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Sport Sci > Fuel Sources and Energy metabolism (lecture three) > Flashcards

Fuel Sources and Energy metabolism (lecture three) Flashcards

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Sports Trivia flashcards
1
Q

What is the equation of work?

A

w = f.d

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2
Q

What is the equation of energy?

A

E = w/t

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3
Q

What does energy provide?

A

The capacity to do work (mechanical work)

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4
Q

What is the first law of thermodynamics?

A

Energy is neither created nor destroyed only transfered

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5
Q

What is sports nutrition about?

A

Transferring the energy of food into work

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6
Q

What is efficiency?

A

How much energy available is transformed into work

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7
Q

Define gross efficiency:

A

Work accomplished / energy expended . 100

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8
Q

How efficient is a human?

A

20-30% efficient

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9
Q

What happens to the rest of the energy that is not converted to mechanical work?

A

The energy becomes heat energy and is convected, conducted, radiated or evaporated away from the body

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10
Q

What is economy in terms of sports science?

A

Economy takes into account the quantity of oxygen consumed.

A more adapted person e.g a runner, has physiological changes i.e skeletal reconstruction that improves their economy.

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11
Q

Define Energy Expenditure

A

EE = Energy expended per a unit time.

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12
Q

What units can EE be expressed as?

A

Kilocalories or Kilojoules

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13
Q

Whats a calorie?

A

Amount of Energy required to raise 1g of water by 1 degrees

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14
Q

Whats a joule?

A

The amount of energy required to move 1g at 1ms

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15
Q

What is the ration of cal to joules?

A

1 cal = 4.186 J

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16
Q

When quantifying energy, what magnitude do we normally use?

A

Kcal or Kj

As cal and joules are very small units

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17
Q

How is the energy of a food quantified?

A

Direct Calorimetry using a bomb calorimeter .

I.e combusting things and measuring the change in water temperature for its given weight.

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18
Q

How would you measure human calorie expenditure?

A

Indirect calorimetry

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19
Q

What are the methods for determining the contribution of nutrients to a food item.

A

Determine the calories.

cal = 4% PRO + 9%FAT + 4%CHO

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20
Q

When considering nutritional intake, what are some further considerations as to the quantity of energy needed?

A

Physiological energy estimates are overestimated b/c

  • Different fuel sources have different efficiency in use
  • Absorption across the gut varies by nutrient
  • Some food sources contain larger quantities of micro nutrients that should be considered - i.e it could give calorific value than is the case. or doesnt have 494 distribution
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21
Q

What else must be taken into consideration when determining calorific values?

A

Different carbohydrate atom arrangement produce different quantities of energy.
AS does fatty acid tail length.
Also nitrogen content of amino acids in proteins.

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22
Q

Define energy metabolism:

A

Storage forms of energy are converted to ATP

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23
Q

How long is the storage of ATP able to provide muscle contraction for?

A

2 seconds of force contraction would use all stored ATP

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24
Q

How much energy does the cleavage of phosphate from ATP produce?

A
  1. 5 KJ / mol

7. 3Kcal/mol

25
Q

Why is ATP needed?

A

Cross bridge cycle

Membrane potential - Polarity - Active transport

26
Q

What provides the stored ATP with instantaneous replenishment?

A

The PCr ATP system.

I.e PCr cleaves Pi and releases energy. The Energy then bonds Pi to ADP.

Requires Creatine Kinase.

27
Q

What is the enzyme involved in the PCr-ATP system?

A

Creatine Kinase

28
Q

What Four systems do we look at for ATP production/

A

PCr-ATP
Glycolysis
Krebs Cycle
Electron Transport Chain / Oxidative Phosphorylation

29
Q

In glycolysis, Glucose or glycogen must be converted, requiring energy. What is this cost?

A 
Glucose = 1 ATP to convert.
Glycogen = 2 ATP to convert
30
Q

What are the product of glycolysis?

A

5ATP net yeild = 3ATP
H2O
Pyruvate Converted to lactate by Lactate dehydrogenase

31
Q

The process of forming a product that can enter the krebs cycle produces what as a biproduct?

A

Hydrogen ions (acidifies the environment) and CO2

32
Q

What prevents the environment from acidfying?

A

The electron transport chain accepts Hydrogen ions from the Krebs cycle / process and produces 34ATP as a result and water.

33
Q

How many ATP does the krebs cycle produce?

A

2 ATP

34
Q

What prevents glycolysis from being a long term provider of energy apart from being inefficient?

A

Lactate formation inhibits the glycolysis cylcle

35
Q

Are carbohydrates the only thing that can enter the krebs cycle?

A

No Proteins and fats can to.

In fact fats produce a total of 129ATP (including the e transport chain)

36
Q

What are the three types of muscle fibres?

A

Type I
Type IIa
Type IIb

37
Q

What is the implication of three different muscle fibres?

A

Different mechanisms for energy production

38
Q

What are the energy mechanisms of type I fibres?

A

Type I
Slow twitch - fatigue resistant
Oxidative

39
Q

What are the energy mechanisms of Type IIa fibres?

A

Type IIa
Fast twitch - powerful
Oxidative-glycotic

40
Q

What are the energy mechanisms of type IIb fibres?

A

Type IIB
Fast Twitch - powerful
Glycotic

41
Q

How can the relative number of mitochondira in a fiber be determined?

A

Primary method of ATP production,

if oxidative then high mitochondria

42
Q

Does each muscle have the same proportion of muscle fibre types?

A

No, Each muscle has different ratio of fibres depending on action and usage

43
Q

What are the relative energy stores of a 70kg man?

A

Fat = 10500g = 378000kJ

Muscle Glyogen = 350g = 5600kJ
Liver Glycogen = 100g = 1600kJ
Blood Glycogen = 20g = 320 KJ

Protein = 9000g = 153000kJ

44
Q

What are the five methods of ATP production during exercise and the time it takes for each method to kick in?

A 
Fat Oxidation 2+ hrs
Blood Glucose Oxidation 90mins
Glycogen Oxidation 1-3mins
Glycolysis 5-10sec
PCr breakdown instantaneous
45
Q

With the five methods of ATP production, which produce the greatest quantity of ATP the fastest?

A 
Fat Oxidation Slowest
Blood Glucose Oxidation 
Glycogen Oxidation 
Glycolysis
PCr breakdown Fastest
46
Q

What is the cross over concept?

A

That over time the oxidation of carbohydrates is exceeded by that of fats (~90mins) and at this point onwards capacity to continue at that level of intensity of work starts deminish i.e you get slower

47
Q

What is the function of enzymes in energy release?

A

Enzymes control most of the energy reactions within a cell.

48
Q

What are some examples of enzyme regulation?

A

Freeing of triglycerides - hormone sensitive lipase

Breakdown of glycogen - glycogen phosphorylase

Reactions of glycolysis - Hexokinase

Reactions of the TCA Cycle - Citrate synthase

49
Q

What regulates enzyme function?

A

Temperature

Concentrations

pH

Substances that bind to enzymes e.g hormones

50
Q

Where do hormones for the regulation of metabolism normally reside?

A

They generally come from the Hypothalamus, Pituitary axis.

Therefore Hypothalamus release regulatory hormones that cause hormonal release from the pituitary and these hormones act on target organs to release further hormones…

51
Q

What are the two possible uses of metabolic hormones?.

A

Anabolism or Catabolism

52
Q

What are the Metabolic Hormones to be known for this course?

A 
Insulin
Glucagon
Growth Hormone
Cortisol
Epinephrine
Norepinephrine
53
Q

Where is insulin released from and what is its effect?

A

Released from the Beta cells from the islets of langherhan in the pancreas.

It is anabolic:

  • Inhibits lipolysis and promotes fat synthesis
  • Increases glucose uptake in muscle and liver
  • Increases amino acid uptake

The concentration of insulin falls during exercise as fuels need to be liberated not stored

54
Q

Where is glucagon released from and what is effects?

A

Released from the Alpha cells from the islets of langherhan in the pancreas.

It is Catabolic:
-Raises blood glucose by increasing glycogen
breakdown in the liver.
-Increases the making of new glucose in the liver
-Activates triglyceride breakdown

55
Q

What is the function of growth hormone and where is it released from?

A

Growth hormone is released from the Anterior pituitary.

Anabolic or Catabolic

Promotes triglyceride breakdown
Increases protein synthesis

56
Q

What is the function of cortisol and where is it released from?

A

Released from the zona fasiculus of the adrenal cortex.

Catabolic

  • Increases breakdown of protein
  • Stimulates making of new glucose
  • Stimulates breakdown of fat
57
Q

What is the function of epinephrine?

A
  • Secreted from adrenal medulla (and nerves)
  • Fight or Flight response
  • Glycogenolysis in muscle
  • Lipolysis in fat
  • Catabolic
58
Q

How does exercise manipulate energy efficiency?

A 
• In general exercise training
makes the body more adept
at interpreting signals and
reactions
• Fuel selection gets slightly
more efficient
• Need less hormone
variation to stimulate
changes
• Energy status is better
maintained

Sport Sci (20 decks)

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