Infection and Response

    Cards (55)

    • pathogens are microorganisms that enter the body and cause disease

      they cause communicable diseases that can easily spread
      both plants and animals can be infected by pathogens
      pathogens can be BACTERIA, VIRUSES, PROTISTS, or FUNGI
    • Bacteria are very small cells which can reproduce rapidly inside your body

      they can make you feel ill by producing TOXINS that damage your cells and tissues
    • Viruses are not cells- they are smaller

      they can reproduce rapidly inside your body
      they live inside your cells and replicate themselves using the cell' machinery to produce many copies of themselves
      the cell will then burst, releasing the new viruses
      the cell damage makes you feel ill
    • protists are single-celled eukaryotes

      some protists are parasites- parasites live on or inside other organisms and can cause them damage. they are often transferred to the organism by a vector, which doesn't get the disease itself
    • fungi come in different shapes
      some are single celled
      others have a body which is made up of HYPHAE- thread like structures
      these hyphae can grow and penetrate human skin and the surface of plants causing disease
      the hyphae can produce spores, which can be spread to other plants and animals
    • pathogens can be spread in different ways

      water
      air
      direct contact
    • pathogens can be spread through water
      some pathogens can be picked up by drinking or bathing in dirty water
      cholera is a bacterial infection that's spread by drinking water contaminated with the diarrhoea of other sufferes
    • pathogens can be spread through air
      pathogens can be carried in the air and can then be breathed in
      some airborne pathogen are carried in the air in droplets produced when you cough or sneeze- the influenza virus is spread this way
    • pathogens can be spread through direct contact
      some pathogens can be picked up by touching contaminated surfaces including the skin
      athletes foot is a fungus which makes skin itch and flake off, it is commonly spread by touching the same things as an infected person
    • Measles is a VIRUS
      measles is spread by droplets from a contaminated sneeze/cough
      people with measles develop a red skin rash, and a fever
      measles can be serious or even fatal if there are complications (pneumonia)
      most people are vaccinated when they are young
    • HIV is a VIRUS
      HIV is a virus spread by sexual contact, or exchanging bodily fluids such as blood from shared needles
      initially causes flu-like symptoms, usually the person doesn't experience symptoms for a few years, HIV can be controlled using antiretroviral drugs which stop the virus replicating
      the virus attacks the immune cells meaning it can't cope with other infections or cancer- late stage HIV or AIDS
    • Tobacco Mosaic Virus (TMV)

      TMV is a virus that affects many species of plants
      it cause a mosaic pattern on the leaves of plants, causing them to become discoloured
      the discolouration means photosynthesis can't be carried out well, so the plant growth is stunted
    • Rose Black Spot is a FUNGAL disease

      rose black spot is a fungal disease that cause purple/black spots on the leaves of rose plants- can turn yellow and drop off
      photosynthesis happens less- plant doesn't grow well
      spreads through the environment- water/wind
      gardeners treat the disease using fungicides and by stripping the plant of affected leaves- the leaves need to be destroyed so they cannot spread
    • malaria is caused by a PROTIST

      part of the malaria's life cycle takes place inside a mosquito
      the mosquitoes are vectors that pick up the malaria protist when feeding on the infected animal
      every time the mosquito feeds on another animal, it infects it by invading the protist into the blood vessels
      malaria cause repeating episodes of fever- can be fatal
      people can be protected using mosquito nets or insecticides
    • salmonella is a BACTERIAL disease

      salmonella is a bacteria that causes food poisoning
      infected people can suffer fever, stomach cramps, vomiting, diarrhoea
      these symptoms are cause by the toxins that bacteria produces
      salmonella is passed through food that has been contaminated
    • gonorrhoea is a BACTERIAL disease
      gonorrhoea is a sexually transmitted disease (STD)
      STD's are passes through sexual contact
      a person with gonorrhoea will get pain when they urinate, thick yellow green discharge from the vagina or penis
      originally treated with penicillin, but strains have become resistant
      people can be treated with antibiotics and should have barrier methods of contraception
    • The spread of disease can be reduced or prevented
      being hygienic
      destroying vectors
      isolating infected individuals
      vaccination
    • being hygienic can reduce the spread of disease

      using simple hygiene measures can prevent the spread of disease
      washing hands etc
    • destroying vectors can prevent the spread of disease
      by getting rid of organisms that spread disease, you can prevent the disease from being passed on
      vectors that are insects can be killed using insecticides or by destroying their habitat so they can no longer breed
      the spread of malaria can be prevented by stopping mosquitoes breeding
    • isolating individuals can reduce the spread of disease
      if you isolate someone who has a communicable disease, it prevents them from passing it on to somebody else
    • vaccination can prevent the spread of disease
      vaccinating people and animals against communicable diseases means that they can't develop the infection and then pass it on to someone else
      most poultry in the united kingdom is vaccinated against salmonella
    • the human body has features to prevent the entry of pathogens

      the skin acts as a barrier and secretes antimicrobial substances which kill pathogens
      hairs and mucus in the nose trap particles that may contain pathogens
      the trachea + bronchi secrete mucus to trap pathogens, they are lined with cilia which waft the mucus to the back of the throat
      the stomach produces hydrochloric acid to kill pathogens
    • the immune system can attack pathogens

      white blood cells are in charge of destroying invading pathogens
      -consuming them
      -producing antibodies
      -producing antitoxins
    • phagocytosis
      white blood cells can engulf foreign cells and digest them
    • white blood cells can produce antibodies

      every invading pathogen has an antigen on their surface
      when some types of white blood cell come across a foreign antigen they produce proteins called antibodies to lock onto the invading cells so they can be found and destroyed by other white blood cells
      antibodies are produced rapidly and carried round the body to find all similar bacteria or viruses
    • white blood cells can become memory cells

      if the person is infected with the same pathogen again the white blood cells will rapidly produce the antibodies to kill it, the person is naturally immune to that pathogen and won't get ill
    • white blood cells can produce antitoxins
      these toxins counteract toxins produced by the invading bacteria
    • vaccinations can prevent future infections

      vaccination involves injecting a dead or weakened version of a pathogen into the body. these carry antigens which cause your body to produce antibodies to attack them
      if the body is infected with that pathogen again, the white blood cells rapidly mass-produce antibodies to kill the pathogen
    • pros of vaccination

      vaccines help control a lot of communicable diseases
      big outbreaks can be prevented if the majority of the population is vaccinated (herd immunity)
    • cons of vaccination

      sometimes the vaccine doesn't work
      the vaccine can cause side effects and bad reactions can occur
    • some drugs just relieve symptoms
      painkillers are drugs that relieve pain-they reduce the symptoms
      antibiotics kill the bacteria causing the problem without killing your body cells different antibiotics kill different bacteria so it is important to use the correct one- strains have become resistant
      antibiotics don't destroy viruses- viruses reproduce using the body cells which makes it difficult to produce a drug that kills just the virus
    • bacteria can become resistant to antibiotics

      bacteria can mutate- the mutations can cause them to be resistant
      when the infection is treated, the non-resistant bacteria will be killed
      the individual resistant bacteria will survive and reproduce, meaning the population of the resistant strain will increase
      the resistant strain can cause a serious infection that cannot be treated
      to slow down the rate of resistant bacteria, doctors should avoid over prescribing antibiotics people must finish the course of antibiotics
    • many drugs originate from plants
      plants produce a variety of chemicals to defend themselves against pests and pathogens
      some of theses chemicals can be used to treat human diseases or relieve symptoms
      a lot of current medication were discovered by studying plants used in traditional cures
    • some drugs were extracted from microorganisms
      Alexander Fleming cleared out some Petri dishes containing bacteria- some had mould on it and the area around the mould was free of bacteria
      he discovered the mould was a substance that killed the bacteria
    • today, drugs are made on a large scale in the pharmaceutical industry

      they are synthesised by chemists in labs
    • There are three main stages in drug testing

      preclinical testing
      -human cells
      -live animal cells
      clinical trial
    • preclinical testing

      tested on human cells and tissues, but cannot see how they affect whole systems
      live animals to test efficacy(whether the drug works) and to find out its toxicity(how harmful it is) and to find the best dosage(the concentration and how often)
    • clinical trial

      first tested on healthy volunteers to make sure it doesn't have any harmful side effects- at the start a very low dose is given, which is gradually increased
      if the results are good, the drug can be tested on people suffering from the illness
      the optimum dosage is found, the most effective with the least side effects
    • drugs are tested on people suffering with the disease

      they are split into two groups
      some are given placebos(a substance that is like the drug being tested but has no effect) while others are given the new drug
    • Monoclonal Antibodies are identical antibodies

      antibodies are produced by b-lymphocytes (A type of white blood cell)
      monoclonal antibodies are produced from lots of clones of a single white blood cell
      this means all the antibodies are identical and will target one specific antigen