Immune System

Immune System

Immune Response
1. Defence Mechanisms
  1. Non specific
    1. Physical Barrier
      1. Skin
    2. The Process
      1. Phagocytes engulf pathogens
        Phagocytosis
        Phagocyte Type of WBC
        Phagocytes eg macrophage in liver
        Phagocyte recognises foreign by binding to receptors
        Chemical proporties of pathogens also act as attractants for phagocytes
        Cytoplasm of phagocyte moves around the pathogen to engulf it forming a phagosome
        Pathogen contained in a phagocytic vacuole in the cytoplasm
        Lysosome containing lysozymes fuse with P.vacuole
        Hydrolytic enzymes start to hydrolyse pathogen cell walls
        Soluble products absorbed / removed from cell by exocytosis
        The foreign antigens presented on its cell surface membrane
        Turns into Antigen-presenting cell APC
        Antigen-presenting phagocytes activate helper T cells
        T lymphocyte cell specific receptors bind to Antigens on the APC
        Attachment triggers T lymph cell to divide rapidly by mitosis to form its clone
        Cloned T cells do many things:
        Activate cytotoxic T cells
        Kill abnormal cells (phagocytes) infected by pathogen
        Binds to pathogen to start cell death
        Produces Hydrogen peroxide OR protein (perforin)
        This makes holes in cell-surface membrane
        Resulting in cell death
        T helper cells
        Stimulate B cells
        T-memory cells
        Remembers specific antigen of pathogen
        T lymphocytes activate B lymphocytes
        Another type of WBC
        B-Plasma cells release more antibodies into blood
        Identical to B cell (clones)
        Secrete many specific antibodies
        Monoclonal antibodies
        Responsible for immediate defence
        Production of anitbodies and memory cells
        Primary Immune Response
        B-Memory Cells keep antibodies
        B-memory cell remembers
        specific antibody for 2nd response
        B cells covered in antibodies
        Antibodies bind to their specific antigens or receptors on T cell
        Forms antigen-antibody complex
        This process and helper T cells activates B cells
        Activated B cells divide into plasma cells
        B cells can also be a APC
        Antibody on B cell surface fits to complementary foreign antigen
        Antigen enters B cell by endocytosis and is presented
        T cell binds to presented antigen
        Activates B cell to divide
        Process called clonal selection
  2. Specific
    1. Cell-mediated response
      1. T lymphocytes (T cells)
        Type of WBC
        Recognising "self"
        Fetus
        Lymphocytes collide with self material exclusively
        Any lymphocytes that receptors fit with self material die or are suppressed
        Adult
        Lymphocytes produced in bone marrow
        They initially only encounter self-antigens
        Any that show immune response to self-antigens undergo apoptosis (cell death)
        This eliminates any clones of these before they appear in the blood
    2. Humoral response
      1. B lymphocytes (B cells)
2. Cell Recognition
  1. Antigens
    1. Proteins
      1. Variety and specific structures cause many combination
    2. Membrane-bound protein, WBC can identify antigens determine self or foreign
  2. Identifying the body's own cells and molecules
    1. "self"
  3. Identifiying foregin cells and molecules
    1. "non-self"
3. Foreign antigens trigger an immune response
Antibodies
1. Protein with quaternary structure
  1. Arms of antibodies bind to antigens of different pathogens
    1. Clumps pathogens together (agglutination)
      1. Effective as
        Limits the spread of the pathogen
        Spread of pathogen around the body
        Clumps for effective phagocytosis

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	Erstellt von Dominic Weston vor etwa 7 Jahre