Lung parts functions

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  • Mammalian lungs adaptations
    • Epithelial tissue line the trachea and the bronchi
      • Made of ciliated cell and goblet cells
        • sitting on a basement membrane
          • contains fibres made from proteins
        • Each cilium contains microtubules which slide past each other
          • this causes the cilium to bend
        • Goblet cells secrete mucus
          • contains glycoproteins in mucus
            • the long sugar chains make the mucus slimy and sticky
          • forms a complete protective covering over epithelium
          • stops the cells from drying out
            • traps particles from the air
              • this prevents them reaching the alveoli and causing damage
    • Cartilage
      • tough tissue
        • supports the walls of trachea and bronchi
      • cartilage does not reach to/past the bronchioles
      • more flexible than bone
        • helps to hold the tubes open as the air pressure inside them changes
          • In trachea they are c-shaped rings
            • In bronchi- they are more of an irregular pattern
    • Smooth muscle
      • In the walls of the trachea, bronchi and bronchioles
      • contracts slowly and steadily
        • can remain contracted for long periods of time
      • involuntary mucle
        • when it contracts it narrows the airways
          • useful to change the diameter of small bronchioles
            • they can be made wider when a person is exercising= needs air in and out more rapidly
      • they can also react to drugs
        • beta agonists can be inhaled to help make muscles relax
    • Elastic fibres
      • found in all airways
        • Important especially in alveoli-
          • breathing in- alveoli expand and stretch the elastic fibres
          • breathing out= the fibres RECOIL
            • This helps to decrease the volume inside the lungs and forces air out


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