Infection & Response

• Communicable diseases 


  Can be spread from person to person

  Spread by pathogens (bacteria, viruses)
• Non communicable diseases 


  Cannot be passed from person to person
• Bacteria


  once inside the human body, bacteria reproduce rapidly

  and release toxins

  make us feel ill, damage tissues, can be killed by antibiotics
• Virus


  Cannot reproduce themselves, can only reproduce inside a host cell by invading it

  can cause host cell to burst open and die, can’t be killed by antibiotics
• Pathogens spread


  Spread in the air (sneezing, coughing)

  Spread by dirty water (cholera)

  Direct contact between people
• Reduce pathogen spread 


  Wash hands before eating

  Drink clean water

  Use condoms during sex

  Isolation

  Vaccinations
• Measles


  SYMPTOMS- fever, red rash,

  SPREAD- water droplets (coughing, sneezing)

  FUTURE- can cause breathing problems, brain damage

  PREVENT- vaccination
• HIV


  SYMPTOM- flue, damaged immune system, AIDS

  TREATMENT- antiretroviral drugs (take for lifetime)

  SPREAD- exchange of fluids between humans
• Salmonella


  Spread by food prepped in unhygienic conditions

  SYMPTOMS- fever, cramps, vomiting, diarrhoea
• Gonorrhoea


  Sexually transmitted disease STD

  SYMPTOMS- thick yellow discharge from sexual organ, pain when urinating

  TREATMENTS- penicillin

  PREVENT- condoms
• Malaria


  Communicable disease, passed around by mosquitoes

  Causes high rates of fever, can be fatal

  Preventions- mosquito nets, fly spray, insecticide
• Non specific defence system

  • Prevent pathogens entering the body
  • Skin (protective layer)
  • Nose contains hair and mucus (trap pathogens)
  • Trachea & bronchi have tiny hairs down them
  • Stomach contains hydrochloric acid
• The immune system


  Destroys pathogens & toxins they produce

  Protects us invade the same pathogen invades again
• White blood cells


  Ingests and destroy pathogens

  Uses enzymes to destroy it

  Makes antibodies
• Antibodies 


  Protein molecule produced by white blood cells

  Antibodies stick to pathogens, causing them to be destroyed

  Remain in the blood for a long time
• Antitoxins


  Produced by white blood cells

  Stick to toxins to prevent them damaging anymore cells
• Tobacco mosaic virus TMV

  Causes leaves to discolour in a mosaic pattern

  Causes rate of photosynthesis to lower

  Causes stunted growth
• Rose black spot 


  Caused by fungus

  Leaves develop purple or black spots

  Photosynthesis falls, stunted growth

  Spread by wind and water

  Spray with chemicals or destroy infected leaves
• Vaccines and how they work 


  Introduce small amounts of dead or inactive pathogens

  White blood cells bow work to produce antibodies by using mitosis to divide itself
• Herd immunity


  When a large number of people are vaccinated against the same pathogen
• Antibiotics


  Kill invasive harmful bacteria while leaving good body cells alone
• Antibiotics resistance 


  Certain antibiotics are no longer effective against certain bacteria, due to over usage and the bacteria developed
• Medicine origin


  Foxgloves used to extract digitalis

  Aspirin extracted from willow trees

  Fleming discovered penicillin
• Medicine testing 


  Test the drugs toxicity to see if it’s safe to take

  Check if drugs effective for treatment required

  TESTED ON- Cells, tissues, animals

  Then low doses are given to healthy volunteers
• Placebo 


  Medication with no active drug in it

  Some patients will get better if they believe they are taking a drug making them better

  Doctors and patients don’t know who have the placebo