Respiratory System: Structure, Function, and Response to Exercise

OCR

GCSE

Candidates must articulate the precise anatomical pathway of air and the mechanics of pulmonary ventilation, distinguishing between inspiration and expiration at rest versus during maximal exertion. Analysis must cover gaseous exchange at the alveoli and muscle tissue sites, utilizing the laws of diffusion and partial pressure gradients. Furthermore, responses require the interpretation of spirometer traces to evaluate tidal volume, minute ventilation, and vital capacity changes in response to varying intensities of physical activity.

Objectives

Exam Tips

Pitfalls

Key Terms

Mark Points

What You Need to Demonstrate

Key skills and knowledge for this topic

Award marks for the correct sequential pathway of air: nose/mouth, trachea, bronchi, bronchioles, alveoli.
Credit specific reference to the diaphragm flattening and intercostal muscles contracting to increase thoracic volume during inspiration.
Responses must explicitly state that gas exchange occurs via diffusion from an area of high partial pressure to low partial pressure.
For spirometer analysis, candidates must accurately distinguish between Tidal Volume (TV) and Vital Capacity (VC) on a graphical trace.
Award marks for linking increased breathing rate during exercise to the removal of carbon dioxide rather than just the intake of oxygen.

Example Examiner Feedback

Real feedback patterns examiners use when marking

"You have identified the structure correctly; now explain the mechanical process that causes the change in volume."
"Your definition of Tidal Volume is generic. Use the precise phrasing: 'volume of air inspired or expired per breath'."
"Link the features of the alveoli (one cell thick, moist walls) directly to the efficiency of diffusion for the athlete."
"When analysing the spirometer trace, ensure you are reading the axis values accurately to calculate the Minute Ventilation."

Marking Points

Key points examiners look for in your answers

Award marks for the correct sequential pathway of air: nose/mouth, trachea, bronchi, bronchioles, alveoli.
Credit specific reference to the diaphragm flattening and intercostal muscles contracting to increase thoracic volume during inspiration.
Responses must explicitly state that gas exchange occurs via diffusion from an area of high partial pressure to low partial pressure.
For spirometer analysis, candidates must accurately distinguish between Tidal Volume (TV) and Vital Capacity (VC) on a graphical trace.
Award marks for linking increased breathing rate during exercise to the removal of carbon dioxide rather than just the intake of oxygen.

Examiner Tips

Expert advice for maximising your marks

💡When describing mechanics, always follow the chain: Muscle Action -> Volume Change -> Pressure Change -> Air Movement.
💡Memorise the specific definitions of Tidal Volume, Expiratory Reserve Volume, and Residual Volume; vague descriptions are not credited.
💡In 6-mark analysis questions, ensure you link respiratory structural features (e.g., large surface area of alveoli) directly to their functional benefit for the athlete.

Common Mistakes

Pitfalls to avoid in your exam answers

Confusing the roles of the external and internal intercostal muscles during forced expiration.
Stating that the lungs 'suck' air in, rather than explaining that pressure decreases below atmospheric pressure causing air to rush in.
Failing to specify 'partial pressure' or 'concentration gradient' when describing gaseous exchange.
Misidentifying Residual Volume as the air left after a normal breath, rather than after maximal expiration.

Key Terminology

Essential terms to know

Anatomy and Mechanics of Pulmonary Ventilation

Gaseous Exchange and Partial Pressure Gradients

Spirometry and Lung Volume Interpretation

Physiological Adaptations to Aerobic Training

Likely Command Words

How questions on this topic are typically asked

Identify

Define

Explain

Analyse

Evaluate

Ready to test yourself?

Practice questions tailored to this topic