THE IMMUNE SYSTEM

THE IMMUNE SYSTEM

1. ADAPTIVE IMMUNE RESPONSE

   • THIRD LINE OF DEFENCE
     • Once pathogen is identified by immune system lymphocytes launch specific responses including the production of antibodies
   • Specific to the identified pathogen
   • CELL LINES OF ADAPTIVE IMMUNITY
     • This table below clearly summarises the 2 cell lines of adaptive immunity
       • CLONAL SELECTION
         • Explains how lymphocytes can respond to a large and unpredictable range of antigens
     • T CELLS DELIVER THE CELL MEDIATED DEFENCE
       • B CELLS DELIVER THE HUMORAL IMMUNE DEFENCE
         • by secreting antibodies that bind to surface antigens on pathogens and label them for elimination; antibodies also bind to soluble toxins.
         • PRODUCE ANTIBODIES
           • 4 polypeptide chains, Y Shaped
       • Include the direct elimination of pathogen-infected cells and other abnormal cells, such as cancer cells.

2. INNATE IMMUNE RESPONSE

   • FIRST LINE OF DEFENCE
     • Physical barrier to entry of pathogens,
       • Skin
       • Secretions Tears wash contaminants
   • SECOND LINE OF DEFENCE
     • A range of defence mechanisms inside the body to inhibit or destroy pathogens
     • HUMORAL RESPONSE TO PATHOGENS
       • The actions of soluble active molecules. Key soluble molecules involved in innate immunity include proteins known as complement and interferons.
   • Protects against a broad range of non specific pathogens by containing the infection through inflammation
   • NATURALLY ACQUIRED
     • ACTIVE
       • Antigens enter the body naturally, body produces antibodies and lymphacytes
     • PASSIVE
       • Antibodies pass from mother to foetus
   • PHAGOCYTOSIS
     • PHAGOCYTIC CELLS OF INNATE IMMUNE SYSTEM
       • MACROPHAGE
         • Large, Efficient, Stretches to engulf pathogens
       • NEUTROPHIL
         • Contain toxic substances that kill or inhibit bacteria pathogens
       • DENDRITIC CELL
         • In tissue in contact with external environment and acts as messenger between innate and adaptive system by presenting antigen materials to T cells of immune system
       • OTHER CELLS AND PROCESSES
         • MAST CELLS
           • Contain histamine involved in inflammation and allergic responses
           • INFLAMMATION
             • 1. Destroy cause of infection and remove it
             • 2. If 1 fails, confine infection to small area to limit effects
             • 3. Replace or Repair tissue damaged by infection
         • COMPLEMENT PROTEINS
           • -Phagocytosis, -Attracting Neutrophils and Macrophages to infection site,-Rupture membranes of foreign cells
     • Process of eliminating pathogens by engulfment

3. LYMPHATIC SYSTEM

   • Circulate defensive white blood cells through the fluid transported
     • LYMPHATIC SYSTEM IN IMMUNITY
       • Lymphocytes in circulation constantly move between sites where antigens may be encountered, these antigens are presented to the T cells in secondary lymphoid tissue
         • Antigen recognition leads to activation of T and B cells increasing the number of lymphocytes
   • Shows the network of tissues and organs that collect the tissue fluid leaked from blood vessels and return it to heart

4. ACQUIRED IMMUNITY

   • ARTIFICIALLY ACQUIRED
     • ACTIVE
       • Antigens are introduced in vaccines, the body produces antibodies and becomes immunised
         • VACCINATION
           • Vaccination is the administration of antigenic material (a vaccine) to stimulate an individual's immune system to develop adaptive immunity to a pathogen. Vaccines can prevent or ameliorate morbidity from infection.
           • TYPES OF VACCINATION
             • SUBUNIT VACCINE
               • Produce immune response
             • HERD IMMUNITY
               • HIGH: Most of the population are immunised spread is limited
               • LOW: Only a small proportion are immunised, disease spreads rapidly
             • WHOLE AGENT VACCINE
               • Whole organisms
     • PASSIVE
       • Preformed antibodies in an immune serum are introduced by injection
   • Resistance to specific pathogens acquired over the lifespan

5. AUTO IMMUNE DISEASES

   • Result of body's immune system attacking itself
     • Type 1 diabetes, Multiple Sclerosis, Rheaumatoid Arthritis
   • HIV: Immunodeficiency virus infects lymphocyte cells
     • No cure, antibiotics can slow progression
     • Can lead to AIDS, immune system unable to fight off infections, T cells destroyed

6. ANTIGENS

   • Substance capable of producing immune response
   • TYPES OF ANTIGENS
     • NON SELF
       • Foreign material provoking immune response
       • MHC MARKERS
         • MHC 1: Present antigenic fragments from intracellular
         • MHC 2: Present antigenic fragments from outside the cell
     • SELF
       • Self Tolerance System Failure
     • ALLERGENS
       • cause allergic reaction

7. PATHOGENS

   • Infectious agents that spread between hosts and cause diseases
     • CELLULAR
       • Living Organisms, can carry out life process and reproduce
         • Bacteria, Fungi,Protozoa
     • NON CELLULAR
       • Non Living, make use of hosts metabolism
         • Viruses, Prions

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