IGCSE Biology Breathing and Gas Exchange

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  • Created by: Juliet
  • Created on: 26-03-13 18:26
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  • Breathing and Gas Exchange!
    • Inhalation
      • Lower Pressure in lungs than outside body
        • Air flows in
      • Volume of chest cavity expands
      • Diaphragm muscles contract
        • Diaphragm flattens
      • External intercostal muscles contract
        • Pulls ribcage up and out
    • Exhalation
      • Higher pressure in lungs than outside body
        • Pushes air out
      • Volume of chest cavity decreases
      • Diaphragm muscles relax
        • Diaphragm becomes dome shaped
      • Internal intercostal muscles contract
        • Pulls ribs down and in
    • Structure of human gas exchange
      • Nasal passaeges
        • Epiglottis
          • Oesophagus
            • Larynx
              • Trachea
                • Left Bronchus
                  • Bronchioles
                    • Alveoli
                      • Diaphram
                        • Ribs
                          • Internal intercostal muscles
                            • External Intercostal Muscles
                              • Pleural Membranes
                                • Pleural Fluid
                                  • Liquid filling pleural cavity acting as lubrication so surfaces of lungs do not stick to chest wall.
                                • Moist membrane forming airtight seal around lungs and separating thorax from lungs
                              • Push ribs up and out when  inhaling
                            • Pull ribs down and out when exhaling
                          • Bones that protect the vital organs
                        • Sheet of muscle with fibrous middle part which is domed
                        • helps make breathing movement and seporates thorax from the abdomen.
                      • Carry air to lungs
                    • Carry air to lungs
                  • Carries air to lungs
                • Tube with incomplete rings of  cartilage that carries air to lungs.
                • Lined with cells making mucus and cilia which move mucus away from lungs
              • Voice Box
            • Carries food to stomach
          • Stops Food getting into lungs when you swallow
        • Warm, Clean, Add moisture to air
    • Gas Exchanges In The Alveoli
      • Alveoli
        • Large Surface Area
        • Rich Blood supply
          • removes oxygen from and delivers carbon dioxide to the air in the alveoli
          • Maintains a steep diffusion gradient between the alveoli and the blood
        • Short diffusion distances between the air and the blood
      • Process
        • Blood pumped from the heart to the lungs
          • Passes through network of capillaries surrounding the alveoli
            • Carbon Dioxide diffuses from the blood into the air in the alveoli
              • Oxygen diffuses from the air in the lungs into the blood
                • Oxygenated blood travels back to the heart to be pumped around the body
                  • Oxygen dissolves in the layer of fluid lining the alveolus before it diffuses into the blood
    • Smoking And Health
      • Nicotine
        • Addictive substance found in tobacco
      • Carbon Monoxide
        • Reduces the amount of oxygen carried in the blood by bonding with the red blood cells' haemoglobin
      • Tar + Other Chemicals
        • Can cause lung cancer, bronchitis, emphysema + diseases of the heart and blood vessels.
      • Tobacco smoke
        • Cilia are destroyed so dirt and bacteria are not removed
        • Emphysema - walls of alveoli are damaged and break down to form large irregular air spaces which do not exchange gas efficiently
        • Lung Cancer - tar and other chemicals cause cells to mutate and form cancers in the lungs and throat
        • Carbon Monoxide binds to haemoglobin.In pregnant woman not enough oxygen in blood = not enough oxygen to fetus = still born
        • Affects Circulatory system and can increase risk of heart attacks and strokes
    • Breathing
      • For Cellular respiration to take place, your cells need a constant supply of oxygen for this to happen aerobically.
      • Cells need to have waste Carbon Dioxide removed




Great web site full of very useful information for IGCSE

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