Lungs and Lung Disease

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  • Lungs and Lung Disease
    • Mammalian Lungs
      • Located inside the body because
        • they would lose water and dry and dry
        • air is not dense enough to hold these structures
      • Parts of the lungs
        • The alveoli are minute air sacs at the end of bronchioles. Contains collagen and elastic fibres. This allows the alveoli to expand and spring back.
        • The trachea is an airway made of cartilage-this prevents the trachea from collapsing in on itself.
          • Lined with ciliated epithelium and goblet cells. The goblet cells produce mucus ant the cilia move the mucus to the stomach.
        • The Bronchi are two versions of the trachea-containing goblet and ciliated epithelium cells.
        • The lungs are a pair of structures that contain bronchioles and alveoli.
        • The bronchioles are a sub division of the bronchi. They contract to control the flow of gaseous substances in the alveoli.
    • Pulmonary ventilation
      • Pulmonary ventilation=tidal volume x ventilation rate
        • tidal volume is the volume of air taken in in a normal breath. Ventilation rate is how many breaths taken in one minute.
    • Alveoli
      • How is the alveoli adapted for its function?
        • Partially permeable
        • Very thin
        • Moist
        • Large surface area:volume
        • Good blood supply
      • Fick's Law
        • diffusion is proportional to: surface area x difference in concentration/ length of diffusion path
        • Alveoli are thin so a there is a small length of diffusion path etc.
      • Role of the alveoli
        • Diffusion happens fast because:
          • large surface area of capillaries and alveoli
          • The walls are very thin
          • ventilation circulation happens at the same time.
          • The red blood cells are pushed against the alveoli
          • concentration gradients are maintained
          • Red blood cells are slowed to allow more time for diffusion
    • Lung diseases
      • Pulmonary Tuberculosis
        • Symptoms include tiredness, persistent cough and loss of appetite.
        • Course of infection
          • The bacteria grow and divide where there is a lot of oxygen
            • White blood cells engulf the bacteria
              • This leads to inflammation of the lymph nodes
                • Usually controlled within a few weeks, but it can re emerge in a few years
                  • The bacteria destroy lung tissue
                    • The sufferer coughs up damaged lung tissue
      • Pulmonary Fibrosis
        • when scars on the epithelium of the lungs thicken.
          • Breathing is made harder due to the lungs having less surface area
          • Symptoms
            • Pain in chest due to pressure
            • Dry cough
            • Weakness from reduced intake of oxygen
            • Shortness of breath due to less space in the lungs
      • Asthma
        • An allergen causes the white blood cells to secrete a chemical called histamine
          • The lining becomes inflamed
            • More mucus is produced
              • Fluid enters the airways
                • The bronchioles constrict
        • Symptoms
          • A tight chest
          • A wheezing sound when breathing
          • Coughing
          • Difficulty in breathing
      • Emphysema
        • Where the elastin has been scarred. This elastic becomes permanently stretched so air isn't forced out.
        • Symptoms
          • Chronic cough
          • Blue skin colour
          • Shortness of breath

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