Infection and responses

• Name four types of pathogens

  viruses, bacteria, protists, fungi
• What is. Pathogen


  A microorganism that causes disease
• 7 ways terms are transmitted

  Droplets , airborne , direct contact , indirect contact , water borne , food borne , vector borne
• What does bacteria do?

  Produces toxins which damages our tissue
• What do viruses do?

  Live in our cells and replicate causing damage to them
• Name 3 viral diseases

  measles, HIV, tobacco mosaic virus
• Name 2 bacterial diseases

  Salmonella and gonorrhoea
• Name a protist disease and explain it

  Malaria. Mosquitoes are vectors as they pick up the protist when they feed on an infected animal. Every time the mosquito feeds on another animal, it infects it by inserting the protist into the animal's blood vessels. It causes repeating episodes of fever.It can be reduced by stopping mosquitoes from breeding and by protecting people by using insecticides and mosquito nets.
• Name a fungal disease and explain it

  Rose black spot is a fungus that causes purple or black spots to develop on the leaves of rose plants. The leaves then turn yellow and fall off. This means less photosynthesis happens so the plant doesn't grow properly. It spreads through the environment in water or by the wind. Gardeners treat the disease using fungicides and by stripping the plant of its affected leaves. Those leaves are then destroyed so that the fungus can't spread to other rose plants.
• Name 2 bacterial diseases and explain them :

  Salmonella - is a food poisoning spread by bacteria's ingested in food or in food prepared in unhygienic conditions. Bacteria can be found in raw meat, eggs etc. will often get cramps, vomiting and diarrhoea. To prevent wash hands and surfaces throughly and keep raw meat away from cooked food and finally cook food throughly.

  
  

  Gonorrhoea - is a sexually transmitted disease with symptoms of thick green or yellow discharges from the vagina or penis and pain when urinating. Is caused by a bacterium. Can be controlled with antibiotics or the use of barrier method like condoms.
• Name 3 viral diseases and explain them :

  Measles - symptoms of fever and red skin rash. Can be fatal if complications arise. Most young children are vaccinated. Spread by inhalation of droplets from sneezes and coughs.

  
  

  HIV - flu like symptoms attacks the immune system and can lead to AIDS. Is spread by exchange of bodily fluids by sexual contacts or bodily fluids ,like blood when drugs users share needles. To prevent use barriers e.g. condom, do not share needles and use of antiretroviral drugs

  
  

  Tobacco mosaic virus (TMV) - discolouration of the leaves effected part of the leaf can't photosynthesise that leads to reduction of the yield. It's spread by contact between diseased and healthy plants, insects act as vectors. Prevention can be pest control and growing TMV resistant strains.
• How can we limit the spread of pathogens :

  . Hygiene- wash hands, using disinfectants, isolating raw meat and using tissues when sneezing

  . Reducing contact with infected individuals

  . Removing vectors - using pesticides or insecticides

  . Vaccination- by injecting it into a persons body they can become immune to it so it will not infect them. This means they cannot pass it on.
• First line of defence is .....

  Natural barriers to infection
• What is mucus's function ? ( first defence )

  Has lining that traps dirt and microbes
• What is saliva's function ? ( first defence )

  Has antibacterial enzymes
• What are the function of tears ? ( first defence )

  They have antibacterial enzymes
• What is the function of the skin ? ( first defence )

  Prevents entry of bacteria
• What is the function of stomach acid ? ( first defence )

  Has a low pH that kills harmful microbes
• second line of defense is .......

  Non specific ( innate immune system )
• Third line of defence is ......

  ( specific immune system )
• What are the 3 roles of white blood cells ?

  Producing antibodies and antitoxins and engulfing microorganisms
• What is phagocytosis?


  This destroys pathogens so they can no longer make you feel ill.
• What effect does producing antibodies have on pathogens ?

  Every pathogens has an antigen on its surface, which is a structure which a specific complementary antibody can bind to. Once antibodies begin to bind to the pathogen the pathogens start to clump together resulting in white blood cells being able to locate pathogens quicker and easier.

  
  

  If you are infected again with the same pathogen, the specific complementary antibodies will be produced ata a faster a rate. The individual will no feel symptoms of illness as they are then immune.
• What is a vaccine?

  Is a small quantity of dead , in active , live attenuated or a genetically modified version of a pathogen
• What happens when you get a vaccine ?

  When you have a secondary infection the antibodies produce much quicker so the pathogen can be destroyed. Vaccinations replicate the first infection so when the person is exposed to the real disease they don't feel symptoms. This stimulates the white blood cells to produce antibodies complementary to the antigens on the pathogen.
• What are the advantages and disadvantages of vaccines ?

  Advantages :

  - they have eradicated many disease so far e.g. smallpox and reduced the occurrence of many e.g. rubella

  - epidemics (lots of cases in an area) can be prevented through herd immunity.

  
  

  Disadvantages :

  - they are not always effective in providing immunity

  - bad reactions for example fevers can occurs in response to vaccines but it's very rare
• Antibiotics


  Treat a specific disease, there are medicines like penicillin that help cure bacterial disease by killing infective bacteria inside the body
• Painkillers do what


  Treat symptoms and they don't kill pathogens
• What are the 3 stages of drug development

  1) Computer modelling - software is used to theoretically examine of test 2) Testing in the lab on cells or animals 3) Clinical trials on humans
• What 3 things do we test for during clinical trials ?

  1) toxicity 2) efficacy 3) dose (TED)
• What is a placebo ?

  A "fake" drug, often a sugar pill to see if improvements are psychological rather than physical
• What is a double blind trial ?

  A trial where neither the patients nor the doctor know which group is given the real drug and which is given the placebo
• Digitalis


  Is a drug for the heart and is found in foxglove
• Aspirin


  Is a anti inflammatory and comes from the bark of willow tree
• Penicillin


  It is a antibiotic and is found in penicillium mould
• What is antigen?


  a protein on the surface of a pathogen that stimulates an immune response
• What is a monoclonal antibody?

  an antibody produced by a single clone of cells
• The process of monoclonal antibodies

  First The mouse is INJECTED then , they DETACH the antibodies (which have been stimulated in order to produce a specific antibody) from the mouse in operation . Tumour cells are called MYELOMA cells they multiply quickly.The antibodies and myeloma cells form as HYBRIDOMA cell They are then Grown in the lab and when grown they produce antibodies. Single hybridoma cells are cloned to produce many identical cells that all produce the same antibody. The antibodies are SEPARATED and then the ANTIBODIES are collected and purified.
• What are 4 uses of monoclonal antibodies ?

  1. Pregnancy tests

  2. In labs to measure and monitor

  3. In research o find or identify certain molecules on a cell or tissue

  4. In the treatment of disease e.g. cancer
• What effect does a toxins have on pathogens ?

  They neutralise the toxins released by the pathogen by binding to them