Immunological defense systems
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Transcript of Immunological defense systems
IMMUNOLOGICAL DEFENSE MECHANISMS
Presented by: Miss Sefakor Agbenyegah
MPhil Biochemistry(4575215)
http://www.was-ist-antiaging.de
IMMUNOLOGY Study of biological mechanisms used by larger
organisms to protect themselves against invasion by other organisms
Immune – having a high degree of resistance to a particular disease or infection
Immune system – biological mechanism for identification and elimination of pathogens in a larger organism
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DEFENSE MECHANISMS Physical, chemical and biological properties of an
organism which reduce its susceptibility to foreign organisms/ materials
Three lines of defense – First, second and third lines
Generally classified under specific or non-specific
Non-specific mechanisms repel all microbes equally
Specific mechanisms are tailored for particular microbes
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LINES OF DEFENSE MECHANISMS01/05/2023
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FIRST LINE OF DEFENSE 01/05/2023
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FIRST LINE OF DEFENSE CONT’D Mechanical – cilia, mucous membranes,
Chemical – lysozyme, pH, lactate, defensins
Biological – normal flora,
Reflexes – vomiting, diarrhoea, coughing, sneezing,
SECOND LINE OF DEFENSE Cellular counterattack – when first line is evaded Involves two major classes of defenses:
Cellular defenses Molecular defenses
Cellular defenses: Inflammation Phagocytosis Natural killer cells activity Fever Blood clotting
Molecular defenses: Complement proteins Cytokines
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PHAGOCYTOSIS
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NATURAL KILLER CELLS Lymphocyte-like cells with granular cytoplasm Attack and phagocytize
Already invaded cells Cancer cells
FEVER: May be triggered in a large-scale infection
Role of fever: inhibits microbial multiplication by reducing
blood levels of iron speeds up body repair processes
High fevers may however be dangerous
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MOLECULAR DEFENSES Cytokines
Block viral replication using interferons trigger the inflammatory response elevation on the body temperature activate NK cells and macrophages
Complement proteins About 30 different inactive proteins that circulate in
the blood produced by the liver Involved in opsonization Attract phagocytes by chemotaxis Promote inflammation Punch holes in membrane of bacteria
THIRD LINE OF DEFENSE Made up of cells and chemicals which attack specific
antigens An antigen is a protein molecule that provokes
specific immune response in the body May be antibody-mediated (humoral immunity) or
cell-mediated Involves lymphocytes, macrophages and dendritic
cells Slow response; Exposure results in immunologic
memory by T and B lymphocytes
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REFERENCES Zabriskie, J. B., (2010). Essential clinical
immunology, Cambridge University Press, pp. 34-40; 111
Kim, Y. J., (2014). Autoimmunie diseases, A rising epidemic, Medicine, pp 15-20
Silverstein, A., (2001). Autoimmune diseases, Nat. Immunol. 2, 279-281.
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THANK YOU