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B7: Non-communicable diseases (7.4: Diet, exercise, and disease (People…
B7: Non-communicable diseases
7.1: Non-communicable diseases
Cannot be passed from one person to another
Risk factors linked to an increased rate of disease
Age
Genetic make-up
Lifestyle e.g. diet, exercise, smoking etc.
Environmental factors e.g. ionising radiation, UV light from sun
Causal mechanisms
Sometimes scientists can see a link between 2 factors -
Correlation
- a rise in one factor may lead to a rise or fall in another for example
Once scientists notice a correlation they need to carry out more research to show there is a
causal mechanism
between the 2 factors
A causal mechanism explains how one factor affects another through a biological process
For some non-communicable diseases, it has not yet been possible to prove a causal mechanism
7.2: Cancer
Tumours
Sometimes a cell will change, due to mutations in the genetic material, and start to divide in an uncontrolled way
A benign tumour grows in one place - although it doesn't 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 tumour cells may enter the bloodstream and circulate to other parts of the body, forming secondary tumours
Causes of cancer
Genetic factors
Mutations in genes caused by carcinogens
Ionising radiation e.g. UV light
Virus infections e.g. HPV
Cancer can be treated with
Radiotherapy
Cancer cells are destroyed by targeted doses of radiation - this stops mitosis in the cancer cells but can also damage healthy cells
Chemotherapy
Chemicals are used to either stop the cancer cells dividing or to make them 'self-destruct'
7.3: Smoking and the risk of disease
The smoke from cigarettes contains about 4000 chemicals - about 150 of these have been linked to disease
Tobacco smoke contains
Nictotine
Addictive substance
Carbon monoxide
A toxic gas, which replaces oxygen in red blood cells
Tar
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
Problems caused by smoking
Blood carries less oxygen around the body because of carbon monoxide attaching to red blood cells - leading to breathlessness
If a pregnant woman smokes, her baby will also receive less oxygen - leading to premature births, low birth weight, or stillbirths
Mucus containing dirt and pathogens builds 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
Cardiovascular disease
Blood vessels in the skin narrow
Nicotine increases the heart rate
Some chemicals damage the lining of the blood vessels, increasing the risk of clots
Other chemicals cause and increase in blood pressure
A combination of these factors leads to heart attacks and strokes
7.4: Diet, exercise, and disease
Your weight and the amount you exercise can affect your risk of developing various diseases
Eating too much food for your energy needs will make you overweight and possibly obese
Obesity can lead to type 2 diabetes, high blood pressure, or heart disease
People who exercise regularly will have
Bigger muscles
Bigger hearts
Bigger lungs
Regular exercise reduces your risk of developing cardiovascular disease
By lowering blood cholesterol 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
7.5: Alcohol and other carcinogens
Alcohol
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
Alcohol (ethanol) is a commonly used social drug - it is very addictive
Long-term drinking can also lead to liver cancer
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 in the liver
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
Ionising radiation
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