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Ch39: Effect of Disease Higher Human Biology

Ch39: Effect of Disease Higher Human Biology. Disease. Disease = an impairment of the normal functioning of part (or all) of the body. Caused by: Pathogenic (disease-causing) micro-organisms Deficient diet Stress. Regulatory Effect on a Population.

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Ch39: Effect of Disease Higher Human Biology

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  1. Ch39: Effect of Disease Higher Human Biology

  2. Disease Disease = an impairment of the normal functioning of part (or all) of the body. • Caused by: • Pathogenic (disease-causing) micro-organisms • Deficient diet • Stress

  3. Regulatory Effect on a Population The growth rate of a population is regulated by disease. If the population density gets to high, disease acts as a limiting factor causing the population to decrease – thus keeping the population in check (at its capacity). Dense populations are more likely to be attacked by disease-causing organisms, if it is fatal this will cause a high death rate.

  4. Disease & Human Population Examples of diseases that have had (or could have) a regulatory effect: • Bubonic plague (Black Death) • 13th –19th Century Europe • caused by a pathogenic bacterium • One epidemic in 14th century killed 25% View the Scholar animation: http://courses.scholar.hw.ac.uk/vle/scholar/session.controller?action=viewContent&contentGUID=1a112130-bbaa-de2c-a567-99d7ce1d69d4 • HIV (and AIDs)

  5. What is the difference between immunisation & vaccination? Immunisation = the process that increases people’s ability to resist a disease-causing organism. Vaccination = a method of immunisation that deliberately introduces a weakened or altered form of the pathogen (or virus) into the body so that the body can make antibodies against the antigen thus allowing the body to develop immunity to it.

  6. Smallpox In 1976, Edward Jenner immunised a boy against smallpox using cowpox virus as a vaccine. Many years later scientists have discovered how to produce vaccines for specific diseases 1840s Britain – free vaccination against Smallpox 1850s Britain – all babies vaccinated 1967 – World Health Organisation (WHO) introduced programme to eradicate Smallpox – completed in 1977

  7. Smallpox Eradication Worked because: • Able to vaccinate babies just after birth • Homed in on fresh out-breaks vaccinating all suspected contacts • Passes from human to human – NO animals can carry the disease • Immunity from vaccination lasts for long time • Single antigen involved so easier to produce a vaccine

  8. Malaria difficult to eradicate ….because: • Is carried by mosquitoes – has 2 hosts • Changes from one form to another – 3 phases • Vaccines only effective against one form of the pathogen • Many strains with different composition of antigenic proteins on their surfaces …. So it resists eradication & exerts a regulatory effect on the human population.

  9. Control of childhood diseases Developed Countries • Caused death 150 years ago: • measles • whooping cough • diphtheria • tetanus • polio • tuberculosis Vaccinations & higher standard of living have brought them under control. Vaccination targets of at least 95% are needed to provide protection for the population as a whole.

  10. Parents don’t bring children to be immunised or only get 1st dose Children remain susceptible & die Control of childhood diseases Developing Countries Child mortality from vaccine-preventable diseases is still very high. In 1974 – WHO launched their Expanded Program of Immunisation (EPI) to increase the vaccination of children against the 6 main common childhood diseases. • Lack of… • understanding • information • money

  11. Improved living conditions Vaccination & health care Improved Hygiene, Sanitation & Living conditions:Developed Countries Changing social & economic factors Increased resistance to disease • hygiene • waste disposal • nutrition • Modern epidemics (e.g. flu) are on a small-scale due to… • advanced warnings • vaccination for vulnerable • healthier population Minor outbreaks (e.g. cholera) are quickly contained

  12. No clean water No sewage disposal Improved Hygiene, Sanitation & Living conditions:Developing Countries In more than 50% of developing countries the majority of the population:

  13. Clean drinking water Mains sanitation Adequate diet Vaccination Improved Hygiene, Sanitation & Living conditions:Developing Countries Water contaminated by sewage contains pathogens that cause diseases (e.g. cholera & dysentery) 80% diseases in poor countries = water-related Diarrhoea most serious 50% deaths in children under 5 = Need….

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