Describe nervous control of ventilation during exercise.

Describe the resynthesis of adenosine triphosphate (ATP) by the lactic acid (anaerobic glycolysis) system.

Outline three general features of muscle tissue.

An attacking football player moves in one direction and immediately changes to the opposite direction. This deceives the defender.

Explain the concept the attacking player is using to evade the defender.

Discuss the structure and function of the leg muscle fibres of an elite long jumper and a marathon runner.

nervous system:

breathing is manipulated by the autonomic nervous system to increase rate <expiratory centre> & increase depth <inspiratory centre> of breathing in response to exercise;

respiratory centre is found in the brain stem / medulla oblongata & pons in the brain;

chemoreceptors relay information to the respiratory centre regarding lower pH or O₂ / higher CO₂ levels

OR

proprioceptors relay information to the respiratory centre regarding action of muscles / spindles / joint receptors;

<inspiratory> respiratory centre increases stimulation <via phrenic nerve and intercostal nerves> to the inspiratory muscles <external intercostals and diaphragm>;

during exercise inspiratory muscles are stimulated to contract more forcefully;

<inspiratory> respiratory centre stimulates additional accessory muscles <sternocleidomastoid, pectoralis minor, scalenes> to contract <to increase depth of breathing>;

during forceful ventilation nerve impulses from the inspiratory area activate the expiratory area;

stretch / mechano receptors in the lungs <and bronchioles> relay information to the respiratory centre to prevent over inflation of the lungs;

in response to stretch receptors, <expiratory> respiratory centre shortens the duration of inspiration / Hering-Bruer reflex;

<expiratory> respiratory centre stimulates expiratory muscles <internal intercostals / obliques / rectus abdominus> to contract;

expiration moves from passive to active control during exercise;

Max [2] if no reference to exercise.

system can only use glycogen/glucose as a fuel source;

glucose is converted into pyruvate;

system produces a low yield / 1 glucose produces 2ATP <net>;

in the absence of oxygen pyruvate is converted to lactate/lactic acid;

byproducts of lactic acid system are lactic acid, <hydrogen ions, lactate>;

system resynthesizes ATP at a rapid rate;

contractility: capacity to shorten under tension;

extensibility: stretches beyond resting length when other muscles act across a joint;

elasticity: ability to return to resting length after being stretched beyond its normal resting length;

atrophy: the partial or complete wasting away of muscle; muscular hypertrophy: the enlargement of muscle from the

increase in size of its cells;

controlled by nerve stimuli and fed by capillaries;

psychological refractory period;

is the increase in response time (RT) to a second stimulus caused when the second stimulus has been delivered while the performer is responding to the first stimulus

OR

time delay in RT caused by the arrival of a second stimulus before the first is processed

OR

when a second stimulus arrives before the first response is completed;

reaction to the second stimulus is longer as the first response is still being processed

OR

player has to sort out new and correct stimulus, but first they have to disregard the old and now useless stimulus and this causes the delay;

hoping the defender has been distracted by the fake move as they cannot respond until the full reaction/response 1 has been processed by the brain;

brain processes one action at a time causing a time delay in responding to the second stimulus

OR

the single channel hypothesis states that each stimulus can only be processed one at a time

OR

a second stimulus must wait until the first has been processed

OR

each stimulus we process has to progress through a single track

OR

any subsequent stimulus must wait for the one before it to be processed before it can be dealt with;

Award [1] stating for the concept.

Accept diagram to assist with explanation.

Require an explanation for mark, candidates cannot just list structural and functional characteristics.

Max [4] for either athlete.

This was a poorly answered question. Many candidates completely misinterpreted the question and described the mechanics of breathing with no reference to exercise. Many of those who understood the requirements of the question focused on cardiovascular control rather than ventilatory control. Those who were able to access marks described the receptors involved but struggled to describe how this information was used to effect changes in breathing during exercise.

Of the candidates who selected question 4, many chose not to respond to this question. Surprisingly many candidates struggled to access full marks for this question. Most were able to identify glucose as the fuel and a net of 2ATP and a by-product of lactic acid.

Most candidates attempted this question with many able to outline that an increase in hemoglobin resulted in an increase in oxygen delivery. However not all of these candidates referred to the increased delivery to working muscles. From this some candidates were able to identify that this would increase the ability to work for longer periods/at a higher intensity or that there would be a greater exchange of oxygen at the muscles. Very few candidates were able to access 3-4 marks for this question as they were unable to apply the adaptation of training to the physiological and performance response.

Most candidates who attempted question 4 addressed this question. Many were able to explain that an athlete must complete their response to the first stimulus before they can respond to the second stimulus and that the introduction of a dummy fake as the first stimulus causes a delay in response. However few candidates referred to the single channel hypothesis or were able to identify the concept.

Of candidates who chose to answer question 4, many did not attempt this question. Candidates were required to discuss the structural and functional characteristics of the muscle fibres of two contrasting athletes. Most candidates were able to identify the correct dominant muscle fibre type for each sport. However, many struggled to identify the appropriate characteristics of these fibre types. For candidates who were able to accurately identify the appropriate characteristics they were often a list rather than a discussion. Candidates were required to apply their knowledge of the characteristic and provide more detail as to how this would enable the athlete to complete the relevant sport.