Unit 4 - Definitions & processes

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katemacleod
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Key areas 4.1and 4.2. unit 4 is green

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natural killer cell -a specialized white blood cell -releases cytokines which stimulate the specific immune response -induce viral infected cells to destroy itself by apoptosis -Causes the production of digestive enzymes inside the viral infected cell
Inflammatory response -caused by the release of h i s t a m i n e by m a s t cells -this causes 1. vasodilation of arterioles which increase blood flow 2. increased capillary permeability -increased blood flow and secretions of cytokines leads to 1. an accumulation of p h a g o c y t e s 2. delivery of antimicrobial proteins (to kill bacteria) 3. delivery of clotting elements which form a clot (to prevent microbes entering the bloodstream)
epithelial cells -form a physical barrier to prevent entry of pathogens (skin) -produce secretions against infection (mucus in trachea, lysozome in tears, acid in the stomach)
phagocytes -a specialised white blood cell -releases cytokines which stimulate the specific immune response -recognise surface antigen molecules on pathogens and d e s t r o y them by phagocytosis
phagocytosis when a phagocyte e n g u l f s a pathogen
immune surveillance???? -a range of white blood cells constantly circulate tissues for signs of infection or damage -if tissues become damaged or invaded, cytokines are released increasing blood flow -results in specific white blood cells accumulating at the site of infection or damage
clonal selection theory -lymphocytes have a single type of membrane receptor which is specific for one antigen -antigen binding leads to repeated lymphocyte division resulting in a clonal population of lymphocytes
lymphocytes -all cells have proteins on their surface called antigens -the immune system can tell the difference between self and non-self antigens -l y m p h o c y t e s respond specifically to antigens on f o r e i g n cells
foreign cells cells infected by pathogens toxins released by pathogens?
pathogens phagocytes bad good
immunological memory -some t and b lymphocytes survive long term as memory cells -a secondary exposure to the same antigen rapidly gives rise to a new clone of lymphocytes -a rapid and greater immunological response 2nd time
t-lymphocytes -they have specific surface proteins so they can tell the difference between self and non-self antigens -some can destroy infected cells by inducing apoptosis -some secrete cytokines that activates B-lymphocytes & phagocytes
what else do t-lymphocytes do? -when pathogens infect tissues, some phagocytes capture the pathogen & display its fragments of its antigens on their surface -these antigen presenting cells (APC) activate the production of a clone of t-lymphocytes that move to the site of infection (under the direction of cytokines)
b-lymphocytes (part 1) each b-lymphocyte clone produces a specific antibody molecule that will recognize a specific antigen surface molecule on a pathogen or toxin
b-lymphocytes (part 2) -Antibodies are Y-shaped proteins which bind to their specific surface antigen -antigen/antibody complexes may 1. i n a c t i v a t e a pathpgen or toxin or 2. render it more susceptible to pahagocytosis or 3. stimulate a response causing cell lysis
b-lymphocytes (part 3) b-lymphocytes (activated by antigen presenting cells and t-lymphocytes) produce a clone of b-lymphocytes that secrete antibodies into lymph and blood where they may make their way to the infected area??
immune system problems-auto immune disease & allergy -I.S. regulation failure leads to auto immune disease - this is when t-lymphocytes respond to self-antigens -allergy is a hypersensitive b-lymphocyte response to an antigen that is normally harmless
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