B7

Non-Communicable diseases cannot be passed from one person to another.

Risk factors that are linked to an increased rate of disease include:

• Age
• Genetic Make-Up
• Aspects of lifestyle such as diet, obesity, level of exercise, and inhaling carcinogens in tobacco smoke
• Environmental factors such as ionising radiation, UV light from the sun, and second-hand tobacco smoke.

• Sometimes scientists can see a link between two factors. A rise in one factor might lead to a rise or fall in the other.
  • Example, scientists noticed that the more cigarettes a person smoked, the more chance they would have of developing lung cancer or cardiovascular disease. The scientists saw a correlation between smoking and lung cancer.
• Once scientists notice a correlation they need to carry out more research to show there is a casual mechanism between the two factors. A casual mechanism explains how one factor influences another through a biological process.
• Scientists have shown that the casual mechanism of increased rates of lung cancer from smoking is the action of the carcinogens in tobacco smoke on cells in the lungs.

Tumours: The process of mitosis is normally well controlled when cells divide. However, sometimes a cell will change, due to mutations in the genetic material, and start to divide in an uncontrolled way.

• A mass of abnormally growing cells is called a tumour.
• A benign tumour grows in one place. Although it does not invade other tissues, it can be dangerous if it grows in tissue such as the brain and compresses it.
• Malignant tumour cells can spread to healthy tissue. Malignant tumours are cancer.
• Some malignant cells may enter the bloodstream and circulate to other parts of the body, forming secondary tumours.

Causes of cancer include:

• Genetic factors
• Mutations in genes caused by carcinogens
• Ionising radiation (e.g. UV light causing skin cancers)
• Virus infections, such as HPV, which causes cervical cancer

Cancer can be treated with radiotherapy and chemotherapy.

The smoke from cigarettes contains about 4000 chemicals. About 150 of these chemicals have been linked to disease.

Tobacco smoke contains:

• Nicotine, which is the addictive substance in the smoke.
• Carbon monoxide, a toxic gas, which replaces oxygen in red blood cells.
• Tar, which is a sticky black substance that accumulates in the lungs and is also carcinogenic.
• Chemicals that anaesthetise the cilia in the airways, preventing them from wafting up the mucus.

Smoking can cause cardiovascular disease including coronary heart disease, lung cancer, and lung diseases such as bronchitis and COPD.

A fetus exposed to smoke has a restricted oxygen supply, which can lead to premature birth, low birth weight and even stillbirth.

• The blood carries less oxygen around the body because of carbon monoxide attatching to red blood cells. This can lead to breathlessness.
• If a pregnant woman smokes, her baby will also recieve less oxygen, leading to premature births, low birth weights or stillbirths.
• Mucus containing dirt and pathogens build up in the airways because it is not removed. This leads to infection and coughing.
• Tar and other chemicals lead to bronchitis because they inflame the bronchi.
• Tar can damage the alveoli, causing chronic obstructive pulmonary disease (COPD), which in turn leads to severe breathlessness and death.
• Tar causes other cancers of the respiratory system including cancers of the throat, larynx, and trachea.
• A casual link has been shown between smoking and cardiovascular disease. The blood vessels in the skin narrow. Nicotine increases the heart rate. Some chemicals damage the lining of blood vessels, increasing the risk of clots, and other chemicals cause an increase in blood pressure. A combination of these factors lead to heart attacks and strokes.

Diet affects your risk of developing cardiovascular and other diseases directly through chloestrol levels and indirectly though obesity.

Your weight and the amount of exercise you do can affect your risk of developing various diseases:

• Eating too much food for your energy needs will make you overweight and possible obese.
• Obesity can lead to type 2 diabetes, high blood pressure and heart disease.
• People who exercise regularly have bigger muscles, bigger hearts and bigger lungs than those who do not exercise.
• Regular exercise reduces your risk of developing cardiovascular diease.
  • By lowering blood cholestrol levels and reducing fatty deposits in the blood vessels.
  • By building muscle tissue, which increases your metabolic rate and means you are less likely to be overweight.
  • By improving the blood supply to the heart so the heart is fitter.

Alcohol can damage the liver and cause cirrhosis and liver cancer.

Alcohol (ethanol) is acommonly used social drug. Alcohol is very addictive.

• Alcohol enters the bloodstream and reaches all parts of the body including the brain and liver.
• Large amounts of alcohol affect the nervous system, slowing reactions, reflexes and thought processes. Very large amounts can cause death.
• The liver breaks down the alcohol. However, over a long period of heavy drinking the liver becomes damaged and the person may have cirrhosis caused by scar tissue on the liver. Long-term drinking can also lead to liver cancer.
• Long-term alcohol abuse can also cause damage to the brain.
• If a pregnant woman drinks alcohol it can pass across the placenta to the fetus. The alcohol can cause physical problems such as facial deformities and heart problems. After birth the baby may have developmental and learning problems. This is called fetal alcohol syndrome.

Radioactive materials are a source of ionising radiation and are carcinogenic.

• Radiation penetrates the cells and damages the chromosomes, leading to mutations in the DNA.
• Sources of radiation include UV light from the sun, radon gas, medical and dental x-rays, and accidents at nuclear power stations.