8 mark answers A2 PE Physiology
Sliding Filament Theory
A. Filaments unable to bind due to tropomyosin
B. Receipt of nerve impulse/action potential/electrical impulse/wave of depolarisation
C. Sarcoplasmic reticulum (releases)
D. Calcium (ions released)
E. (Calcium) Attach to troponin (on actin filaments)
F. Causes change of shape of troponin/moves tropomyosin
G. Exposes myosin binding site (on actin filament)/ ATP
H. Cross bridge formation
I. Power stroke occurs/Ratchet Mechanism/Reduce H zone/z lines closer together
Motor unit
1. Motor neurone and muscle fibres;
2. All fast-twitch or slow-twitch/ homogenous;
3. All or none law
A. (Greater the force needed) larger motor units recruited
B. More units recruited
C. Need fast twitch fibres rather than slow twitch fibres
D. Multiple unit summation/spatial summation
E. All or none law/All or nothing law/or explanation
F. Wave summation/frequency of impulse/innervations
G. Motor unit unable to relax/increase the force
H. Tetanus/titanic for powerful contraction
I. Muscle spindles detect changes in muscle length/speed of contraction
8 mark answers A2 PE Physiology
Aerobic System
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When oxygen is in rich supply, pyruvic acid is converted into acetyl-coenzyme by combining
with pyruvate dehdrogenase
This site for energy release now moves to mitochondria
These industrial units in abundance within muscle and manufacture energy for ATP
resynthesis by facilitating many chemical reactions required to break down stores of
glycogen and fats for continuous supply of energy
Mitochondria is usually found in large numbers in slow twitch muscle fibres
Krebs cycle
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Takes place in fluid-filled matrix of mitochondria
Three significant events occur at this stage:
1) Oxidation of citric acid – involves removal of hydrogen atoms from compound which
enter final stage of aerobic system; electron transport system
2) Production of carbon dioxide – removal of hydrogen means carbon and oxygen remains.
They combine to form CO2, which is carried to the lungs and breathed out
3) Resynthesis of ATP – sufficient energy released to resynthesise 2 molecules of ATP
Electron Transport System
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Final stage of glycogen breakdown occurs in cristae of mitochondria. Hydrogen carried to
electron transport system from Krebs cycle
Two important features of this stage of aerobic pathway:
1) Water is formed when hydrogen ions and electrons combine through series of enzyme
reactions
2) Resynthesis of ATP: majority of energy released here for resynthesis of ATP. 34
molecules of ATP resynthesised.
8 mark answers A2 PE Physiology
Explain threshold though energy continuum
Onset of blood lactate accumulation (OBLA)
During higher intensity activity lactate levels rise.
Blood lactate levels at rest and during aerobic activity (remember during aerobic activity lactic acid is
not produced) is aprox 2mmol/L(2 millimoles per L of blood).
When blood lactate begins to rise during anaerobic activity and lactate levels reach 4 mmol/L,
it is said to be the onset of blood lactate accumulation – OBLA.
If the activity intensity continues or increases OBLA will continue to rise.
The result of this is:
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Lower blood pH (increased blood acidity)
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Inhibition of enzyme action
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Pain receptors stimulated
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Muscle fatigue/pain
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Reduction in performance
8 mark answers A2 PE Physiology
Define oxygen deficit:
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the amount of O2 that would have been used if it was available
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The volume of extra oxygen required to complete the entire activity aerobically.
During and following a game of rugby, performers will experience Excess Postexercise
Oxygen Consumption or EPOC. What is this excess oxygen being used for?
3 marks for 3 of:
1. Re-saturation of myoglobin (with oxygen)
2. To restore/remake/resynthesis/ATP/PC/ATP-PC
3. Used to remove lactate/lactate acid
4. Maintain high breathing rate/heart rate/metabolic rate/temperature
Describe the fast and slow component of recovery
The oxygen debt is made up of two components. How much do each of these contribute to the
recovery process? 6 marks
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Oxygen debt is made up of the slow and fast components
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Fast component is the first component of EPOC,
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The O2 consumed is to resaturate myoglobin and resynthesize ATP and PC
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Takes approximately 2-3 minutes
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Slow component is the second component of EPOC
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Represents glycogen stores
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Helps the removal of lactic acid
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Maintains cardiac and respiratory rate
(ii) Explain how the functions of the slow component are achieved. (3 marks)
(ii) 1. Removal of lactate/lactic acid;
2. By oxidation/aerobic energy production;
3. In other organs (liver)/muscles/Cori cycle;
4. Conversion to pyruvate- used as energy source;
5. To water and carbon dioxide;
6. Conversion to glycogen / glucose;
7. Some converted to protein / some excreted in sweat and / or urine;
8. Oxygen used to maintain high work rates of heart / breathing muscles;
9. Extra oxygen used as temperature remains high;
3 marks
c) In terms of recovery, explain the relationship between lactate threshold and the functions of
Excess Post-exercise Oxygen Consumption (EPOC). (5 marks)
1. Lactate removed during EPOC
2. Slow/lactacid component
3. Oxygen used/needed for aerobic energy/ATP production formation
4. Lactate mainly converted back into pyruvate
5. Mitochondria/Kreb’s cycle/to CO2 and H2O
6. In inactive muscles/other organs (liver)
7. Some lactate converted to glucose/glycogen/protein
8. Cori cycle
9. Some excreted in urine and sweat
8 mark answers A2 PE Physiology
Creatine
Extends the threshold of the ATP-PC system by making phosphocreatine readily available in the
muscles. Used by a variety of athletes such as sprinters and weightlifters.
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Adv – Boosts maximal strength, increases lean muscle mass.
Dis – Abdominal cramps, water retention, bloating, weight gain, diarrhoea.
Herbal Remedies
Organic sport supplement
 Adv – Reduces body fat, increases hormone levels, increases muscle mass, enhances energy,
improves stamina.
 Dis – Unknown side effects.
Bicarbonate of soda
Increases the pH of the blood enhancing the buffering capacity of the blood improving its ability to
remove negative effects of Lactic Acid. Used by athletes working at high intensities.
 Adv- Removes negative effects of lactic acid, allows performers to work for longer periods.
 Dis – Stomach cramps, nausea, bloating, diarrhoea.
Caffeine
Mild stimulant that occurs naturally and is predominantly found in coffee.
 Adv – Beneficial for endurance athletes
 Dis – dehydration, sleep deprivation, muscle and abdominal cramping.
Protein Supplements
Useful for those who have trouble fitting regular meals, it is also used by a wide variety of athletes
especially strength athletes.
 Adv – used to enhance muscle repair and growth, can increase endurance and increase
muscle mass.
 Dis – diets high in protein puts a strain on the liver and kidney.
HGH
A synthetic product that mimics the body’s natural growth hormone. It can promote protein
synthesis.
 Adv – increases lean muscle mass, increase in strength, and decrease in body fat.
 Dis – heart failure, high blood pressure, abnormal development of bone tissue that causes
the broadening of facial features.
Anabolic Steroids
A group of synthetic hormones that promote the storage of protein and the growth of tissue. Used
by athletes such as weightlifters and rugby players.
 Adv – increase in muscle size and strength.
 Dis – heart failure, increased aggression, liver damage, development of masculine effects.
8 mark answers A2 PE Physiology
Beta Blockers
A group of hormones that are used by performers to lower metabolic activity.
 Adv – Decreases heart rate, reduces blood pressure, steadies nerves.
 Dis – low blood pressure and chronic fatigue.
Glycogen loading
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Endurance athletes, e.g. marathon runners, rely on their stores of glycogen as a source
of energy during competition.
Carbohydrate loading is a legal method of boosting the amount of glycogen in the body prior
to a competition.
Six days prior to a competition, the process begins.
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For the first three days the athlete consumes minimal carbohydrate and exercises so as to
deplete the bodies glycogen stores
In the first three days, ensure adequate carbohydrates are consumed to maintain the
functioning of several important systems in the body.
In the last three days the athlete consumes primarily carbohydrate and reduces the training
load
Possible Side effects
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Muscle stiffness
Diarrhoea
Chest Pain
Depression
Lethargy
Water and electrolyte balance
 Water is an essential nutrient of an athlete’s diet,
 Especially important to endurance athletes.
 Recommended that athletes drink between 400ml-500ml 15 minutes before training or
competition
 During competition 150-200ml should be taken every 15-20 minutes
 Fluid recovery should take place during recovery to maintain blood glucose levels.
 Replaces lost fluids, electrolytes, and potassium and chlorine form electrolytes.
 Helps to maintain the correct exchange of nutrients and waste products into and out of
the muscle cell
If conducted incorrectly:
 Blood thickens
 Increase in heart rate
 Reduction in blood flow
 Slow reaction time
8 mark answers A2 PE Physiology
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Muscle fatigue
Muscle cramps
Irregular heart beat
Describe projectile motion, including the factors affecting distance and vector components of
parabolic flight.
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Velocity of release- increase in velocity will increase the horizontal component of the
projectile.
Height of release – increase in the release height will increase the horizontal component in
the projectile.
Angle of release – Optimum angle of release is 45 degrees.
Parabolic – Air resistance has a minimal affect.
Distorted parabola – More effects of weight/gravity.
Explain the concept of angular motion and how it is conserved during flight.
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Angular motion – This occurs whenever a force acts outside the centre of mass of a body or
object.
Off-centre force is known as an eccentric force and is necessary if rotation is to occur.
Moment of inertia – A measure of the resistance of a body to change its state of angular
motion.
When body has increased moment of inertia – less distribution in the body mass causing
decrease in velocity.
When a body has decreased moment of inertia – More distribution in the body mass causing
an increase in velocity.
Describe the moment of inertia and explain its relationship with angular velocity.
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Moment of inertia – A measure of the resistance of a body to change its state of angular
motion.
Angular velocity – the angular displacement travelled in a specified time.
An increase in the moment of inertia – Decrease in angular velocity.
Due to the increase distribution of mass.
A decrease in moment of inertia – Increase in angular velocity.
Due to the decrease in the distribution of mass.