Respiratory system — AQA A-Level Physical Education

The respiratory system is responsible for the intake of oxygen and removal of carbon dioxide, essential for energy production during exercise. At A-Level, you must understand the anatomy of the respiratory tract, the mechanics of breathing (inspiration and expiration at rest and during exercise), and the control of breathing by the nervous system.

This topic underpins performance in physical activity, as efficient gas exchange directly affects aerobic capacity and endurance. It also links to other areas such as the cardiovascular system, energy systems, and training adaptations, making it a core component of the AQA A-Level Physical Education specification.

• →Structure of the respiratory system: nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, alveoli, and the role of the diaphragm and intercostal muscles.
• →Mechanics of breathing: inspiration and expiration at rest and during exercise, including the roles of the diaphragm, external and internal intercostal muscles, and accessory muscles.
• →Gas exchange: diffusion of oxygen and carbon dioxide across the alveolar-capillary membrane driven by partial pressure gradients.
• →Neural and chemical control: medulla oblongata, chemoreceptors (central and peripheral), and the role of blood pH, pCO2, and pO2.
• →Respiratory adaptations to training: increased tidal volume, vital capacity, pulmonary ventilation, and efficiency of gas exchange.

• Tidal volume is the volume of air inspired or expired in one normal breath at rest, approximately 0.5 dm³ in a healthy adult.
• Inspiratory reserve volume is the additional volume of air that can be forcibly inspired after a normal inspiration.
• Expiratory reserve volume is the additional volume of air that can be forcibly expired after a normal expiration.
• Vital capacity is the greatest volume of air that can be expelled from the lungs after a maximal inspiration, and it combines tidal volume with inspiratory and expiratory reserve volumes.
• Minute ventilation equals tidal volume multiplied by breathing frequency, so it rises during exercise because both factors increase.
• Regular training can increase vital capacity and tidal volume during exercise, improving the delivery of oxygen to working muscles.
• Residual volume is the volume of air remaining in the lungs after a maximal expiration.
• It cannot be exhaled and helps keep the alveoli and airways partly inflated, preventing lung collapse.
• Residual volume cannot be measured by simple spirometry because the air does not leave the lungs.
• Residual volume is excluded from vital capacity but is added to vital capacity to calculate total lung capacity.
• During exercise, residual volume remains relatively unchanged while tidal volume increases.
• ERV is the additional volume of air that can be forcibly exhaled after the end of a normal tidal expiration.
• It is measured by spirometry, with the subject exhaling maximally after a quiet breath out.
• Typical resting values are approximately 1.0–1.2 dm³ in healthy young adults.
• ERV is reduced when expiration is obstructed or when lung volumes are restricted.
• ERV is a primary lung volume and contributes to functional residual capacity and vital capacity.
• IRV is the additional volume of air that can be forcibly inhaled after the end of a normal tidal inspiration.
• It is measured by spirometry, with the subject inhaling maximally after a quiet breath in.
• Typical resting values are approximately 2.5–3.0 dm³ in healthy young adults.
• IRV is reduced when lung expansion is restricted, for example by restrictive disease or reduced chest compliance.
• IRV is a primary lung volume and contributes to inspiratory capacity and vital capacity.
• Tidal volume is the volume of air inspired or expired in one normal breath at rest.
• It is measured in dm³ or cm³, with a typical resting value of about 0.5 dm³ (500 cm³).
• It is read from a spirometer trace as the height of one resting breath, converted using the calibration.
• It is distinct from minute ventilation, which is tidal volume multiplied by breathing frequency.
• Tidal volume increases during exercise as breathing deepens, then plateaus near maximal lung use.
• Minute ventilation is the total volume of air breathed in or out in one minute.
• It is calculated as tidal volume multiplied by breathing frequency.
• A typical resting value is about 6 dm³ min⁻¹, for example 0.5 dm³ × 12 breaths per minute.
• It is expressed in dm³ min⁻¹ or litres per minute.
• It rises during exercise because both tidal volume and breathing frequency increase.
• Oxygen diffuses from alveolar air into pulmonary capillary blood down a partial pressure gradient.
• Carbon dioxide diffuses from pulmonary capillary blood into alveolar air down its partial pressure gradient.
• At muscles, oxygen diffuses from blood into muscle fibres because muscle partial pressure of oxygen is lower.
• Carbon dioxide produced by muscle respiration diffuses from muscle fibres into the blood.
• Alveoli and muscle capillaries have large surface areas, thin walls and short diffusion distances that make exchange efficient.
• Myoglobin in muscle aids oxygen storage and transport, helping maintain the diffusion gradient.
• Oxygen is transported mainly as oxyhaemoglobin in red blood cells, with a small amount dissolved in plasma.
• Carbon dioxide is transported dissolved in plasma, bound to haemoglobin as carbaminohaemoglobin, and as hydrogencarbonate ions.
• At alveoli, oxygen loads onto haemoglobin and carbon dioxide is unloaded into alveolar air.
• At muscles, oxygen unloads from haemoglobin into muscle fibres and carbon dioxide loads into blood.
• Partial pressure gradients determine the direction of diffusion for each gas.
• The difference between alveolar and blood partial pressures maintains continuous exchange.
• Diffusion is the passive net movement of gas molecules from higher to lower partial pressure, down a gradient.
• Each gas in a mixture exerts its own partial pressure; oxygen in air is about 21.2 kPa and carbon dioxide about 0.04 kPa at sea level.
• At the alveoli, oxygen diffuses from alveolar air into deoxygenated blood because alveolar partial pressure of oxygen exceeds that in the arriving blood.
• Carbon dioxide diffuses from blood into alveolar air because blood partial pressure of carbon dioxide exceeds alveolar partial pressure of carbon dioxide.
• Fick's law: rate of diffusion is proportional to surface area and partial-pressure gradient, and inversely proportional to membrane thickness.
• A larger partial-pressure gradient, larger surface area or thinner respiratory membrane increases the rate of gas exchange.
• Neural control of pulmonary ventilation originates in the respiratory centres of the medulla oblongata and pons.
• Impulses travel via the phrenic nerve to the diaphragm and via intercostal nerves to the external intercostal muscles.
• During physical activity, proprioceptors in muscles and joints and the motor cortex stimulate the respiratory centres to increase ventilation.
• Central chemoreceptors in the medulla detect a rise in carbon dioxide, which lowers blood pH and stimulates increased ventilation.
• Peripheral chemoreceptors in the aortic arch and carotid bodies detect falls in oxygen and rises in carbon dioxide and stimulate increased ventilation.
• Chemical regulation adjusts the rate and depth of breathing to restore blood gas and pH balance during and after exercise.
• The autonomic nervous system controls involuntary breathing via the respiratory control centre (RCC) in the medulla oblongata.
• The sympathetic nervous system influences the RCC to increase the rate and depth of breathing during exercise.
• The parasympathetic nervous system influences the RCC to decrease the rate and depth of breathing during rest or recovery.
• The RCC sends somatic motor impulses via the phrenic and intercostal nerves to the respiratory muscles to enact these changes.
• Carbon dioxide is the main chemical stimulus for regulating pulmonary ventilation.
• Increased carbon dioxide levels during exercise lower blood pH, increasing blood acidity.
• Chemoreceptors detect this increase in carbon dioxide and decrease in pH.
• Chemoreceptors send impulses to the respiratory control centre, which sends somatic impulses via the phrenic and intercostal nerves to increase breathing rate and depth.
• Chemoreceptors detect chemical changes, including rising carbon dioxide concentration, falling pH and falling oxygen concentration in blood or cerebrospinal fluid.
• Chemoreceptors send impulses to the respiratory centres, which increase the rate and depth of pulmonary ventilation.
• Proprioceptors in muscles, tendons and joints detect movement and limb position, raising ventilation at the start of exercise.
• Baroreceptors in blood vessel walls detect changes in blood pressure and contribute to the regulation of ventilation during activity.
• Chemoreceptors detect rising carbon dioxide concentration, falling pH and falling oxygen concentration in blood or cerebrospinal fluid.
• Proprioceptors in muscles, tendons and joints detect movement and limb position and raise ventilation at the onset of exercise.
• Baroreceptors in blood vessel walls detect changes in blood pressure and contribute to regulation of ventilation.
• Receptor input is integrated by the respiratory centres, which adjust the rate and depth of pulmonary ventilation during physical activity.
• Smoking paralyses and destroys cilia, leading to mucus build-up and increased risk of respiratory infections.
• Irritants in smoke cause inflammation and narrowing of the airways, increasing the work of breathing.
• Smoking damages alveolar walls (emphysema), reducing the surface area available for gaseous exchange.
• Carbon monoxide from smoking binds to haemoglobin, reducing the blood's oxygen-carrying capacity.
• These respiratory impairments reduce oxygen delivery to working muscles, lowering aerobic performance and accelerating fatigue.
• Tar paralyses and destroys cilia, so mucus and pathogens accumulate and infection risk rises.
• Irritants cause inflammation and narrowing of airways, increasing airway resistance and the work of breathing.
• Tar and chemicals destroy alveolar walls, reducing alveolar surface area for gaseous exchange.
• Carbon monoxide binds haemoglobin more readily than oxygen, forming carboxyhaemoglobin and reducing oxygen transport.
• Nicotine raises heart rate and narrows blood vessels, increasing cardiac and respiratory demand.
• Reduced oxygen transport lowers aerobic capacity, so fatigue occurs sooner during endurance exercise.
• Oxygen is carried mainly as oxyhaemoglobin, bound reversibly to haemoglobin in red blood cells.
• A small proportion of oxygen is dissolved directly in blood plasma.
• Each haemoglobin molecule can bind up to four oxygen molecules, giving a high carrying capacity.
• Loading occurs at the alveoli where partial pressure of oxygen is high; dissociation occurs at tissues where it is lower.
• The oxyhaemoglobin dissociation curve is S-shaped, and a rightward shift releases more oxygen.
• Carbon dioxide, increased acidity and raised temperature shift the curve right (Bohr effect).

• 💡Learn each volume with its definition and a typical resting value so you can distinguish similar options quickly.
• 💡Use the relationship minute ventilation equals tidal volume multiplied by breathing frequency to reason about exercise responses rather than memorising isolated numbers.
• 💡When a question describes a trained performer, link larger vital capacity and tidal volume to greater oxygen delivery during activity.
• 💡Anchor the definition to the phrase 'after a maximal expiration' so you do not confuse residual volume with expiratory reserve volume.
• 💡Remember the equation: total lung capacity equals vital capacity plus residual volume.
• 💡If a question asks about spirometry traces, remember that residual volume will not be directly plotted as an exhaled volume.
• 💡Learn the definition as 'extra air forcibly exhaled after a normal expiration' and use those exact functional words in your answer.
• 💡Link ERV to a spirometer trace: identify the section below the tidal volume baseline that represents the forced extra exhalation.
• 💡Practise comparing ERV with the other lung volumes so you can eliminate distractors quickly in multiple-choice questions.
• 💡Learn the definition as 'extra air forcibly inhaled after a normal inspiration' and use those exact functional words in your answer.
• 💡Link IRV to a spirometer trace: identify the section above the tidal volume baseline that represents the forced extra inhalation.
• 💡Practise comparing IRV with the other lung volumes so you can eliminate distractors quickly in multiple-choice questions.
• 💡Learn the definition and a typical resting value so you can distinguish tidal volume from other lung volumes in a multiple-choice question.
• 💡Practise reading a spirometer trace: identify one resting breath, measure its height, then convert using the stated calibration.
• 💡Check the units offered in the options; 0.5 dm³ equals 500 cm³, so a correct value may appear in either unit.
• 💡Link tidal volume to exercise by noting that it increases with deeper breathing but does not rise indefinitely.
• 💡Write the equation as minute ventilation = tidal volume × breathing frequency before substituting values.
• 💡Check that breathing frequency is given per minute; convert if it is stated per other time period.
• 💡Keep units consistent, for example dm³ × min⁻¹ gives dm³ min⁻¹.
• 💡Use a typical resting calculation such as 0.5 dm³ × 12 to sanity-check whether an answer is plausible.
• 💡State the direction of movement for each gas at each site using the terms alveoli, blood and muscle.
• 💡Link each direction to the partial pressure gradient rather than saying gases simply move.
• 💡Use surface area, thin walls and short diffusion distance to explain efficiency of exchange.
• 💡Name the transport forms of oxygen and carbon dioxide precisely, including oxyhaemoglobin and hydrogencarbonate.
• 💡Link each transport form to the site where loading or unloading occurs.
• 💡Use partial pressure gradients to explain why each gas moves in a particular direction.
• 💡Read the question carefully to identify whether it asks about direction of diffusion, partial pressures or factors affecting rate.
• 💡When a question gives partial-pressure values, compare them explicitly to decide the direction of net diffusion for each gas.
• 💡Use the phrase 'down a partial-pressure gradient' rather than 'from high concentration to low concentration' when the data are partial pressures.
• 💡Check units: partial pressures are usually given in kPa, so keep the unit with the value in your reasoning.
• 💡When asked about regulation, separate your answer into neural and chemical mechanisms to ensure both are covered.
• 💡Name the specific structures: medulla oblongata, pons, phrenic nerve, intercostal nerves, central chemoreceptors, peripheral chemoreceptors, aortic arch and carotid bodies.
• 💡Link each receptor to the specific change it detects: carbon dioxide and pH for central chemoreceptors; oxygen, carbon dioxide and pH for peripheral chemoreceptors.
• 💡Explain the effect on ventilation: increased rate and depth of breathing to restore blood gas and pH balance.
• 💡Link the sympathetic nervous system to an increase in breathing rate and depth during exercise via the RCC.
• 💡Link the parasympathetic nervous system to a decrease in breathing rate and depth during recovery via the RCC.
• 💡Remember to state that the respiratory muscles are skeletal and receive somatic impulses from the phrenic and intercostal nerves, not direct autonomic impulses.
• 💡Always link an increase in carbon dioxide to a decrease in blood pH when discussing chemical control of breathing.
• 💡Name chemoreceptors as the specific sensory receptors that detect changes in carbon dioxide.
• 💡Explain the full sequence: increased carbon dioxide lowers pH, stimulating chemoreceptors, which activate the RCC to send somatic impulses to respiratory muscles.
• 💡Name the receptor, state what it detects and link it to the change in ventilation.
• 💡Use precise terms such as carbon dioxide concentration, pH and blood pressure rather than vague wording like 'chemicals'.
• 💡Check each option against the receptor's location and stimulus before choosing.
• 💡For each receptor, state its location, its stimulus and its effect on ventilation.
• 💡Use the exact terms carbon dioxide concentration, pH, blood pressure, movement and limb position.
• 💡Eliminate options that give a receptor the wrong location or the wrong stimulus.
• 💡Focus exclusively on smoking when asked about poor lifestyle choices affecting the respiratory system in this specific context.
• 💡Link the damage to specific structures (e.g., cilia, alveoli) to their functional consequence (e.g., reduced gaseous exchange).
• 💡Connect the respiratory damage from smoking to its ultimate effect on exercise performance, such as reduced aerobic capacity and earlier fatigue.
• 💡Name the harmful component, then state its specific effect on a named respiratory structure.
• 💡Use the chain cilia destroyed, mucus trapped, infection risk, airway resistance, reduced gaseous exchange for full-mark explanations.
• 💡Distinguish clearly between effects on the airways, the alveoli and oxygen transport when answering comparison questions.
• 💡Link each transport step to the partial pressure gradient, naming alveoli and tissues explicitly.
• 💡Use the terms loading, dissociation and oxyhaemoglobin precisely rather than vague wording.
• 💡When explaining a rightward shift, name the specific factors (carbon dioxide, acidity, temperature) and the effect on oxygen release.
• 💡Always use specific terminology such as 'partial pressure', 'diffusion gradient', 'medulla oblongata', and 'chemoreceptors' to access higher marks.
• 💡When explaining responses to exercise, structure your answer using the stimulus-receptor-coordinator-effector-response model to ensure logical flow.
• 💡For calculation questions, show all working and include units; marks are often awarded for correct units and intermediate steps.

• Confusing tidal volume with vital capacity: tidal volume is one normal breath at rest, whereas vital capacity is the maximum volume exhaled after a maximal inspiration.
• Assuming breathing rate alone explains the rise in minute ventilation during exercise: tidal volume also increases, so both factors raise minute ventilation.
• Treating lung volumes as fixed for every performer: age, sex, body size and training status all influence the values recorded.
• Misunderstanding: students believe residual volume can be exhaled with enough effort. Correction: it remains in the lungs after the most forceful expiration and cannot be breathed out.
• Misunderstanding: students include residual volume within vital capacity. Correction: vital capacity excludes residual volume, while total lung capacity includes it.
• Misunderstanding: students think a spirometer alone can measure residual volume. Correction: simple spirometry cannot record it because the air is not exhaled.
• Confusing ERV with tidal volume: tidal volume is the air moved in one quiet breath, whereas ERV is the extra air forcibly exhaled after that quiet breath.
• Confusing ERV with residual volume: residual volume is the air that cannot be exhaled at all, whereas ERV can be exhaled with effort.
• Thinking ERV is the total air exhaled in one maximal breath: that total is the vital capacity, which includes tidal volume, inspiratory reserve volume and ERV.
• Confusing IRV with tidal volume: tidal volume is the air moved in one quiet breath, whereas IRV is the extra air forcibly inhaled after that quiet breath.
• Confusing IRV with vital capacity: vital capacity is the total air exhaled after a maximal inhalation, which includes tidal volume, IRV and expiratory reserve volume.
• Thinking IRV is the maximum volume the lungs can hold: total lung capacity also includes residual volume, which cannot be exhaled.
• Confusing tidal volume with vital capacity: tidal volume is one resting breath, whereas vital capacity is the largest volume that can be forcibly expired after a maximal inspiration.
• Confusing tidal volume with minute ventilation: minute ventilation is the volume breathed per minute, calculated as tidal volume multiplied by breaths per minute.
• Treating tidal volume as a fixed maximum: it is a resting measure that rises with exercise, so it is not the greatest volume a person can move.
• Reading a spirometer trace without applying its calibration: the trace height must be converted to a volume using the scale, not reported as a raw distance.
• Confusing minute ventilation with tidal volume: tidal volume is one breath, while minute ventilation is the volume for a whole minute.
• Dividing instead of multiplying: minute ventilation is tidal volume multiplied by breathing frequency, not divided by it.
• Using the wrong time unit: the frequency must be breaths per minute so the answer is a volume per minute.
• Assuming minute ventilation is fixed at rest: it increases during exercise as both tidal volume and breathing frequency rise.
• Thinking oxygen and carbon dioxide diffuse in the same direction at both sites; correction: at alveoli oxygen enters blood and carbon dioxide leaves it, while at muscles oxygen leaves blood and carbon dioxide enters it.
• Believing diffusion needs active transport; correction: gas exchange is passive diffusion down partial pressure gradients.
• Assuming the gradient stays constant; correction: continued oxygen use in muscle and ventilation at alveoli maintain the gradients.
• Confusing partial pressure with concentration only; correction: partial pressure differences drive diffusion of gases.
• Thinking all oxygen is dissolved in plasma; correction: most oxygen is carried bound to haemoglobin as oxyhaemoglobin.
• Believing carbon dioxide is carried only as hydrogencarbonate; correction: it is also dissolved in plasma and bound to haemoglobin as carbaminohaemoglobin.
• Assuming oxygen and carbon dioxide always move in the same direction; correction: their directions reverse between alveoli and muscles.
• Confusing partial pressure with total pressure; correction: partial pressure of each gas drives its own diffusion.
• Thinking that oxygen diffuses from blood to alveoli: the correction is that oxygen diffuses from alveolar air into blood because alveolar partial pressure of oxygen is higher than that in deoxygenated blood.
• Confusing partial pressure with concentration or percentage: the correction is that partial pressure is the pressure exerted by one gas in a mixture, measured in kPa, and it is the gradient in partial pressure that drives diffusion.
• Believing that diffusion requires energy from ATP: the correction is that diffusion is passive and relies on the kinetic energy of gas molecules, so no ATP is used.
• Ignoring membrane thickness in Fick's law: the correction is that rate of diffusion is inversely proportional to thickness, so a thicker respiratory membrane slows gas exchange.
• Thinking that breathing is controlled only by the lungs: the correction is that the respiratory centres in the medulla oblongata and pons control breathing, with the lungs acting as effectors.
• Confusing the roles of central and peripheral chemoreceptors: the correction is that central chemoreceptors in the medulla are mainly sensitive to carbon dioxide and pH, while peripheral chemoreceptors in the aortic arch and carotid bodies respond to oxygen, carbon dioxide and pH.
• Believing that oxygen is the main stimulus for breathing at rest: the correction is that carbon dioxide is the primary chemical stimulus for ventilation at rest, with oxygen becoming more important during intense exercise.
• Ignoring neural input from proprioceptors and the motor cortex: the correction is that these provide feed-forward stimulation that increases ventilation at the onset of exercise.
• Thinking the sympathetic and parasympathetic nerves directly innervate respiratory muscles: they influence the RCC, which sends somatic impulses via the phrenic and intercostal nerves.
• Confusing the roles of the two divisions: the sympathetic division is active during exercise, while the parasympathetic division dominates at rest.
• Assuming breathing is only controlled consciously: the autonomic nervous system regulates it involuntarily based on the body's demands.
• Believing oxygen is the primary stimulus to breathe: carbon dioxide levels and the resulting pH changes are the main chemical drivers for ventilation.
• Stating that the autonomic nervous system directly innervates the diaphragm: the RCC sends somatic motor impulses via the phrenic and intercostal nerves.
• Forgetting to mention blood pH: an increase in carbon dioxide directly lowers blood pH, which is what the chemoreceptors detect.
• Thinking only oxygen is monitored: chemoreceptors respond strongly to rising carbon dioxide concentration and falling pH as well as falling oxygen concentration.
• Confusing proprioceptors with chemoreceptors: proprioceptors detect movement and limb position, not blood chemistry.
• Placing baroreceptors in the lungs: baroreceptors sit in blood vessel walls and detect blood pressure change.
• Assuming ventilation rises only after blood chemistry changes: proprioceptor input raises ventilation at the onset of exercise.
• Treating the three receptors as interchangeable: each has a different location and stimulus, so match chemoreceptors to chemistry, proprioceptors to movement and baroreceptors to blood pressure.
• Saying chemoreceptors detect only oxygen: rising carbon dioxide concentration and falling pH are also key stimuli.
• Placing proprioceptors in the brain: they are found in muscles, tendons and joints.
• Placing baroreceptors in the airways: they are found in blood vessel walls.
• Discussing lifestyle factors other than smoking: the specification explicitly limits this topic to the impact of smoking on the respiratory system.
• Believing smoking only affects the lungs: it also affects oxygen transport because carbon monoxide binds to haemoglobin.
• Vaguely stating smoking is bad for breathing without naming specific structures like cilia, alveoli, or airways.
• Saying smoking reduces the number of red blood cells: carbon monoxide binds haemoglobin, so the blood carries less oxygen even though red blood cell count is unchanged.
• Thinking cilia grow stronger to cope with smoke: cilia are paralysed and destroyed, so mucus clearance fails.
• Believing tar only discolours the lungs: it also destroys alveolar walls and reduces surface area for gaseous exchange.
• Confusing nicotine with carbon monoxide: nicotine raises heart rate and narrows vessels, while carbon monoxide reduces oxygen transport.
• Thinking all oxygen travels bound to haemoglobin: a small amount dissolves in plasma, though haemoglobin carries the majority.
• Believing oxygen is actively pumped onto haemoglobin: binding is passive and depends on partial pressure gradients.
• Assuming the dissociation curve is a straight line: it is S-shaped, so loading and unloading are not linear.
• Confusing myoglobin with haemoglobin: myoglobin stores oxygen in muscle and has a higher affinity, aiding uptake at the tissues.
• Students often think that breathing is controlled by the lungs themselves. Correction: Breathing is controlled by the medulla oblongata in the brainstem, which responds to chemical stimuli from chemoreceptors.
• Many believe that oxygen is carried primarily in the blood plasma. Correction: About 98% of oxygen is carried bound to haemoglobin in red blood cells; only 2% dissolves in plasma.
• Students sometimes confuse partial pressure with concentration. Correction: Partial pressure is the pressure exerted by a single gas in a mixture, and it drives diffusion; concentration is the amount of gas per unit volume.

1. 1Week 1: Learn the anatomy of the respiratory system using diagrams and labelling exercises. Focus on the pathway of air and the structure of alveoli.
2. 2Week 1: Study the mechanics of breathing at rest and during exercise. Create a table comparing inspiration and expiration, including muscle actions and pressure changes.
3. 3Week 2: Understand gas exchange and partial pressures. Practice explaining the diffusion of oxygen and carbon dioxide using correct terminology.
4. 4Week 2: Learn the neural and chemical control of breathing. Create a flowchart of the control pathway and test yourself on the roles of chemoreceptors.
5. 5Week 2: Review adaptations to training and complete past paper questions on the respiratory system, marking your answers against the mark scheme.

• 📋Short-answer questions (2-4 marks) asking for definitions or explanations of specific structures or processes, e.g., 'Define tidal volume' or 'Explain the role of the diaphragm during inspiration'.
• 📋Data analysis questions (4-6 marks) where you interpret spirometry traces or graphs of ventilation during exercise and explain the physiological reasons for the changes.
• 📋Extended writing questions (6-9 marks) requiring a detailed explanation of how the respiratory system responds to exercise or training, often linking to other systems.
• 📋Calculation questions (2-3 marks) involving VO2 max, pulmonary ventilation, or oxygen uptake, requiring correct formula application and units.