b2

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  • Created by: bwillows1
  • Created on: 11-05-14 13:24
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  • B2
    • microorganisms and disease
      • the effects an infection has on the body such as fever or rash are called symptoms
        • different microorganisms cause different symptoms but all damage body cells
          • some microorganisms damage body cells directly
            • e.g - malaria parasites invade red blood cells and multiply inside of them eventually making the cells burst open. malaria causes flu like symptoms
      • many infectious microorganisms produce poisons (toxins) that damage cells
        • some bacteria produce proteins that damage the material holding the cells together
          • this helps bacteria to invade the body deeper
            • staphylococcus bacteria is caused by food poisoning
        • other microorganisms produce toxins that poison cells causing fever or inflamation
          • some strains of Escherichia coli cause diarrhoea by secreting toxic substances
      • microorganisms produce quickly inside the human body
        • reproduce by making copies of themselves
          • to do this they need a source of nutrients for energy, they need warm moist conditions so that chemical reactions inside them can take place
            • in the body (especially intestines) we have all these conditions so bacteria can quickly multiply
      • viruses need other cells to reproduce
        • they use parts of other cells to make copies of themselves
          • certain viruses easily produce inside the human body as there are lots of the right kinds of cells for them to use.
    • the immune system
      • role of the immune system is to deal with any infectious microorganisms that enter the body
        • an immune response always involves white blood cells
          • anything that gets into the body should be picked up straight away by a certain type of  white blood cell
            • able to detect things that are 'foreign' to the body EG microorganisms
              • these white blood cells are non specific and attack anything that is nor meant to be there
            • there are different types
              • a different group of white blood cells attack specific microorganis
                • these white blood cells have receptors that recognize particular antigens
                  • antigens are substances that trigger immune responses
                    • they are usually protein molecules on the surface of a microorganism cell
                  • certain types of white blood cells produce antibodies
                    • antibodies are proteins specific to a particular antigen
                      • different microorganisms have different anitgens
                    • antibodies latch on to invading microoragnisms
                      • then they do one of 3 things...
                        • some can attach to bacteria and kill them directly
                        • mark the microorganism so another white blood cell can engulf and digest it
                        • bind to neutralise viruses or toxins
                      • once the right blood cell recognises the antigens on a microorganism it divides to make more identical cells which makes lots of the right antibody to fight the infection
                        • some white blood cells stay in blood = MEMORY CELLS
                          • memory cells can produce very quickly if the same antigen enters the body for a second time
                            • fight of infection before you become iill
                              • = IMMUNE
          • there are different types
            • a different group of white blood cells attack specific microorganis
              • these white blood cells have receptors that recognize particular antigens
                • antigens are substances that trigger immune responses
                  • they are usually protein molecules on the surface of a microorganism cell
                • certain types of white blood cells produce antibodies
                  • antibodies are proteins specific to a particular antigen
                    • different microorganisms have different anitgens
                  • antibodies latch on to invading microoragnisms
                    • then they do one of 3 things...
                      • some can attach to bacteria and kill them directly
                      • mark the microorganism so another white blood cell can engulf and digest it
                      • bind to neutralise viruses or toxins
                    • once the right blood cell recognises the antigens on a microorganism it divides to make more identical cells which makes lots of the right antibody to fight the infection
                      • some white blood cells stay in blood = MEMORY CELLS
                        • memory cells can produce very quickly if the same antigen enters the body for a second time
                          • fight of infection before you become iill
                            • = IMMUNE

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