Non-communicable diseases · GCSE Biology

Health and disease

Health is a state of physical and mental wellbeing.
Diseases, both communicable and non-communicable, are major causes of ill health. Diet, stress and life situations also affect health.
Communicable diseases can spread between people; non-communicable diseases cannot.

Defects in the immune system make a person more likely to catch infectious diseases.
Some viruses living in cells can trigger cancer; for example, some types of HPV can cause cervical cancer.
Immune reactions to a pathogen can trigger allergies such as skin rashes or asthma.
Severe physical ill health can lead to mental illness such as depression.

A risk factor is linked to an increased rate of a disease. It can be an aspect of lifestyle or a substance in the body or environment.
Diet, smoking and lack of exercise increase the risk of cardiovascular disease.
Obesity is a risk factor for Type 2 diabetes.
Alcohol damages the liver and affects brain function. Smoking causes lung disease and lung cancer.
Smoking and drinking alcohol during pregnancy can harm the unborn baby.
Carcinogens, including ionising radiation, are risk factors for cancer.

Many diseases are caused by several risk factors working together.
A correlation between a factor and a disease does not prove the factor causes it; scientists need to find a mechanism.
Non-communicable diseases have human costs (suffering, early death) and financial costs to individuals, the NHS and the economy, at local, national and global levels.

Cancer is the result of changes in cells that lead to uncontrolled growth and division.
Benign tumours are growths of abnormal cells contained in one area, usually within a membrane. They do not invade other parts of the body.
Malignant tumours are cancers. They invade neighbouring tissues and spread in the blood to other parts of the body, forming secondary tumours.
Lifestyle risk factors (such as smoking, UV exposure and obesity) and genetic risk factors (such as inherited faulty genes) are linked to some cancers.

Health: A state of physical and mental wellbeing.
Non-communicable disease: A disease that cannot be passed from one person to another, such as heart disease.
Communicable disease: A disease caused by a pathogen that can spread between people or animals.
Risk factor: Something linked to an increased chance of developing a disease.
Carcinogen: A substance or agent, such as tobacco smoke or ionising radiation, that can cause cancer.
Cancer: A disease caused by changes in cells that lead to uncontrolled growth and division.
Benign tumour: A growth of abnormal cells that stays in one area and does not spread.
Malignant tumour: A cancerous growth that invades tissues and can spread to form secondary tumours.
Correlation: A link between two variables; it does not prove that one causes the other.
Cardiovascular disease: A disease of the heart or blood vessels.