Heath_ Disease

• Health


  A person's physical, mental and social condition
• Good health


  • More than being free from disease; it is having a positive outlook on life and feeling good physically
  • Requires proper shelter, nutrition, exercise, sleep and rest
  • Good hygiene and access to medical and social care are also important
• Disease


  A disorder or malfunction of the mind or body, which destroys good health
• Diseases


  • May have a single cause or be multifactorial
  • Have characteristic symptoms, which may be physical, mental or both
  • Acute diseases have a sudden onset with rapid changes, but only last for a short time
  • Chronic diseases have effects that may continue for months or years
• Categories of disease


  • Physical disease
  • Infectious disease
  • Non-infectious disease
  • Deficiency disease
  • Inherited disease
  • Degenerative disease
  • Mental disorder
  • Social disease
  • Self-inflicted disease
• Physical disease


  Involve temporary or permanent damage to the body
• Infectious disease


  Caused by pathogens such as viruses, bacteria, fungi, protoctists, worms and insects, which can be transmitted from person to person
• Carriers


  People who can transmit the pathogen but do not have the disease symptoms
• Non-infectious disease


  Not caused by pathogens and cannot be passed on by physical contact
• Deficiency disease


  Nutritional diseases caused by an inadequate or unbalanced diet
• Inherited disease


  Caused by genes and can therefore be passed from parent to child
• The most common inherited disease in Britain is cystic fibrosis, which is characterised by a build-up of sticky mucus
• Cystic fibrosis


  Caused by a recessive faulty allele, so parents may be carriers without having any symptoms
• Genetic diseases may be treated but not cured because we cannot replace the faulty gene
• In the future, drugs that act against the faulty gene causing a disease may be developed, which will have fewer side effects and be more effective
• The replacement of faulty genes or gene therapy may become commonplace
• Degenerative disease


  Characterised by a gradual loss of function, in one or several organs or tissues
• Main categories of degenerative diseases


  • Diseases of skeletal, muscular and nervous tissues
  • Cardiovascular diseases of the circulatory system
  • Cancers
• Mental disorder


  Affects a person's mind, but may be accompanied by physical symptoms
• Some mental diseases are caused by degeneration of brain tissue, while others seem to be accompanied by changes in the blood flow to the brain
• Social disease


  A very wide category that can include almost all infectious diseases and multifactorial diseases, which are influenced by people's living conditions and their personal behaviour
• Self-inflicted disease


  Caused by damage to a person's health by their own decisions and behaviour
• Endemic disease


  An infectious disease that is always present in a population
• Epidemic


  When a disease suddenly spreads rapidly and affects many people
• Pandemic


  When a disease spreads over a continent or even the world
• Epidemiology


  The study of patterns of diseases and the factors affecting its spread
• Collecting information on the distribution of disease helps to identify the underlying causes and if it turns out to be infectious, may point to how it is transmitted
• Data on morbidity (numbers ill) and mortality (numbers who have died) for a disease when expressed in certain ways enables comparisons across cities or countries to be made
• In developing countries, the main cause of death is infectious diseases, while in developed countries, very few deaths are caused by pathogens
• The incidence of infectious disease is low in developed countries due to vaccination, good standards of hygiene and nutrition, and the availability of antibiotics
• In the richer countries, degenerative diseases are the biggest killers, mainly due to lifestyles that put people at risk of heart disease and cancers
• Tobacco companies do not declare the ingredients in cigarettes, but upon analysis, they contain over 4000 different chemicals, many of which are toxic
• Main ingredients in cigarettes that damage health

  • Tar
  • Carbon monoxide
  • Nicotine
• Tar


  A mixture of aromatic substances, which settles on the airway linings and stimulates changes that may lead to obstructive lung disease and lung cancer
• Carbon monoxide


  This gas diffuses across the alveoli into the blood and onto the red blood cells, combining with haemoglobin to form carboxyhaemoglobin, which stops the haemoglobin from becoming fully saturated and so it carries 5-10% less oxygen
• Nicotine


  This drug is absorbed readily into the blood and stimulates the nervous system to reduce the diameter of arterioles and the adrenal glands to release adrenaline, which increases heart rate and blood pressure and decreases the blood supply to the extremities
• Nicotine also causes platelets to become stickier, which can lead to an increased risk of blood clots forming
• Diseases caused by smoking

  • Chronic bronchitis
  • Emphysema
  • Chronic obstructive pulmonary disease
  • Lung cancer
• Chronic bronchitis


  Tar stimulates goblet cells and mucus glands to enlarge, producing more mucus, which builds up and blocks the smallest bronchioles
• Emphysema


  Due to constant infection, phagocytes release elastase which breaks down the elastin in the alveoli walls, causing them to recoil and many to burst, reducing the surface area for gas exchange