The Breathing System (Cambridge International IGCSE Biology)
Exam board Cambridge International · IGCSEUpdated 2026-09-02
Spec point —
11.1.2· Identify in diagrams and images the following parts of the breathing system: lungs, diaphragm, ribs, intercostal muscles, larynx, trachea, bronchi, bronchioles, alveoli and associated capillaries
The breathing system
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The breathing system includes the following parts:
- the lungs
- diaphragm
- ribs
- intercostal muscles
- larynx
- trachea
- bronchi
- bronchioles
- alveoli and associated capillaries
Structures in the human breathing system
The internal and external intercostal muscles
Structures of the breathing system table
| Structure | Description |
|---|---|
| Ribs | Bone structure that protects internal organs such as the lungs |
| Intercostal muscle | Muscles between the ribs which control their movement, causing inhalation and exhalation |
| Diaphragm | Sheet of connective tissue and muscle at the bottom of the thorax that helps change the volume of the thorax to allow inhalation and exhalation |
| Trachea | Windpipe that connects the mouth and nose to the bronchi, allowing air to pass into the lungs |
| Larynx | Also known as the voice box; when air passes across here, we are able to make sounds |
| Bronchi (singular: bronchus) | Large tubes branching off the trachea, with one for each lung |
| Bronchioles | Bronchi split to form smaller tubes called bronchioles in the lungs, connected to alveoli |
| Alveoli | Tiny air sacs where gas exchange takes place |
Exam Hint You should be able to identify in diagrams and images the parts of the breathing system listed above, so make sure you study them.
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