Immune System

Immune System

1. Innate Immunity

   • Cells and Mechanisms present from birth The innate immune system provides an immediate but non-specific response.
   • barriers
     • Physical
       • Skin
         • low pH due to sweat and secretions inhibits bacterial growth
       • Mucous Membranes
         • traps harmful bacteria
         • Cilia prevents entry of organisms
     • Chemical
       • Stomach Acid
       • Enzymes
         • lysozyme
           • present in breast milk, tears, nasal secretions and saliva
     • Mechanical
       • Intermittant bladder emptying
         • flushes away organisms
   • Antimicrobial Substances
     • Interferons
       • produced by lymphocytes and macrophages during viral invasion
       • Involved in the activation on natural killer cells and macrophages
     • Complement
       • System involving proteins found in blood
         • When activated forms the complement cascade
           • Biochemical process where one component activates the next
             • Activated proteins provide protection from pathogens by promoting inflammation, chemotaxis and phagocystosis
     • Iron-binding Proteins
     • Antimicrobial proteins
   • Phagocytosis
   • Natural Killer Cells
     • 5-15% of Lymphocytes
     • Can recognise tumours cells and cells infected by viruses
     • Kill by releasing proteins that destroy cell membranes
   • What is it?
     • Present from birth
       • Does not improve
     • Immediate but non-specific response.
   • Acute Inflammatory Response
     • swelling
     • impaired function
     • tissues release histamine
       • promotes vasodilation
         • redness
         • heat
         • Increased capillary permeability
           • oedema
           • Pain
         • Increases flow of blood to the area
     • movement of leukocytes to the area by chemotaxis
       • known as diapedesis
     • Neutrophils phagocytose bacteria and small pieces of damaged tissue
       • Macrophages arrive and phagocytose greater quantities of bacteria and larger cells such as protozoa
     • Fibrinogen clots form around injury site
       • isolates area from healthy tissue

2. Adaptive (Specific) Immunity