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Mammalian GES
OCR Yr12 Biology A 3.1.2 Mammalian gaseous exchange system
Question | Answer |
---|---|
Alveoli | Tiny folds of lung epithelium. Increase surface area. Found in clusters at the end of the smallest bronchioles. |
Bronchi | Branching from trachea, smaller airways leading into each lung. Supported by rings of cartilage which prevent collapse during inspiration. |
Diaphragm | Layer of muscle beneath the lungs. During inspiration it contracts, flattens and pushes digestive organs downwards. During expiration it relaxes and is pushed upwards by digestive organs. |
External intercostal muscles | Muscles between ribs. Contract during inspiration raising ribs Relax during expiration, lowering them. |
Internal intercostal muscles | Can contract during expiration to help push air out more forcefully. During exercise, coughing or sneezing. |
Trachea | Main airway from back of the mouth to the lungs. Supported by C-shaped rings of cartilage. Prevents collapse during inspiration. Allows flexibility for food to move down the oesophagus. |
Bronchioles | Much narrower airways leading into the lungs from the bronchi. Larger ones with cartilage, smaller without. Walls are mostly smooth muscle and elastic fibres. |
Ventilation | The refreshing of air in the lungs to maintain a high oxygen and low carbon dioxide concentration compared with the blood. Process brought about by the action of the intercostal muscles and diaphragm. |