B1.1 Keeping Healthy Key Points

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B1 1.1 Diet and exercise

  • Most people eat a varied diet, which includes everything needed to keep the body healthy.
  • Different people need different amounts of energy.
  • The metabolic rate varies from person to person.
  • The more exercise you take, the more food you neeed.
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B1 1.2 Weight problems

  • If you take in more energy than you use, you will store the excess as fat.
  • Obese people have more health problems than others.
  • People who do not have enough to eat can develop serious health problems.
  • Exercise helps reduce weight and maintain health.
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B1 1.3 Inheritance, exercise and health

  • Inherited factors affect our health. These include our metabolic tare and cholesterol level.
  • People who exercise regularly are usually healthier than people who take little exercise.
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B1 1.4 Pathogens and disease

  • Infectious diseases are caused by microorganisms called pathogens, such as bacteria and viruses.
  • Bacteria and viruses reproduce rapidly inside your body. Bacteria can produce toxins which make you feel ill.
  • Viruses damage your cells as they reproduce. This can also make you feel ill.
  • Semmelweis recognised the importance of hand-washing in preventing the spread of infectious diseases in hospital.
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B1 1.5 Defence mechanisms

  • Your body has several methods of defending itself against the entry of pathogens using the skin, the mucus of the breathing system and the clotting of the blood.
  • Your white blood cells help to defend you against pathogens by ingesting them, making antibodies and making antitoxins.
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B1 1.6 Using drugs to treat disease

  • Some medicines relieve the symptoms of disease but do not kill the pathogens which cause it.
  • Antibiotics do not destroy viruses because viruses reproduce inside the cells. It is difficult to develop drugs that can destroy viruses without damaging your body cells.
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B1 1.7 Growing and investigating bacteria

  • An uncontaminated culture of microorganisms can be grown using sterilised Petri dishes and agar. You sterilise the inoculating loop before use and seal the lid of the Petri dish to prevent unwanted microorganisms getting in. The culture is left at about 25*c for a few days.
  • Uncontaminated cultures are needed so we can investigate the effect of chemicals such as disinfectants and antibiotics on microorganisms.
  • Cultures should be incubated at a maximum temperature of 25*c in schools and colleges to reduce the likelihood of harmful pathogens growing.
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B1 1.8 Changing pathogens

  • Many types of bacterium have developed antibiotic resistance as a result of natural selection. To prevent the problem getting worse we muct not overuse antibiotics.
  • If bacteria or viruses mutate new strains of the pathogen can appear causing disease.
  • New strains of disease which spread rapidly can cause epidemics and pandemics. Antibiotics and vaccinations may not be effective against the new strain.
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B1 1.9 Immunity

  • Your white blood cells produce antibodies to destroy the pathogens. Then your body will respond rapidly to future infections by the same pathogen, by making the correct antibody. You become immune to the disease.
  • You can be immunised against a disease by introducing small amounts of dead or inactive pathogens into your body.
  • We can use vaccinations to protect against both bacterial and viral pathogens.
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B1 1.10 How do we deal with disease?

  • Vaccination protects individuals and society from the effects of a disease.
  • The treatment of disease has changed as our understanding of how antibiotics and immunity has increased.
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