Health, disease and cancer
Defining health
is a state of complete physical and mental wellbeing. Different types of disease can interact: a viral infection can trigger other illnesses, including some cancers; defects in the immune system can make a person more likely to get infectious diseases; and a severe physical illness can lead to mental health issues, such as depression.
Communicable vs non-communicable disease
are caused by pathogens (such as bacteria or viruses) and can spread between people — examples include measles and flu.
cannot be passed between people, and often develop over a long period of time — examples include cancer, cardiovascular disease, and type 2 diabetes.
Key terms
Risk factors
A is a lifestyle or environmental factor that increases the likelihood of developing a disease. Examples include: smoking (linked to lung disease, coronary heart disease and cancer), obesity (linked to type 2 diabetes and coronary heart disease), and excess alcohol (linked to liver disease). Genetics also plays a role in some non-communicable diseases.
Key terms
Benign vs malignant tumours
is caused by changes in cells that lead to uncontrolled cell division, forming a tumour.
grow but stay in one place, usually contained within a membrane, and do not invade other tissues — they are not usually dangerous.
invade neighbouring tissue and can spread to other parts of the body via the blood, forming secondary tumours elsewhere. Malignant tumours are cancerous and can be life-threatening.