• Smoking causes?chronic obstructive lung disease?(COPD), coronary heart disease and?increased risks of several different types of cancer, including?lung cancer
• Chemicals in cigarettes include:
  • Tar?- a carcinogen (a substance that causes cancer)
  • Nicotine?- an addictive substance which also narrows blood vessels
  • Carbon monoxide?- reduces the oxygen-carrying capacity of the blood

   

Nicotine

• Nicotine?narrows blood vessels?leading to an?increased blood pressure
• It also increases?heart rate
• Both of these effects can cause blood clots to form in the arteries leading to?heart attack?or?stroke

Carbon monoxide

• Carbon monoxide?binds irreversibly to haemoglobin, reducing the capacity of blood to carry oxygen
• This puts more strain on the breathing system as?breathing frequency and depth need to increase?in order to get the same amount of oxygen into the blood
• It also puts more strain on the circulatory system to pump the blood faster around the body and increases the risk of?coronary heart disease and strokes

Tar

• Tar is a?carcinogen?and is linked to increased chances of cancerous cells developing in the lungs
• It also contributes to?COPD,?which occurs when?chronic bronchitis?and?emphysema?(two different diseases which are frequently linked to smoking) occur together
• Chronic bronchitis?is caused by?tar?which stimulates goblet cells and mucus glands to enlarge,?producing more mucus
  • It destroys?cilia?and?mucus?(containing dirt, bacteria and viruses)?builds up?blocking the smallest bronchioles and leading to infections
  • A?smoker's cough?is the attempt to move the mucus

   

• Emphysema?develops as a result of?frequent infection, phagocytes that enter the lungs release elastase, an enzyme that breaks down the elastic fibres in the alveoli
  • This means the?alveoli?become?less elastic and cannot stretch?so many burst
  • The breakdown of alveoli?reduces the surface area for gas exchange
  • As it progresses, patients become?breathless and wheezy?- they may need a constant supply of oxygen to stay alive

   

The breakdown of alveoli in emphysema reduces the surface area for gas exchange

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