infection and response

• communicable diseases

  • pathogens are microorganisms that enter body and cause disease
  • communicable = easily spread
  • plants and animals can be infected
• bacteria

  • very small living cells
  • reproduce rapidly in your body
  • make you feel ill by producing toxins , that damage your cells
• viruses

  • not cells - much smaller
  • reproduce rapidly in your body
  • live inside your cells and replicate themselves , cell will usually burst - releasing viruses - cell damage make you feel ill
• protists

  • sing - celled eukaryotes
  • some are parasites , transferred by vectors
• fungi

  • sing-celled and multicellular
  • have a boy which is made up of hyphae
  • can grow and penetrate human skin
  • produce spores
• how its spread

  • water - drinking , bathing in dirt water e.g. cholera
  • air - breathed in , droplets produced by coughs or sneeze
  • direct contact - touching contaminated things e.g. athletes foot
• measles

  • viral disease spread by droplets
  • develop red skin and rash and show signs of fever
  • fatal if complications = pneumonia or inflammation of the brain
  • most are vaccinated
• hiv

  • virus spread by sexual contact and exchanging bodily fluids
  • flu-like symptoms , controlled with anti-retroviral drugs
  • attacks immune cells
  • cant cope with other infections
• tobacco mosaic virus (TMV)

  • affects plants
  • causes mosaic pattern on leaves - become discoloured
  • cant carry out photosynthesis - affect growth
• rose black spots

  • fungus causing purple / black spots
  • less photosynthesis occurs = less growth
  • spreads through environments in water or wind
  • treat disease using fungicides or destroying affected plants
• malaria

  • caused by a protists
  • life cycle takes place inside a mosquito - they are vectors - pick up malaria when they feed on infected animals
  • causes repeating episode of fever -m can be fatal
  • reduced by stopping mosquitoes from breeding
  • protected using insecticides and mosquito nets
• salmonella

  • type of bacteria causes food poisoning
  • suffer from fever , stomach cramps , vomiting , diarrhoea
  • caused by toxins that bacteria can produce - eating food that has been contaminated
  • uk poultry is vaccinated
• gonorrhoea

  • sexually transmitted disease (STD)
  • passed by sexual contact - caused by bacteria
  • symptoms = pains while urinating , yellow green discharge
  • resistant to penicillin - treated with antibiotics
  • use barrier methods
  • being hygienic , destroying vectors , isolating infected individuals and vaccination
• 1st level of fighting disease

  • skin acts as a barrier - secretes antimicrobial pathogens
  • hairs and mucus trap particles - containing pathogens
  • trachea and bronchi secrete mucus - lined with cilia = waft mucus up throat
• 2nd line of defence

  • wbc can engulf foreign cells and digest them - phagocytosis
  • produce antibodies specific to antigens - be found and destroyed
  • they are produced rapidly and if infected again will rapidly reproduce
  • producing antitoxins = counteract toxins produced by invading bacteria
• vaccination

  • injecting small amounts of dead / inactive pathogens , make your body produce antibodies so if the same pathogens enter your body can rapidly fight them
  • pros = control communicable disease
  • cons = bad reaction , dont always work
• drugs

  • painkillers = relieve pain dont tackle cause
  • antibiotics = kill bacteria specific to bacteria
  • antibiotics dont destroy viruses as they reproduce inside your cells - difficult to develop drug that wont damage your cells
  • bacteria can mutate - become resistant
  • aspirin - found in willow
  • digitalis - found in foxgloves
  • alexander flemming discovered penecillin - from mould
• developing drugs

  • preclinical testing = human cells / tissues
  • cant test the affect on whole / multiple body systems
  • preclinical testing = live animals - test efficacy , toxicity
  • clinical trials = healthy human volunteer = test toxicity
  • clinical trials = ill volunteers = test toxicity
  • suggested double blind trial
• monoclonal antibodies

  • mouse injected with chosen antigen
  • b-lymphocytes taken from mouse
  • fast - diving tumour from lab
  • fused together
  • makes hybridoma
  • divides quickly to produce a lot of clones
• pregnancy tests

  • hcg found in urine when pregnant
  • stick has antibodies to hormone with dye attached
  • test strip has antibodies to the hormone on it
  • if pregnant = hormone binds to antibodies on blue heads , urine moves up stick carrying hormone . the beads and hormone bind to antibodies on strip - blue beads get stuck on strip turning it blue
• anticancer drugs

  • can be attached to monoclonal antibodies
  • radioactive substance , a toxic drug
  • antibodies given to patient through a drip
  • antibodies target specific cells because they only bind to those
  • drug kills cancer cells but not any others
  • bind to hormones and other chemicals in blood to measure levels
  • test blood samples in laboratories for certain pathogens
  • locate specific molecules on cell or tissue
  • advantages = cancer treatment , less side effects than chemo
  • disadvantages = not widely used
• mineral ion deficiency

  • nitrates = needed for proteins/growth if lacking stunted growth
  • magnesium = needed for chlorophyl / photosyntheses if lacking chlorosis and yellow leaves
• plant disease

  • symptoms = stunted growth , abnormal growths , spots on leaves , malformed stems or leaves , patches of decay , discolouration
  • identified = gardening manual , website , laboratory , testing kits
  • physical defences = waxy cuticle , cell walls / cellulose , bark
  • chemical defences = antibacterial chemicals , produce poisons
  • mechanical defences = thorns and hairs , leaves droop or curl , mimicry