The Effects of Smoking
- Smoking leads to emphysema and an increased risk of several different types of cancer, including lung cancer
- There are strong links between cigarette smoking and lung cancer and emphysema
- The majority of cases of lung cancer are caused by smoking
Graph showing a correlation between numbers of adults who smoke and lung cancer rates over time
- Note that as the general trend shows that as the number of adults who smoke decreases, so does the lung cancer rates a few years later (as cancer takes some time to develop)
- The trend in the rate of developing lung cancer for women has been increasing, while in men it is decreasing
- This is because the number of female smokers – unlike men – continued to increase in the 1950s and 1960s before starting to fall
- As cancer takes some years to develop, a fall in female rates of lung cancer is likely to occur later
- Chemicals in cigarettes include:
- Tar - a carcinogen (a substance that causes cancer)
- Nicotine - an addictive substance which also narrows blood vessels
Tar
- Tar is a carcinogen and is linked to increased chances of cancerous cells developing in the lungs
- It also contributes to the lung disease emphysema
Nicotine
- Nicotine is addictive
- It narrows blood vessels leading to 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
Lung cancer
- Tumours can develop in the respiratory system which is a consequence of the chemicals found in cigarette smoke
- Tumours can interfere with the normal working of the lungs
- Symptoms of lung cancer include:
- Coughing up blood
- A persistent cough
- Coughing an increased amount of mucus
- Back or shoulder pain
- Wheezing and breathing difficulties
- Sudden weight loss
Emphysema
- Emphysema is a lung disease that can develop as a result of the chemicals found in cigarette smoke
- Frequent infections can develop in the lungs of smokers which results in phagocytes (a type of white blood cell) being attracted to the tissues of the lungs
- Phagocytes release enzymes that damage the alveolar walls which create large air spaces in the alveoli resulting in a smaller surface area for gas exchange
- The consequences of this are breathlessness and wheezy breathing
- Once the disease progresses, people often need a constant supply of oxygen to stay alive
Emphysema diagram
The breakdown of alveoli in emphysema reduces the surface area for gas exchange
Cilia and mucus
- The effects of smoking also damage the cilia cells and the mucus that line the airways of the respiratory system
- The chemicals in cigarette smoke paralyse cilia which prevents them from working
- The small particles found in cigarette smoke clog the mucus which prevents it from moving up and out of the airways instead it builds up blocking the smallest bronchioles
- A smoker's cough is the attempt to move the mucus but it damages the epithelia resulting in scar tissue, which narrows the airways and makes breathing difficult
- Dirt and pathogens contained within the mucus are not removed from the airways so frequent infections of the respiratory system can occur
