Immune System


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Immune System

  1. 1. Immunity
  2. 2. Nonspecific Defense <ul><li>Skin and Mucous Membranes </li></ul><ul><li>acid sweat pH 3  5 </li></ul><ul><li>enzyme in perspiration, tears, sweat, and saliva </li></ul><ul><li>lysozymes - attacks bacterial cell walls </li></ul><ul><li>respiratory tract contains cilia and mucus </li></ul><ul><li>digestion - acid in the stomach </li></ul>
  3. 3. Leukocytes <ul><li>neutrophils - chemotaxis - attracted by chemical signals </li></ul><ul><ul><li>self-destruct when destroying others </li></ul></ul><ul><ul><li>few day life span </li></ul></ul><ul><li>monocytes - morph into macrophages : longer lived </li></ul><ul><li>amoeboid cells - ingest bacteria, viruses, and cell debris </li></ul><ul><li>some bacteria have defenses to these </li></ul><ul><li>eosinophils - cytoplasmic granules with enzymes used against invaders – discharged </li></ul><ul><li>mainly attack parasites (worms) </li></ul><ul><li>natural killer cells - kill off infected cells of own body - very versatile in what attack </li></ul><ul><ul><li>recognize new/unusual proteins on the plasma membrane </li></ul></ul><ul><ul><li>more rapid response than other cells </li></ul></ul><ul><ul><li>may stop tumors and virus infestations </li></ul></ul><ul><ul><li>poke hole in plasma membrane - proteins called perforins </li></ul></ul><ul><li>plasma cells - produce Ab that are in blood </li></ul>
  4. 4. Antimicrobial Proteins <ul><li>complement - proteins that ID and dagger invaders </li></ul><ul><ul><li>interact with other defense mechanisms </li></ul></ul>
  5. 5. Antimicrobial Proteins <ul><li>interferon - virus infested cell (and activated lymphocytes and macrophages) </li></ul><ul><ul><li>releases substances that will improves nearby cell defenses </li></ul></ul><ul><ul><li>increase protein production that inhibit viral replication </li></ul></ul><ul><ul><li>especially for short term infection - cold and flu </li></ul></ul><ul><ul><li>activates phagocytes </li></ul></ul>
  6. 6. Interferons
  7. 7. Inflammatory Response - pain, heat and swelling <ul><li>damaged cells release prostaglandins, proteins, and K+ </li></ul><ul><li>vasodilation increase blood supply </li></ul><ul><li>histamines released (from mast cells or basophils) cause localized vasodilation </li></ul><ul><ul><li>prostaglandins also help this to happen </li></ul></ul><ul><li>heparin reduces clotting so new cells keep coming and cleansing </li></ul><ul><ul><li>later a clot forms to seal off and slow spread of pathogens </li></ul></ul><ul><li>increased temperature (increased blood flow) - activates/catalyzes enzymatic reactions of phagocytes </li></ul><ul><ul><li>may also denature foreign enzymes or proteins </li></ul></ul><ul><li>phagocytic cells migrate to area - via complement proteins and other factors </li></ul><ul><ul><li>1st = neutrophils: activation - increased metabolic activity </li></ul></ul><ul><ul><li>release H 2 O 2 and nitric oxide to kill of pathogens </li></ul></ul><ul><ul><li>invade then die </li></ul></ul><ul><li>macrophages remain to protect </li></ul><ul><ul><li>may get pus from dead cells and fluid during clean up </li></ul></ul><ul><ul><li>severe infection  systemic response </li></ul></ul><ul><ul><li>bone marrow releases more neutrophils </li></ul></ul><ul><ul><li>increase leukocytes </li></ul></ul><ul><li>fever - due to pathogens or proteins called pyrogens that re-set temp for battle </li></ul>
  8. 8. Lymphatic System - tissues and free cells <ul><li>Cells = T cells (thymus-dependent) cells, B cells (bone marrow derived) and Natural Killer cells </li></ul><ul><li>lymph node = lymph tissue wrapped in fibrous CT </li></ul><ul><li>percolate out unwanted - capture cancer cells </li></ul>
  9. 9. Temperature <ul><li>fever - stimulates phagocytosis </li></ul><ul><li>inhibits microbial growth </li></ul><ul><li>reduces Fe that bacteria need </li></ul><ul><li>speeds up tissue repair </li></ul>
  10. 10. Specific Response <ul><li>T Cells – start in bone marrow  thymus where mature </li></ul><ul><ul><li>Cell mediated response </li></ul></ul><ul><ul><li>ID via antigens produced </li></ul></ul><ul><ul><li>Several kinds of effector cells </li></ul></ul><ul><ul><li>Helper - initiate humoral and cell mediated response </li></ul></ul><ul><ul><li>stimulate activation of both T cells and B cells </li></ul></ul><ul><ul><li>Cytotoxic - lyse cell infected w/ virus or cancer </li></ul></ul><ul><li>production of cell mediated immunity </li></ul><ul><li>some serve as memory </li></ul><ul><li>no response on first exposure, but many made for next time </li></ul><ul><li>Natural Killer cells = lymphocytes </li></ul><ul><ul><li>surveillance of cells </li></ul></ul><ul><ul><li>attack foreign cells, viral infected cells and cancer cells </li></ul></ul><ul><ul><li>Inducer – development of T cells in thymus </li></ul></ul><ul><li>B Cells - bone marrow </li></ul><ul><ul><li>Humoral response or Ab response </li></ul></ul><ul><ul><li>ID antigen and the start to reproduce --> plasma cells (= effector cells) </li></ul></ul><ul><ul><li>which secrete Ab’s that flag antigens for destruction </li></ul></ul>
  11. 12. Strategies <ul><li>Innate immunity - genetically determined </li></ul><ul><ul><li>people not susceptible to same diseases as gold fish </li></ul></ul><ul><li>Active immunity - after exposure to an antigen </li></ul><ul><ul><li>own immune system - has many capabilities these are stimulated after exposure </li></ul></ul><ul><li>Natural from infection - starts to develop after birth </li></ul><ul><ul><li>develops on an as needed basis </li></ul></ul><ul><li>Artificial (Induced) - deliberate exposure </li></ul><ul><ul><li>from vaccination/immunization </li></ul></ul><ul><ul><li>and the forced version: where your Mom forced you to play with the kid with chicken pox so you could develop immunity </li></ul></ul><ul><li>Passive immunity - Ab from one individual to another </li></ul><ul><ul><li>usually short lived </li></ul></ul><ul><ul><li>example mother to fetus - across placenta, in milk </li></ul></ul><ul><ul><li>can also be artificial (induced) </li></ul></ul>
  12. 13. Humoral response <ul><li>Ab immune response to toxins, bacteria, and viruses </li></ul><ul><ul><li>Ab production from lymphocytes, carried on B cells plasma membrane </li></ul></ul><ul><ul><li>if antigens bind to Ab then the B cells are sensitized </li></ul></ul><ul><ul><li>sensitized B cell encounter an already activated helper T cell </li></ul></ul><ul><ul><li>B cells then usually --> mitosis --> plasma cells and memory B cells </li></ul></ul><ul><li>Memory B cells --> 2nd exposure --> mitosis </li></ul>
  13. 14. Ab aid to destroy antigens <ul><ul><li>Neutralize - land on specific site on pathogens needs to enter host cells </li></ul></ul>
  14. 15. Ab aid to destroy antigens <ul><ul><li>Agglutination and precipitation - form bridges between two pathogen cells </li></ul></ul><ul><ul><li>Ab can bind on two spots - tips of Y </li></ul></ul>
  15. 16. Ab aid to destroy antigens <ul><ul><li>Activate complement - when bound to antigen </li></ul></ul><ul><ul><li>change in shape so compliment proteins bind </li></ul></ul><ul><li>complements = proteins that supplement the action of Ab’s </li></ul><ul><li>destroy target cell’s plasma membrane - create a pore </li></ul>
  16. 17. Ab aid to destroy antigens <ul><li>stimulate inflammation - basophils and mast cells </li></ul><ul><li>attract phagocytes - neutrophils and macrophages </li></ul><ul><li>makes target easier for macrophages to engulf </li></ul><ul><li>gives phagocytes something to hang onto </li></ul><ul><li>vs slick cell membrane of some bacteria </li></ul><ul><li>Attract phagocytes - eosinophils, neutrophils, macrophages </li></ul><ul><li>Prevents bacteria and viral adhesion </li></ul><ul><li>makes it hard for pathogens to attach </li></ul>
  17. 18. Cell mediated response <ul><li>attack viruses, abnormal cells, bacteria, fungi, protozoans, worms, </li></ul><ul><li>transplant tissues, cancer cells </li></ul><ul><ul><li>T cell activation - before immune response must activate by exposure to antigen </li></ul></ul><ul><li>Major histocompatibility complex (MHC) glycoprotein self markers </li></ul><ul><li>unique to each individual </li></ul><ul><li>MHC Class I: membranes of all nucleated cells, from golgi </li></ul><ul><li>if abnormal peptides are present  T cell activated </li></ul><ul><li>common for viruses to bind here </li></ul><ul><li>MHC Class II: found only in Antigen presenting cells </li></ul><ul><ul><li>= all monocytes/phagocytes = microglia, in CT, in liver </li></ul></ul><ul><li>T cells are specific to an antigen - only activated to certain antigens </li></ul><ul><li>Memory - based upon memory cells from 1st infection </li></ul><ul><li>1st immune response = increase lymphocytes to form clones of effector cells </li></ul><ul><li>2nd immune response = faster, Ab more effective at binding to antigen </li></ul><ul><li>from second time infected </li></ul>