Smoking

• Respiration


  A chemical reaction which releases energy from food
• Respiratory system


  Exchanges the gases which are involved in respiration
• Smoking can cause lung disease, heart disease and certain cancers
• Nicotine


  The addictive substance in tobacco
• Nicotine reaches the brain

  Creates a dependency so that smokers become addicted
• Effects of smoking on the air passages

  • Sticky mucus in the lungs traps pathogens
  • Mucus is normally swept out of the lungs by the cilia on the epithelial cells lining the trachea, bronchi and bronchioles
  • Cigarette smoke contains harmful chemicals that paralyse these cilia, leading to a build-up of mucus and a smoker's cough
  • Smoke irritates the bronchi, causing bronchitis
• Effects of smoking on the alveoli

  • Smoke damages the walls of the alveoli
  • The alveoli walls break down and join together, forming larger air spaces than normal
  • This reduces the ability of the blood to carry oxygen, putting a strain on the heart which increases the risk of developing coronary heart disease or strokes
• Carbon monoxide

  Combines with the haemoglobin in red blood cells, reducing the ability of the blood to carry oxygen, putting a strain on the heart which increases the risk of developing coronary heart disease or strokes
• Carcinogens

  Chemicals or other agents that cause cancer
• Smoking increases the risk of lung cancer, and cancer of the mouth, throat and oesophagus
• Tar is a sticky substance
• Tar stimulates mucus production
• Tar paralyses the cilia, preventing mucus from being swept away. Mucus contains microorganisms and dirt builds up
• Nicotine increases heart rate
• Damage to the alveoli walls and loss of elastic in the alveoli can lead to emphysema, a lung condition resulting in breathing difficulties.