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Biology · Health, Disease and Cancer

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Biology · AQA Paper 1

Health, Disease and Cancer

Health and Disease

Health is physical and mental well-being, and diseases of different types often affect each other.

  • Health The state of physical and mental well-being.
  • Communicable disease A disease caused by a pathogen that can be passed from one organism to another.
  • Non-communicable disease A disease that is not caused by a pathogen and cannot be passed on.
A diagram with health in the centre and four ways that diseases interact: a weak immune system leading to infections, viruses triggering cancer, immune reactions causing allergies, and physical illness causing mental illness.
Different types of disease can make each other more likely.

Risk Factors and Lifestyle

A risk factor makes a disease more likely. It does not mean the disease is certain.

  • Risk factor Something linked to an increased rate of a disease.
  • Lifestyle The way a person lives, including diet, exercise, smoking and alcohol use.
  • Obesity Having so much body fat that health is at risk.
A diagram linking risk factors such as smoking, poor diet, obesity, alcohol and ionising radiation to the diseases they make more likely.
Many diseases are caused by an interaction of a number of factors, not just one.

Cancer

Cancer is uncontrolled cell division. A tumour is dangerous when it is malignant, because it spreads.

  • Cancer A disease caused by changes in cells that lead to uncontrolled growth and division.
  • Tumour A lump of abnormal cells.
  • Benign tumour A tumour that stays in one area and does not invade other parts of the body.
A benign tumour contained in a membrane, and a malignant tumour that invades the tissue around it, sends cells in the blood and forms a secondary tumour.
A benign tumour stays where it started. A malignant tumour spreads.

Benign and malignant tumours compared

  • Benign tumour A growth of abnormal cells; Contained in one area, usually inside a membrane; Does not invade other tissues
  • Malignant tumour A growth of abnormal cells; Invades neighbouring tissues; Cells spread in the blood to other parts of the body

How a cancer spreads

  • Cells change A change in a cell makes it divide in an uncontrolled way.
  • A tumour forms The cells build up into a lump, which keeps growing.
  • Invasion The cells of a malignant tumour invade the tissues around it.
  • Spreading in the blood Cells break off and travel round the body in the blood.