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Fuel Sources and Energy metabolism (lecture three) 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
Why is ATP needed?
Cross bridge cycle Membrane potential - Polarity - Active transport
26
What provides the stored ATP with instantaneous replenishment?
The PCr ATP system. I.e PCr cleaves Pi and releases energy. The Energy then bonds Pi to ADP. Requires Creatine Kinase.
27
What is the enzyme involved in the PCr-ATP system?
Creatine Kinase
28
What Four systems do we look at for ATP production/
PCr-ATP Glycolysis Krebs Cycle Electron Transport Chain / Oxidative Phosphorylation
29
In glycolysis, Glucose or glycogen must be converted, requiring energy. What is this cost?
``` Glucose = 1 ATP to convert. Glycogen = 2 ATP to convert ```
30
What are the product of glycolysis?
5ATP net yeild = 3ATP H2O Pyruvate Converted to lactate by Lactate dehydrogenase
31
The process of forming a product that can enter the krebs cycle produces what as a biproduct?
Hydrogen ions (acidifies the environment) and CO2
32
What prevents the environment from acidfying?
The electron transport chain accepts Hydrogen ions from the Krebs cycle / process and produces 34ATP as a result and water.
33
How many ATP does the krebs cycle produce?
2 ATP
34
What prevents glycolysis from being a long term provider of energy apart from being inefficient?
Lactate formation inhibits the glycolysis cylcle
35
Are carbohydrates the only thing that can enter the krebs cycle?
No Proteins and fats can to. In fact fats produce a total of 129ATP (including the e transport chain)
36
What are the three types of muscle fibres?
Type I Type IIa Type IIb
37
What is the implication of three different muscle fibres?
Different mechanisms for energy production
38
What are the energy mechanisms of type I fibres?
Type I Slow twitch - fatigue resistant Oxidative
39
What are the energy mechanisms of Type IIa fibres?
Type IIa Fast twitch - powerful Oxidative-glycotic
40
What are the energy mechanisms of type IIb fibres?
Type IIB Fast Twitch - powerful Glycotic
41
How can the relative number of mitochondira in a fiber be determined?
Primary method of ATP production, if oxidative then high mitochondria
42
Does each muscle have the same proportion of muscle fibre types?
No, Each muscle has different ratio of fibres depending on action and usage
43
What are the relative energy stores of a 70kg man?
Fat = 10500g = 378000kJ Muscle Glyogen = 350g = 5600kJ Liver Glycogen = 100g = 1600kJ Blood Glycogen = 20g = 320 KJ Protein = 9000g = 153000kJ
44
What are the five methods of ATP production during exercise and the time it takes for each method to kick in?
``` Fat Oxidation 2+ hrs Blood Glucose Oxidation 90mins Glycogen Oxidation 1-3mins Glycolysis 5-10sec PCr breakdown instantaneous ```
45
With the five methods of ATP production, which produce the greatest quantity of ATP the fastest?
``` Fat Oxidation Slowest Blood Glucose Oxidation Glycogen Oxidation Glycolysis PCr breakdown Fastest ```
46
What is the cross over concept?
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
What is the function of enzymes in energy release?
Enzymes control most of the energy reactions within a cell.
48
What are some examples of enzyme regulation?
Freeing of triglycerides - hormone sensitive lipase Breakdown of glycogen - glycogen phosphorylase Reactions of glycolysis - Hexokinase Reactions of the TCA Cycle - Citrate synthase
49
What regulates enzyme function?
Temperature Concentrations pH Substances that bind to enzymes e.g hormones
50
Where do hormones for the regulation of metabolism normally reside?
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
What are the two possible uses of metabolic hormones?.
Anabolism or Catabolism
52
What are the Metabolic Hormones to be known for this course?
``` Insulin Glucagon Growth Hormone Cortisol Epinephrine Norepinephrine ```
53
Where is insulin released from and what is its effect?
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
Where is glucagon released from and what is effects?
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
What is the function of growth hormone and where is it released from?
Growth hormone is released from the Anterior pituitary. Anabolic or Catabolic Promotes triglyceride breakdown Increases protein synthesis
56
What is the function of cortisol and where is it released from?
Released from the zona fasiculus of the adrenal cortex. Catabolic * Increases breakdown of protein * Stimulates making of new glucose * Stimulates breakdown of fat
57
What is the function of epinephrine?
* Secreted from adrenal medulla (and nerves) * Fight or Flight response * Glycogenolysis in muscle * Lipolysis in fat * Catabolic
58
How does exercise manipulate energy efficiency?
``` • 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 ```

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