from the diet, protein recycling, and non-essential amino acids produced by the body that is available for metabolic processing
86
Q

amino acid synthesis in body

A
  • synthesized from intermediates in glycolysis, the citric acid cycle, or the pentose phosphate pathway.
  • in the liver?
87
Q

amino acids and krebs cycle

A
  • many a.a. needed as intermediates in kc
  • very important for energy production
88
Q

where are a.a. used in body?

A
  • brain
  • ant.pit
  • hypothalamus
  • heart
  • thyroid
  • lungs
  • liver
  • stomach
  • gallbladder
  • GI tract
  • blood
  • skin
  • muscle
  • bone
89
Q

what is protein used for?

A

15% of body mass = proteins

  • structural & mechanical e.g. muscles
  • enzymes (reactions in body)
  • hormones
  • antibodies
  • fluid balance
  • acid-base balance
  • channels and pumps
  • transport
90
Q

nitrogen balance

A
  • protein metabolism & utilisation is measured by examining nitrogen content
  • nitrogen balance: N2 intake = N2 output
    + nitrogen balance: N2 intake > N2 output (hypertrophy)
    – nitrogen balance: N2 intake < N2 output
91
Q

nitrogen balance measurement

A

N2 intake = total protein intake x 0.16
N2 output = measure all N2 excreted (urine, faeces, gas, sweat)

92
Q

factors affecting protein intake

A
  • exercise type
  • energy balance
  • gender
  • training status
  • age
93
Q

muscle hypertrophy

A
  • an increase and growth of muscle cells
  • muscles bigger due to increased protein synthesis or decreased protein degredation
    -increased muscle fibre diameter
  • need a + protein balance
94
Q

why do atheletes feel the need to take protein supplements?

A
  • muscle recovery
  • muscle hypertrophy
  • increased muscle mass
95
Q

what is ATP?

A
  • energy currency of the body
96
Q

what processes require ATP?

A
  • circulation
  • digestion
  • glandular excretion
  • muscle contraction
  • nerve conduction
  • tissue synthesis
97
Q

what macronutrient is the most abundant and economic source of food energy in the human diet?

A

carbohydrates -> 40-80% of total energy in diff pop. around world

98
Q

what is the krebs cycle?

A
  • an essential reaction cycle in the body
  • key component that underpins metabolism and is responsible for generating the body´s fuel
  • cycle derives it´s fuel from the breakdown of fats and carbohydrates
99
Q

does resistance training always cause muscle fibres to shift?

A

no

100
Q

what type of athlete would have the higher proportion of type 2x muscle fibres?

A
  • olympic weightlifters or sprinters
  • type 2x fibre tends to be involved in sports needing short periods of high intensity speed levels
  • these fibres are associated with increase / high levels of power
101
Q

What is phosphocreatine? What role does it play in energy metabolism?

A
  • PCr = substance used to create ATP when muscle ATP stores have been depeleted
  • muscle ATP stores get used up very fast -> ATP must be resynthesised for muscle contraction to be sustained -> PCr used to rephosphorylate ADP back to ATP to generate energy
  • PCr has a higher phosphate transfer potential than ATP (can transfer phosphate faster) to quickly produce energy after depletion
  • found in skeletal muscles
102
Q

how much fat is stored in adipose tissue? how are they stored?

A
  • 90%
  • stored as triglycerides (triacyglycerol) in adipose
103
Q

what does the term “hitting the wall” mean?

A
  • refers to time when body has burned up all of its glycogen stores in the muscles and the liver
  • body then turns to use fat metabolism as primary source (palmitic acid)
104
Q

problem with fat metabolism for energy

A
  • produces more energy but at a lower rate & consumes more oxygen
  • less efficient
105
Q

is a high fat meal before period of endurance exercise beneficial for performance?

A
  • no
  • carb dense diets better
106
Q

what are proteins made of? how is this diff to carbs or fats?

A
  • made from amino acids
  • amino acids have an acid group and an amino group attached to C atom
  • proteins similiar to carbs but also contain Nitrogen
  • proteins have R side chains -> determine proteins characteristics
107
Q

how many amino acids does the body require? how many are essential & non-essential?

A
  • 20 amino acids
  • 8 (9 in infants) are essential (body can´t synthesise)
  • 12 non-essentail (synthesised by body)
108
Q

what % of body mass does protein account for?

A

15%

109
Q

What important factors will you need to consider if an athlete expresses a desire to utilise protein supplements?

A
  • nutritional personalisation & balance
  • what is existing diet like? average dialy protein intake?
  • level of athlete
  • type of training
110
Q

Many of the proteins found in mitochondria are not transcribed from mitochondrial DNA. How would you best describe the pathway of such proteins from the cytoplasm into the mitochondria?

A
  • The protein is formed in the cytoplasm as a precursor protein
  • it is then transported across the two mitochondrial membranes in a single stage

human biology (11 decks)

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