Immune system and cells

Immune system and cells

1. Defence

   • Non-Specific
     • Physical barrier, Phagocytes
     • Immediate response
     • Same for all pathogens
   • Specific
     • Cell-mediated response (T-Lymphocytes), Humoral response (B-Lymphocytes)
     • Slower response
     • Specific to pathogens

2. Phagocytes and phagocytosis

   • Phagocytes: type of white blood cell, carries out phagocytosis
   • Response - Phagocytosis
     • Phagocyte detects foreign antigen on a pathogen
       • Phagocyte forms a vacuole and engulfs the pathogen (creates phagosome)
         • Lysosome fuses with phagosome, uses enzymes to break down pathogen
           • Phagocyte presents antigens on its surface

3. Antigens

   • Self-antigens: Molecules on the surface of our cells
   • Antigen (Non-self): Molecules on a pathogen that triggers an immune response

4. Specific Immune Response

   • Cell mediated Immunity (T-Lymphocytes/T-cells)
     • Mature in Thymus gland
     • Response
       • Phagocyte goes through phagocytosis and presents antigens
         • Helper T-Cell uses complementary shaped receptors and bind to the antigens
           • Helper T-Cell is activated and divides into three cells
             • More Helper T-Cells
               • Activate phagocytes
             • Cytotoxic T-Cells
               • Use perforin to punch holes in pathogen's membrane
             • Memory T-Cells
               • Used for a rapid response when the pathogen invades the body again
   • Humoral Response (B-Lymphocytes/B-Cells)
     • Mature in Bone Marrow
     • Antibodies
       • Globular proteins (Immunoglobulins)
         • 4 polypeptide chains
       • Specific to one type of pathogen
       • Binds to antigen to neutralise a pathogen
     • Response
       • Detects antigen and takes it in
         • Helper T-Cell attaches onto B-Cell and activates it
           • Divides by mitosis into two types of cells
             • Plasma cells
               • Secretes antibodies into the blood
             • Memory Cell
               • Used for a rapid response when the pathogen invades the body again

Images and files in the map