topic b3- infection and response

• communicable diseases

  • rose black spot
  • malaria
  • salmonella
  • gonorrhoea
  • measles
  • HIV
  • tobacco mosaic
• rose black spot

  • pathogen- fungus
  • spread- water and wind
  • symptoms:
  • purple/ black spots on leaves, can turn yellow and drop off
  • reduced growth
  • treatment:
  • removing/ destroying infected leaves
  • fungicides
• malaria

  • pathogen- protist
  • spread- mosquito vectors
  • symptoms:
  • fever
  • can be fatal
  • treatment:
  • mosquito nets
  • stop mosquitos from breedings
• salmonella

  • pathogen- bacterium
  • spread- eating contaminated food
  • symptoms:
  • fever
  • stomach cramp
  • vomiting
  • treatment:
  • vaccination of poultry
• gonorrhoea

  • pathogen- bacterium
  • spread- sexual contact
  • symptoms:
  • pain when urinating
  • discharge
  • treatment:
  • condoms
  • antibiotics
• measles

  • pathogen- virus
  • spread- airborne droplets
  • symptoms:
  • fever
  • red skin rash
  • treatment:
  • vaccination of children
• HIV

  • pathogen- virus
  • spread- sexual contact, exchanging bodily fluids
  • symptoms:
  • flu-like (initially)
  • damaged immune system (late-stage)
  • treatment:
  • condoms
  • avoid sharing needles
  • antiretrovirals
• tobacco mosaic

  • pathogen- virus
  • spread- by direct contact between plants
  • symptoms:
  • mosaic pattern on leaves
  • which reduces photosynthesis and growth
  • treament:
  • don't need to know
• non-communicable diseases

  • not passed from one organism to another
  • they can be inherited- some people carry a gene that predisposes them to some conditions (e.g. cancer)
  • other causes:
  • poor diet
  • lack of exercise
  • overexposure to the sun
  • misuse of drugs
• non-specific defence systems against pathogens

  1. skin= acts as a barrier and secretes antimicrobial substances to kill pathogens
  2. nose= hairs and mucus trap particles containing pathogens
  3. trachea/ bronchi= mucus traps pathogens, and cilia waft mucus up to the throat so that it can be swallowed
  4. stomach= hydrochloric acid kills pathogens
• vaccination

  vaccinating a large proportion of the population reduces the spread of pathogens, so that even people who are vaccinated are unlikely to catch the disease
• 3 ways which white blood cells attack pathogens

  1. phagocytosis:

  • white blood cell- pathogen engulfed and digested

  1. producing antibodies:

  • white blood cell- pathogen with antigens- antibodies specific to pathogen produced- antibodies attack all copies of the pathogen in the body

  1. producing antitoxins:

  • these counteract toxins produced by invading bacteria
• types of drugs

  • antibiotics kill bacteria
  • specific antibiotics kill specific types of bacteria
  • viruses live and reproduce inside cells
  • painkillers treat the symptoms of disease but don't kill pathogens
  • bacteria can become resistant to antibiotics
• where drugs come from

  • drug-type-source:
  • digitalis-heart drug-foxgloves
  • asparin-painkiller-willow
  • penicillin-antibiotic-penicillium mould
  • penicillin was discovered by alexander fleming
• drugs tested for

  • toxicity- how harmful the drug is
  • efficacy- whether it works and produces the effect you're looking for
  • dosage- how much should be given
• preclinical testing

  • tests on human cells and tissues
  • tests on live animals
• clinical trials

  • tests on healthy volunteers
  • dosage is increased
  • tested on ill patients to find optimum dose
• double blind trial

  • where the patient is either given the drug or a placebo, however they don't know which one they were given, neither does the doctor
  • this is to make the trial fair
• placebo- fake drug

  • a substance that looks like a drug, but isn't
  • doesn't contain active drug