immunity
- Created by: kierasanghera
- Created on: 25-05-16 11:24
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- immunity
- non specific response
- always works in the same way regardless of the pathogen
- many are barriers
- make up our primary defence mechanisms
- skin
- made up of protein heratin effective barrier against pathogens
- mucus membrane
- goblet cells and ciliated epithelium to trap and remove pathogens
- stomach acid
- PH2 destroys pathogens entering, enzymes and proteins denatures by low PH
- tear ducts
- secrete substances containing enzymes to break down bacteria
- second line of defence
- phagocytosis
- neutrophils and monocytes
- engulf and digest non self particles ' bacteria and viruses'
- body cells damaged by bacteria etc. release cytokines which will attract phagocytes to the area
- bacteria will have different surface proteins (antigens) so are recognised as non self
- neutrophils and monocytes
- phagocytosis
- inflammation
- damaged tissues release histamine
- this causes widening of arterioles in this area
- causes more blood to flow to that area and increases temp
- capillaries become more permeable, so more tissue fluid escapes, which causes swelling
- more phagocytes delivered to the area to deal with any bacteria that could cause infection
- third line of defence
- antibodies
- 4 polypeptide chains, two heavy and two light
- constant region is the same for all antibiodies
- variable region different for each type
- variable region allows antibody to attach to a specific pathogen and destroy it
- antibodies are quaternary proteins
- lymphocytes
- Bl lymphocytes
- each capable of producing a separate antibody
- when a pathogen enters the body on type of b lymphocyte will have the receptors matching to the antigens on the pathogens surface, thin takes time to find
- when the b lymphocyte is found it will divide by mitosis in a process called clonal expansion
- some become plasma cells (to deal with the pathogen
- some become memory cells which remain in the body for long periods of time in case the pathogen enters again
- t lymphocytes
- cloned t lymphocytes differentiate into three types
- t killer
- kill any body cells infected with the virus (release chemicals to show they are damaged)
- t helper
- secrete cytokines which carry out cell signalling which stimulates further phagocytes and stimulates b lymphocytes to produce more antibodies and stimulates continued division of t killer cells
- t supressor
- nhibit immune response once the pathogen has been dealt with
- t killer
- cloned t lymphocytes differentiate into three types
- Bl lymphocytes
- agglutination:hold the bacteria close together so that they clump making it easier for phagocytes to engulf them
- precipitation:causes soluble antigens on the pathogen to precipitate making them easier to engulf
- neutralisation:antibodies can bind to the toxins and neutralise them
- lysis : antibodies can attract enzymes to the pathogen to break them down
- opsonins attach to the pathogens specific binding site and attach to a phagocyte on the other end which holds it nearer making it easier to engluf
- antibodies
- primary response is slow because it takes time for clonal selection and expansion
- secondary response is fast due to memory cells recognising the pathogen
- leads to immunity
- secondary response is fast due to memory cells recognising the pathogen
- non specific response
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