9700 · 9.1
The gas exchange system flashcards
Revision flashcards for Cambridge 9700 The gas exchange system (syllabus 9.1). Flip, recall, then mark a real past-paper question.
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What is the function of the C-shaped cartilage rings in the trachea?
To provide support and prevent the trachea from collapsing during pressure changes associated with breathing, while allowing flexibility for swallowing.
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Name the two main cell types that make up the ciliated epithelium in the airways.
Goblet cells, which secrete mucus, and ciliated cells, which have cilia that beat to move the mucus upwards.
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What is the primary function of mucus in the respiratory tract?
To trap inhaled particles such as dust, pollen, and pathogens, preventing them from reaching the delicate alveoli.
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List four key adaptations of the alveoli for efficient gas exchange.
1. Large total surface area. 2. Thin walls (one-cell thick epithelium). 3. Rich blood supply from a dense capillary network. 4. Moist inner surface for gases to dissolve.
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What happens to the diaphragm and external intercostal muscles during inspiration (inhalation)?
The diaphragm contracts and flattens (moves down). The external intercostal muscles contract, pulling the rib cage up and out.
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How do the muscle actions during inspiration affect thoracic volume and pressure?
They increase the volume of the thoracic cavity, which decreases the pressure inside the lungs to below atmospheric pressure, causing air to flow in.
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Describe the muscle movements during quiet expiration (exhalation).
The diaphragm relaxes and domes upwards. The external intercostal muscles relax, allowing the rib cage to move down and in. This is a passive process driven by elastic recoil.
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Which additional muscles are involved in forced expiration?
The internal intercostal muscles (which contract to pull the rib cage down and in) and the abdominal muscles (which contract to push the diaphragm up).