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  • Smoking
    • Cigarette smokes contains over 4000 chemicals. Harmful substances such as tar (carcinogens), carbon monoxide and nicotine.
      • Carcinogens - chemicals that cause cancer.
      • Nicotine -  chemical in cigarette smoke that causes addiction.
        • Mimics the action of transmitter substances at the synapses between nerves - smoker feels more alert as nervous system is more sensitive.
          • Causes the release of adrenaline - increased heart rate and breathing rate, constriction of arterioles leading to the extremities of the body - reduces blood flow and oxygen delivery.
      • Carbon monoxide - enters RBCs and combines with haemoglobin - reduces oxygen carrying capacity of the blood - when exercising smokers will feel this - body will detect lower level of oxygen - heart rate rises.
    • Tar
      • Short term effects: tar settles on lining of airways and alveoli - increases diffusion distance, chemicals can cause an allergic reaction - smooth muscle contracts - lumen gets smaller, stimulates goblet cells and mucus-secreting glands enlarge and release mucus that collects in airways, bacteria and viruses in mucus - susceptible to infection.
      • Longer term effects: Smoker's cough to shift bacteria as clearing the airways is needed - cough can damage delicate linings of airways.
        • Infections attract white blood cells - enzymes digest part of the lungs to pass into air spaces - loss of elasticity in alveolus wall - cannot recoil to push air out.
      • Contains carcinogens. Enters cells, affects genetic material. If genes are affected - uncontrolled cell division.


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