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A-LEVEL P.E YEAR 13 > 8.1 Energy Systems > Flashcards

8.1 Energy Systems Flashcards

1
Q

What is the ATP-PC system and what does it stand for?

A
  • ATP-PC - Adenosine Triphosphate Phosphocreatine- the only usable form of energy in the body
  • Its an energy system using phosphocreatine (PC) as its fuel
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2
Q

What is phospocreatine and where is it found?

A
  • PC is an energy-rich phosphate compound found in the sarcoplasm of the muscles & can be broken down quickly & easily to release energy to resynthesise ATP
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3
Q

How long does the ATP-PC system last for?

A
  • There is only enough PC to last for 5-8 seconds
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4
Q

What does ATP consist of?

A
  • Consists of one molecule of adenosine and three (tri) phosphates
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5
Q

How does the ATP-PC system work to provide energy?

A
  • ATP-PC system is an anaerobic process & re-synthesises ATP when the enzyme creatine Kinase detects high levels of ADP
  • It breaks down the phosphocreatine in the muscles to phosphate & creatine, releasing energy
  • This energy is then used to convert ADP to ATP in a coupled reaction
  • For every 1 molcule of PC broken down there is enough energy released to create 1 molecule of ATP
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6
Q

What are the advantages and disadvantages of the ATP-PC system?

A

Advantages:
- ATP can be resynthesised rapidly using the ATP-PC system
- PC stores can be resynthesised quickly - (30s=50% replenishment & 3mins=100%)
- There are no fatiguing by products
- It is possible to extend the time the ATP-PC system can be utilised through use of creatine supplementation

Disadvantages:
- There is only a limited supply of phosphocreatine in the muscle cell, i.e can only last for 10 seconds
- Only one mole of ATP can be re-synthesised for every mole of PC
- PC re-synthesis can only take place in the prescence of oxygen (i.e when the intensity of the exercise is reduced)

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7
Q

How does the body constantly rebuild ATP?

A
  • By converting the ADP & Pi back into ATP
  • We can resynthesise ATP from 3 different types of chemical reactions in the muscle cells
  • These chemical reactions are fuelled by either a food or a chemical called phosphocreatine found in the muscles
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8
Q

What are the three energy systems that the conversion of energy into this fuel takes place in?

A
  • The aerobic system
  • The ATP-PC system
  • The anaerobic glycolytic system
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9
Q

When is the aerobic system used and what does it do?

A
  • Used when exercise intensity is low & oxygen supply is high
  • This system breaks down glucose into carbon dioxide & water which in the prescence of oxygen is much more efficient
  • Up to 38 molecules of ATP can be produced
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10
Q

What are the 3 stages of the aerobic system?

A
  • Glycolysis
  • Krebs Cycle
  • Electron Transport Chain

REMEMBER ORDER: Get Kintetic Energy (GLYCOLYSIS, KREBS,ELECTRON)

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11
Q

What is the glycolysis stage?

A
  • This 1st stage is anaerobic so it takes place in the sarcoplasm of the muscle cell
  • Glycolysis is the breakdown of glucose to pyruvic acid
  • For every molecule of glucose undergoing glycolysis, a net of two molecules of ATP is formed
  • Before the pyruvic acid produced in glycolysis can enter the next stage (Krebs cycle) it is oxidised into two acetyl groups & is then carried into Krebs cycle by coenzyme A
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12
Q

What happens in the Krebs cycle?

A
  • The two acetyl groups diffuse into the matrix of the mitochondria where Krebs cycle occurs
  • Here the acetyl groups combine with oxaloacetic acid, forming citric acid
  • Hydrogen is removed from the citric acid & the rearranged form of citric acid undergoes ‘oxidative carboxylation’ means that carbon & hydrogen are given off.
  • The carbon forms carbon dioxide which is transported to the lungs & breathed out & the hydrogen is taken to the electron transport chain
  • The reactions that occur result in the production of two molecules of ATP
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13
Q

What happens during the electron transport chain?

A
  • Hydrogen is carried to the electron transport chain by hydrogen carriers
  • This occurs in the cristae of the mitochondria & the hydrogen splits into hydrogen ions & electrons & they are charged with potential energy
  • The hydrogen ions are oxidised to form water while the hydrogen electrons provide the energy to re-synthesise ATP
  • Through this process 34 ATP are formed
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14
Q

What is beta oxidisation?

A
  • Stored fat is broken down into glycerol & free fatty acids for transportation by the blood
  • These fatty acids then undergo a process called beta oxidisation whereby they are converted into acetyl coenzyme A, which is the entry molecule for the Krebs cycle
  • From this point on, fat metabolism follows the same path as glycogen metabolism.
  • More ATP can be made from one molecule of fatty acids than one molecule of glucose
  • Which is why in long duration, low intensity exercise fatty acids will be the predominent energy source

(Fat in regards to the aerobic system)

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15
Q

What are the advantages & disadvantages of the aerobic system?

A

Advantages:
- More ATP can be produced 36 ATP
- There are no fatiguing by-products (co2 & water)
- Lots of glycogen & triglyceride stores so exercise can last a long time

Disadvantages:
- This is a complicated system so cannot be used straight away, it takes a while for enough oxygen to become avaliable to meet the demands of the activiy & ensure glycogen & fatty acids are completely broken down
- Fatty acid transportation to muscles is low & also requires 15% more oxygen to be broken down than glycogen

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16
Q

What does the short-term lactate anaerobic system/ anaerobic glycolytic system do?

A
  • Provides energy for high intensity activity for longer than the ATP-PC system
  • However how long this system lasts depends on the fitness of the indiviudal & how high the exercise intensity is
  • Working flat out to exhaustion will mean the system will last a much shorter time as demand for energy is extremely high
  • The anaerobic glycotic system re-synthesises ATP from the breakdown of the fuel glucose- this is supplied from the digestion of carbohydrates & is stored in the muslces & liver as glycogen, where it is readily avaliable

e.g. in practice an elite athlete who has just run the 400m in under 45 seconds will not be able to immediately run it again at the same pace, however reduce the intensity a little & the system can last up to 2-3 minuets because the demand for energy is slightly less

17
Q

How does the anaerobic glycotic system work to provide energy?

A
  • When the PC stores are low, the enzyme glycogen phosphorylase is activated to break down the glycogen into glucose which is then further broken down to pyruvic acid by the enzyme phosphofructokinase
  • This process is called anaerobic glycolysis & takes place in the sarcoplasm of the muscle cell where oxygen is not avaliable
  • Since this is an anaerobic process, the pyruvic acid is then further broken down into lactic acid by the enzyme lactate sehydrogenase (LDH)
  • During anaerobic glycolysis energy is released to allow ATP re-synthesis
  • The net result is two molecules of ATP are produced for one molecule of glucose broken down
18
Q

What are the advantages & disadvantages of the anaerobic glycolytic system?

A

Advantages:
- ATP can be resynthesised quite quickly due to very few chemical reactions & lasts for longer than the ATP-PC system
- In the prescence of oxygen, lactic acid can be converted back into liver glycogen or used as a fuel through oxidation into carbon dioxide & water
- It can be used for a sprint finish

Disadvantages:
- Lactic acid as the by-product - the accumulation of acid in the body denatures enzymes & prevents then increasing the rate at which chemical reactions take place
- Only a small amount of energy can be released from glycogen under anaerobic conditions
(5% as opposed to 95% under aerobic conditions)

19
Q

What is the energy continuum of physical activity?

A
  • A term which describes the type of respiration used by physical activities, whether it is aerobic or anaerobic respiration depends on the intensity & duration of the exercise
20
Q

Explain the energy continuum of physical activity.

A
  • The energy continuum is often explained in terms of thresholds
  • The ATP-PC/anaerobic glycolytic threshold is the point at which the ATP-PC energy system is exhausted by the intensity of the exercise & the anaerobic glyolytic/aerobic threshold (at 3 mins) is the point at which the anaerobic glycolytic system is exhausted & the aerobic system takes over
21
Q

What are the differences in ATP between fast & slow twitch muscle fibres?

A

Slow twitch (Type II)
- Main pathway for ATP production is in the aerobic system
- It produces maximum amount of ATP avaliable from each glucose molecule (up to 36 ATP)
- Production of ATP is slow but these fibres are more endurance based so less likely to fatigue

Fast twitch (Type II X)
- Main pathway for ATP production is via the lactate anaerobic energy system (during glycolysis)
- ATP production in the abscence of oxygen is not efficient- only 2 ATP produced per glucose molecule
- Production of ATP this way is fast but cannnot last for long as these fibres have least resistance to muscle fatigue

22
Q

Define ‘oxygen consumption’

A
  • The amount of oxygen we use to produce ATP
23
Q

What is a sub-maximal oxygen deficit and what does it do?

A
  • When we start to exercise, insufficient oxygen is distributed to the tissues for all the energy to be provided aerobically
  • This is because it takes time for the circulatory system to respond to the increase in demand for oxygen & it also takes time for the mitochondria to adjust to the rate of aerobic respiration needed
  • As a result energy is provided anaerobically to satisfy the increase in demand for energy until the circulatory system & mitochondria can cope
24
Q

What is the maximum oxygen deficit?

A
  • Usually referred to as maximal accumulated oxygen deficit or MAOD
  • Gives an indiciation for anaerobic capacity
  • Oxygen deficit is bigger during maximal exercise as the performer is short of more oxygen at the start as they have to work more anaerobically
25
Q

What is excess post-exercise oxygen consumption (EPOC)?

A
  • Increased rate of oxygen intake following activity, intended to pay back the oxygen deficit.

There are two components:
- Fast (alactic) component
- Slow (lactic) component

26
Q

What is the fast component (alactacid component) to EPOC?

A
  • Fast replenishment stage uses the extra oxygen that is taken in during recovery to restore ATP & phosphocreatine & to re-saturate myoglobin w oxygen
  • Complete restoration of phosphocreatine takes up to 3 minuets
  • But 50% of stores can be replenished after only 30 seconds during which time approx 3 litres of oxygen are consumed
27
Q

What does myoglobin do within the fast component of EPOC?

A
  • Myoglobin has high affinity for oxygen
  • It stores oxygen in the sarcoplasm that has diffused from the haemoglobin in the blood
  • After exercise oxygen stores in the myoglobin are limited
  • The surplus of oxygen supplied through EPOC helps replenish these stores taking up to 2 minuets & using approx 0.5 litres of oxygen
28
Q

What is the slow component (lactacid component) and what are its functions?

A

Oxygen consumed during the slow replenishment stage (lactacid component) has several functions:
- Removal of lactic acid
- Maintenance of breathing & heart rates
- Glycogen replenishment
- Increase in body temperature

29
Q

What is the Cori Cycle?

A
  • This takes place in the slow component
  • The process where lactic acid is transported to the liver where it is converted to blood glucose and glycogen
30
Q

What is the removal of lactic acid stage?

A
  • Lactic acid accumulates during exercise & during recovery it needs to be removed
  • Full recovery may take up to an hour/ longer, depending on intensity & duration of exercise
31
Q

What ways can lactic acid be removed?

A
  • When oxygen is present, lactic acid can be converted back into pyruvate & oxidised into carbon dioxide & water in the inactive muscles & organs - this can then be used by muscles as an energy source
  • Transported in the blood to the liver where it is converted to blood glucose & glycogen (the Cori cycle)
  • Converted into protein
  • Removed in sweat & urine

The majority of lactic acid can be oxidesd in mitochondria so performing a cool-down can accelerate its removal
This is because exercise keeps the metabolic rate of muscles high & keeps capillaries dilated which means oxygen can be flushed through removing the accumulated lactic acid
The slow replenishment stage of recovery begins as soon as lactic acid appears in the muscle cells & will continue using breathed oxygen until recovery is complete.

32
Q

What is the maintenance of breathing & heart rates stage?

A
  • Maintaining a breathing & heart rates requires extra oxygen to provide the energy needed for the respiratory & heart muscles
  • This assists recovery as the extra oxygen is used to replenish ATP & phosphocreatine stores, resaturate the myoglobin & remove lactic acid, therefore returning the body back to its pre-existing state
33
Q

What is the glycogen replenishment stage?

A

-Glycogen is the primary energy source for both aerobic & anaerobic glycotic systems & is depleted during exercise.
- Recovery depends on the exercise type & post-exercise carbohydrate intake.
- After a marathon, glycogen restoration may take days, but after high-intensity, short-duration exercise, it can be restored within an hour through the Cori cycle, which converts lactic acid back to glucose & glycogen.
- Eating a high-carb meal within an hour after exercise speeds up glycogen replenishment.

34
Q

What is the increased body temperature stage?

A
  • When temperature remains high, respiratory rates will also remain high & this will help the performer take in more oxygen during recovery
  • However extra oxygen (from the slow component of EPOC) is needed to fuel this increase in temperature until the body returns to normal

A-LEVEL P.E YEAR 13 (12 decks)

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