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Smoking and Disease

Cardiovascular System
1. Atherosclerosis
  1. When damage occurs to the lining of an artery, white blood cells move into the area. Over time, WBCs, lipids and connective tissue build up and harden to form a hard plaque - an atheroma.
  2. The atheroma partially blocks the lumen of the artery and restricts blood flow.
  3. Atherosclerosis is the hardening of arteries due to the formation of atheromas.
  4. Cigarette smoke contains nicotine which causes an increase in blood pressure and therefore causes increased damage to the arteries.
2. Coronary Heart Disease (CHD)
  1. This is when the coronary arteries have lots of atheromas in them, restricting blood flow to the heart.
  2. A reduction in blood flow reduces the amount of oxygen an area of the heart gets. This causes chest pain (angina).
  3. Smoking increases this risk because the CO irreversibly combines with the haemoglobin, reducing the amount of oxygen transported in the blood, and therefore reducing the amount of oxygen available to the tissues and the heart muscle cells.
  4. Nicotine in cigarette smoke makes platelets sticky so they increase the chance of clots forming. If this happens in the coronary arteries, it can cause a heart attack.
  5. The presence of atheromas also increases the risk of clots forming.
3. Stroke
  1. A stroke is a rapid loss of brain function due to disruption in the blood supply to the brain.
  2. This can be caused by a blood clot in an artery leading to the brain which reduces the blood supply and therefore oxygen that can reach the brain.
  3. Nicotine increases the risk because it increases the chance of blood clots.
  4. CO increases the risk because it reduces the amount of oxygen that can get to the brain by combining with haemoglobin.
Gas Exchange System
1. Lung Cancer
  1. Carcinogens in cigarette smoke can cause mutations in the DNA of lung cells which could lead to uncontrolled cell growth and the form of a malignant .tumour
  2. These tumours grow uncontrollably, blocking air flow to areas of the lung.
  3. This decreases gas exchange and leads to shortness of breath as the body cannot take in enough oxygen.
  4. The tumour uses lots of nutrients and energy to grow, which causes weight loss.
2. Chronic Bronchitis
  1. This is inflammation of the lungs.
  2. Cigarette smoke damages the cilia and causes the goblet cells to secrete more mucus and it accumulates in the lungs and causes coughing to try and remove it.
  3. Microorganisms multiply in the mucus and cause lung infections that lead to inflammation and decreases gas exchange.
  4. COPD is a group of diseases that involve permanent airflow reduction. Chronic Bronchitis is a type of COPD.
3. Emphysema
  1. A lung disease caused by smoking/prolonged exposure to air pollution where foreign particles get trapped in the alveoli.
  2. This causes inflammation which encourages the presence of phagocytes. They produce an enzyme which breaks down the elastic wall of the alveoli, destroying their walls and elasticity.
  3. This reduces the surface area of the lungs, decreasing the rate of gaseous exchange.
  4. Symptoms include: shortness of breath and wheezing.
Interpreting Evidence
1. Method
  1. Sample size - large/small? The bigger it is, the more reliable the results.
  2. Type of study? E.g. questionnaires leave room for people to lie.
  3. People used? Depending on the people, bias could occur.
  4. Variables should be as controlled as possible, i.e. all the participants should be matched in some way.

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Smoking and Disease

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