13.1 - Health & Disease

Health and the factors that affect it

• Health is the state of physical and mental wellbeing - and, as the World Health Organisation puts it, of social wellbeing too, and not merely the absence of disease or infirmity.
• Being healthy is about more than just not being ill: someone who is physically fit can still be unhealthy if they have mental health problems or are socially isolated.
• A disease is a condition that impairs the normal functioning of an organism, and is one of the major causes of ill health.
• Both animals and plants can get diseases.

Causes of disease and ill health

• Infection by a pathogen - A pathogen invades the organism
• A mutation in an organism's genes
• Environmental conditions - E.g. a plant that doesn't get enough light won't grow properly
• Diet, lifestyle or life situation - A person's day-to-day circumstances

A disease shows itself through symptoms - changes in the organism that indicate disease is present - although these aren't always obvious, especially in the early stages.

Other factors that affect health

• Diet - A good, balanced diet gives the body what it needs, whereas a poor diet harms both physical and mental health
• Stress - Being under constant stress can cause health problems
• Life situation - This includes whether a person can get hold of medicines to treat illness and the things that help prevent it

Communicable and non-communicable disease

Diseases fall into two groups, depending on whether they can spread between organisms.

Communicable (infectious) diseases

• Can spread from one organism to another - between people, or between animals and people.
• Are caused by pathogens.
• Examples: measles and malaria.

Non-communicable diseases

• Cannot be passed between organisms.
• Tend to last a long time and get worse slowly.
• Examples: asthma, cancer, and coronary heart disease.

The cost of disease

• Both communicable and non-communicable diseases are costly to treat, and that cost falls on society as a whole.
• Preventing disease matters as well as treating it, because the overall cost to society is high.

Costs to the health service

• Many diseases need long-term treatment and long stays in hospital.
• Treatment can require expensive drugs and highly trained specialist staff.
• Together these place a heavy burden on the health service.

Costs to families and the economy

• People who care for someone who is ill may need time off work.
• People who are ill may be less productive or unable to work at all.
• As a result, widespread disease holds back a country's economy.