gas exchange in humans

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  • Gas exchange in humans
    • structure of the thorax
      • ribs
        • protect the organs behind the ribs
      • intercostal muscles
        • helps with breathing
          • ribs
            • protect the organs behind the ribs
      • diaphragm
        • muscular and below the lungs
          • helps with breathing
        • trachea
          • branches into two...
            • bronchi
              • structure of the thorax
                • intercostal muscles
                  • diaphragm
                    • muscular and below the lungs
                    • trachea
                      • branches into two...
                        • bronchi
                          • split into smaller branches...
                            • bronchioles
                              • these end in microscopic air sacs called...
                                • ALVEOLI
                                  • adaptations
                                    • thin walls, one cell thick
                                      • short diffusion distance
                                    • large surface: volume ratio due to the shape
                                    • capillaries are very close to alveoli
                                      • short diffusion distance
                                  • alviolus
                      • cartilage rings keep the thorax open
                    • LUNGS
                      • TISSUE WITH ELASTIC FIBRES TO STRETCH AND RECOIL
                        • PROTEIN CALLED ELASTIN
                        • HELPS TO EXPEL AIR
                  • split into smaller branches...
                    • bronchioles
                      • these end in microscopic air sacs called...
                        • ALVEOLI
                          • adaptations
                            • thin walls, one cell thick
                              • short diffusion distance
                            • large surface: volume ratio due to the shape
                            • capillaries are very close to alveoli
                              • short diffusion distance
                          • alviolus
              • cartilage rings keep the thorax open
            • LUNGS
              • TISSUE WITH ELASTIC FIBRES TO STRETCH AND RECOIL
                • PROTEIN CALLED ELASTIN
                • HELPS TO EXPEL AIR
          • ventilation
            • breathing in
              • external intercostal muscles CONTRACT
                • pulling the rib cage upwards and outwards
              • diaphragm CONTRACTS
                • pulling downwards
              • lung volume is INCREASED
              • pressure inside the lungs DECREASES
              • AIR IS SUCKED IN
            • breathing out
              • external intercostal mucles RELAX
                • ribcage is pulled downwards and inwards
              • diaphragm RELAXES
                • moving upwards
              • lung volume DECREASES
              • pressure inside the lungs INCREASES
              • AIR IS FORCED OUT
          • gas exchange
            • in the lungs gas exchange takes place in the alveoli
            • Limewater turns cloudy in the presence of carbon dioxide, so it can be used to show the differences between inhaled air and exhaled air. The limewater immediately turns cloudy on contact with exhaled air.
            • gas exchange takes place in order to get oxygen from the air into the lungs. It then travels in the blood stream to cells, where it is used in repiration
          • smoking
            • Smoke damages the walls of the alveoli. The alveoli walls break down and join together, forming larger air spaces than normal. This reduces the efficiency of gas exchange
              • so people with the lung disease emphysema carry less oxygen in their blood and find even mild exercise difficult.
            • Carcinogens are substances that cause cancer. Tobacco smoke contains many carcinogens, including tar. Smoking increases the risk of lung cancer
            • carbon monoxide, CO, combines with the haemoglobin in red blood cells. This reduces the ability of the blood to carry oxygen, putting strain on the circulatory system
              • increases the risk of coronary heart disease
                • strokes

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