Sport

• Name the muscle fibre type in use during an endurance race and identify the physiological characteristics that allow these muscles fibres to work for extended periods of time (3)

  - Type 1 muscle fibres

  - high number of mitochondria

  - high capillary density

  - high myoglobin
• Explain how 4 characteristics of type Iix muscle fibres enable them to be suited to anaerobic physical activities (4)

  - high levels in phosphocreatine allows high rate of contraction

  - high force production allows for an increase in speed of contraction

  - high actin and myosin allows for a faster contraction

  - high stores of PC allows the maintenance of high rate contraction for longer periods of time
• Suggest 3 physiological causes of muscle fatigue (3)

  - build up of lactic acid

  - lack of calcium ions

  - lack of acetylcholine
• Suggest why the muscles concerned in maintaining the trunk posture of the body of a sprinter might be expected to have a larger percentage of slow twitch muscle fibres (2)

  - they have to maintain posture for long period of time

  - it is important for these muscles to not fatigue as easily

  - therefore there is no need for them to have fast twitch fibres which are for powerful contractions
• Explain why fast twitch muscle fibres may build up an oxygen debt during a 400m sprint (3)

  - low capillary density

  - few mitochondria

  - therefore less O2 is supplied because they contain fewer oxidative enzymes
• How can a performer vary the strength of muscular contractions to ensure that a skill is completed correctly (4)

  - recruit larger motor units

  - recruit more motor units

  - use fast twitch muscle fibres rather than slow twitch

  - all or none law
• The strength of a muscle contraction involves the use of motor units. How are motor units used to produce muscle contractions of varying strength in a lift (3)


  - number of motor units used could be varied

  - all or none law

  - size of motor units can be varied
• Explain how training can adjust the recruitment of different fibre types (6)

  - low intensity endurance training will result in recruitment of slow twitch muscle fibres

  - high intensity will recruit more type IIx fibres

  - as the muscles get stronger, fewer fibres are required to produce the force needed

  - high intensity training will increase the rate of fibre recruitment
• Identify and explain the function of the different regions of a motor neurone (6)

  - cell body received stimuli from other neurones

  - via dendrites

  - axon conducts the electrical impulse

  - nodes of Ranvier allows the impulse to jump speeding up the rate of transmission

  - axon terminals transmits neurotransmitters such as acetylcholine
• What is a motor unit (2)

  - a motor unit consists of a block of muscle fibres connected to a motor neurone

  - this connects to the brain via the nervous system
• Why is it that all the muscle fibres attached to a motor neurone will not necessarily contract at the same time (3)

  - motor neurones have different lengths so the impulse takes less time in a shorter one

  - it may not be necessary for all motor units to be stimulates at the same time ( spacial summation)

  - motor units may be relaxing and resting
• The sliding filament hypothesis suggests muscular contraction occurs in the sarcomeres of the muscle fibres. Explain how actin and myosin filaments in the sarcomere bind together causing muscular contraction (4)

  - filaments are unable to bind due to tropomyosin

  - sarcoplasmic reticulum releases calcium ions which bind to troponin

  - this causes he shape of the troponin to change moving the tropomyosin out of the way

  - this exposes the binding site for myosin to attach to actin creating a cross bridge
• How are motor units involved in the process of spatial summation (2)

  - increases strength in muscles

  - use of more and bigger motor units
• Explain how a muscle contracts according to sliding filament theory (4)

  - action potential reaches the motor end plate

  - this causes calcium ions to be released to attach to troponin

  - this causes the tropomyosin to move revealing the actin binding sites

  - myosin attaches to actin forming a cross bridge and pulls on it
• Explain the roles of tropomyosin and troponin during a muscular contraction (4)

  - tropomyosin prevents myosin attaching to actin filaments

  - calcium ions attach to troponin in order to change the shape of the troponin so the tropomyosin binds to the troponin so the myosin binding site are exposed
• What is the effect of stimulating more motor neurones (1)

  increases strength/ force of contraction
• Describe the all or none law


  - when stimulated all the fibres within a motor unit will contract fully or not at all

  - there is no strong or weak contraction
• Compare wave summation and spacial summation firing patterns (4)

  - wave summation gradually increases the force of contraction as the muscle is stimulated again before it can fully relax

  - for example a gymnastics floor routine

  - spacial summation is where the motor units are turned on simultaneously to produce a constant force of contraction to prevent fatigue

  - for example a marathon runner
• Explain two reasons why actin and myosin may stop pulling on one another (4)

  - ATP is depleted

  - this is required to allow the myosin to break the cross bridge and move so without this there is no movement taking place

  - calcium is depleted

  - without calcium the tropomyosin will twist back and block the binding site of the actin preventing movement
• State why it is important to warm up muscle tissue prior to long jumping (2)

  - raises the muscle temperature to:

  --> increase enzyme action

  --> increase ATP conversion
• Describe three changes that occur in muscle cells as a result endurance training (3)

  - increase in muscle size (hypertrophy)

  - increase in number and size of mitochondria

  - increase in myoglobin content
• Examine the chronic adaptations to the cardiovascular system experienced after a sustained period of endurance training (8)

  - increase in cardiac output

  - hypertrophy of the heart

  - increase in blood volume

  - increased stroke volume

  - increase in capillary density allows for better gas exchange

  - increased haemoglobin allows better oxygen carrying capacity

  - increase in gas exchange in blood allows for faster delivery of oxygen

  - decrease incrusting heart rate (bradycardia)
• Describe the structures involved in gaseous exchange in the lungs and explain how gaseous exchange occurs within this tissue (6)

  - gaseous exchange is the delivery of oxygen from the lungs to the bloodstream and the elimination of carbon dioxide from the blood stream to the lungs

  - it occurs in the lungs between the alveoli and a network of capillaries

  - it depends on the particle pressure of each gas

  - it is done by a process called diffusion

  - moves down a concentration gradient
• Describe how oxygen is transferred from the alveoli to muscle at rest (4)


  - in the lungs oxygen is diffused into the capillaries from the alveoli

  - diffusion occurs from high concentration to low concentration

  - oxygen binds to haemoglobin in the red blood cells and transported to the muscles via the cardiovascular system
• Summarise the functions of three structural components of the cardiovascular system (3)

  - atria contract to push blood into the ventricle

  - ventricles contract to push blood into blood vessels

  - valves prevent the back flow of blood
• Describe how smoking adversely affects the respiratory system (6)

  - smoke contains chemicals that damage mucus producing cells that would normally trap pathogens

  - smoke irritates bronchi

  - smoke damaged the walls of the alveoli

  - reduces efficiency of gaseous exchange

  - carbon monoxide combines with haemoglobin reducing the ability to carry oxygen

  - increases risk of coronary heart disease
• Identify three healthy lifestyle changes to reduce diabetes risk (3)

  - engage in 30-60 mins of daily exercise

  - have a healthy diet

  - minimise alcohol consumption
• Describe the effects of an unhealthy lifestyle on the cardiovascular system (4)

  - stiffening of blood vessels

  - reduction in blood flow

  - increase blood pressure

  - increase stroke volume
• Outline the mechanical process of inspirational rest (4)

  - external intercostals contract

  - ribs move up and out

  - diaphragm contracts

  - thoracic cavity increases

  - pressure decreases

  - air moves in to the lungs down a pressure gradient
• Summarise how oxygen delivery to the working muscles increases during exercise (4)

  - increased tidal volume

  - increases cardiac output

  - increase blood pressure

  - vasodilation

  - vasoconstriction
• Define functional residual capacity (1)

  the amount air remaining in the lungs after normal expiration
• Define total lung capacity (1)

  the maximum amount of air that can fill the lungs
• Define vital capacity (1)

  maximum volume forcefully expired after a maximal inspiration
• Outline the change in 4 respiratory values during aerobic exercise (4)

  - inspiratory reserve volume decreases

  - expiratory reserve volume decreases

  - tidal volume increases

  - vital capacity decreases
• How is blood flow to various regions of the body controlled (4)

  - achieved by vasomotor control which creates a vascular shunt

  - vasodilation is the expansion of blood vessels to increase blood flow

  - vasoconstriction is the narrowing of blood vessels to decrease blood flow
• What is meant by the venous return mechanism (2)


  - the transport of blood from capillaries to the right atrium of the heart
• How is carbon dioxide transported in the blood (2)

  - combines with water to form carbonic acid

  - dissolves in plasma

  - combines with haemoglobin to form carbaminohaemoglobin
• Explain one reason why vascular shunting is necessary during a game of basketball (3)

  - transport more oxygen as it is required

  - lactic acid is continued to be removed

  - so they can work ar a higher intensity for longer by delaying fatigue