How does the respiratory system work, and what happens in a disorder such as asthma?
The structure and function of the respiratory system: the airways, lungs and gas exchange, the mechanism of breathing, and a physiological disorder of the system (asthma or chronic obstructive pulmonary disease) including its causes, effects and management.
A CCEA A2 2 answer on the respiratory system: the structure of the airways and lungs, gas exchange at the alveoli, the mechanism of breathing, and a physiological disorder (asthma, with reference to chronic obstructive pulmonary disease), including its causes, signs and symptoms and management.
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What this dot point is asking
CCEA wants you to describe the structure and function of the respiratory system (the airways, lungs, gas exchange and the mechanism of breathing) and to explain a physiological disorder of the system. The most commonly taught disorder is asthma (with reference to chronic obstructive pulmonary disease, COPD): its causes, effects and management.
Structure and function of the respiratory system
Air follows a clear pathway: nose or mouth, trachea (windpipe), two bronchi (one to each lung), smaller bronchioles, ending in alveoli (tiny air sacs). The alveoli are the gas-exchange surface and are well adapted: a large surface area, walls one cell thick (a short diffusion distance), a rich capillary supply, and a moist lining, all of which make diffusion efficient.
The mechanism of breathing and gas exchange
Gas exchange depends on diffusion down concentration gradients, which is why the alveoli's adaptations matter so much. Anything that reduces the surface area (as in COPD) or narrows the airways (as in asthma) reduces the efficiency of breathing and gas exchange.
Asthma
Triggers include allergens (pollen, dust mites, animal fur), cold air, exercise, smoke, air pollution and respiratory infections. Symptoms are wheezing, breathlessness, coughing and a tight chest, which can be frightening and, in a severe attack, life-threatening. (For contrast, COPD is a usually irreversible narrowing and damage of the airways and alveoli, strongly linked to smoking, causing progressive breathlessness.)
Management
Asthma is managed by avoiding triggers, using a reliever inhaler (a bronchodilator) to open the airways when symptoms occur, and a preventer inhaler (a corticosteroid) used regularly to reduce inflammation. Peak flow monitoring tracks lung function over time, and an asthma action plan sets out what to do as symptoms change. As with coronary heart disease, management combines the individual's self-care with medical support.
Try this
Q1. State the correct pathway of air from the mouth to the alveoli. [3 marks]
- Cue. Mouth (or nose), trachea, bronchi, bronchioles, alveoli.
Q2. Name two adaptations of the alveoli for gas exchange. [2 marks]
- Cue. A large surface area, walls one cell thick, a rich capillary supply, a moist lining (any two).
Q3. Explain the difference between a reliever and a preventer inhaler. [2 marks]
- Cue. A reliever opens the airways during symptoms; a preventer is taken regularly to reduce inflammation and prevent attacks.
Exam-style practice questions
Practice questions written in the style of CCEA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
CCEA A2 2 20186 marksDescribe the structure of the respiratory system and explain how gas exchange occurs in the alveoli.Show worked answer →
A 6-mark answer needs the pathway of air and the features of the alveoli that aid exchange.
Structure and pathway: air enters through the nose or mouth, passes down the trachea (windpipe), which branches into two bronchi (one to each lung), then into smaller bronchioles, ending in tiny air sacs called alveoli. The lungs are protected by the ribs and ventilated by the diaphragm and intercostal muscles.
Gas exchange: at the alveoli, oxygen diffuses from the air in the alveolus into the blood in the surrounding capillaries, and carbon dioxide diffuses the other way. The alveoli are adapted for this: a very large surface area, walls one cell thick (a short diffusion distance), a rich capillary supply, and a moist lining.
Markers reward the correct air pathway, the alveoli as the exchange surface, and the adaptations that make diffusion efficient.
CCEA A2 2 20228 marksExplain the causes and effects of asthma, and describe how it is managed.Show worked answer →
An 8-mark answer needs the mechanism, triggers, effects and management.
Cause and mechanism: asthma is a long-term condition in which the airways (bronchi and bronchioles) become inflamed and narrowed. In an attack the muscles around the airways tighten (bronchoconstriction), the lining swells and extra mucus is produced, so the airways narrow further.
Triggers: allergens (pollen, dust mites, animal fur), cold air, exercise, smoke, air pollution and respiratory infections.
Effects: wheezing, breathlessness, coughing, a tight chest and difficulty breathing, which can be frightening and, in a severe attack, life-threatening.
Management: avoiding triggers, a reliever inhaler (bronchodilator) to open the airways during symptoms, and a preventer inhaler (corticosteroid) used regularly to reduce inflammation. Peak flow monitoring tracks lung function and an asthma action plan guides what to do.
Markers reward the inflammation and bronchoconstriction mechanism, named triggers, the symptoms, and reliever and preventer management.
Related dot points
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Sources & how we know this
- CCEA GCE Health and Social Care specification — CCEA (2016)