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HUMAN GAS EXCHANGE (alveoli (blood passing next to alveoli has just…
HUMAN GAS EXCHANGE
alveoli
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blood passing next to alveoli has just returned to the lungs from body so has lots of CO2 and little O2.
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thin cell walls- one cell thick so gas doesnt have far to diffuse. walls are permeable so gases can diffuse easily
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smoking
damages walls inside alveloi, reducing SA - emphysema
emphysema is from continued coughing to clear tar from lungs. breaks down the divisions between alveoli so reduces SA.
tar damages cilia in lungs and trachea. cilia and mucus catch dust and bacteria before they reach the lungs. cilia also keep trachea clear by sweeping mucus towards mouth
when cilia are damaged, chest infections are more likely
tar irritates bronchi and bronchioles- more mucus produced- damaged cilia so can't clear mucus- smokers cough and chronic bronchitis
carbon monoxide reduces O2 blood can carry - heart rate increases- increase in blood pressure- damages artery walls- blood clots more likely- heart disease (attacks)
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thorax
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breathe in
diaphragm and intercostal muscles contract, thorax volume increases
breathe out
diaphragm and intercostal muscles relax, thorax volume decreases