Lungs

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  • Created by: emma
  • Created on: 06-03-14 18:40
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  • Lungs
    • Structure
      • Trachea
      • Brochi
      • Brochiole
      • Alveoli
      • Diaphragm
    • Breathing
      • Inhalation
        • Rib muscles contract expanding rib cage
          • diaphragm contracts and moves down
            • Lung volume increases
              • Pressure in lung less than outside
                • Air moves into lungs
      • Exhalation
        • Rib muscles relax
          • Diaphragm relaxes
            • Lung volume decreases
              • Pressure in lungs greater than outside
                • Air move out of lungs
      • Pulmonary ventilation= ventilation rate * tidal volume
    • Alveoli
      • Many alveoli with many capillaries
        • Provides a large surface area
      • Ventilation of air in lungs and circulation of blood
        • Maintains concentration gradient
      • Alveolar epithelium is thin
        • Short diffusion distance
    • Disease
      • Tuberculosis
        • Bacteria transmitted in droplets
          • Engulfed by phagocytes
            • Encased in tubercle
              • Lays dormant
                • If immunosuppressed bacteria activate
                  • Bacteria destroy alveoli
                    • scar tissue forms (increase diffusion distance)
      • Fibrosis
        • Damage to epithelium and scarring
          • Reduces rate of diffusion as diffusion distance increases
          • Reduces elasticity of lungs so breathing less efficient (concentration gradient)
      • Asthma
        • Allergic reaction triggers white blood cells to release inflammatory chemicals
          • Inflamed bronchial tube reduces air flow through
            • Effects concentration gradient
      • Emphysema
        • Irritants e.g smoking
          • Elastic tissue becomes damaged
            • Less air leaves lungs (concentration gradient)
            • Less oxygen reaches tissue for respiration
          • Alveolar wall breaks down and fills with fluid
            • Increased surface area for diffusion

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