The Immune System Chapter 43

Nonspecific Immunity  Helps prevent the entry of microbes: Skin and mucus membranes – 1 st line of defense Skin and mucus membranes – 1 st line of defense Acidify the skinAcidify the skin Saliva, tears – have antimicrobial proteinsSaliva, tears – have antimicrobial proteins Nostril hairs & mucusNostril hairs & mucus Stomach acidsStomach acids  Helps prevent the spread of microbes: Phagocytes – destroy themselves and pathogen Phagocytes – destroy themselves and pathogen Inflammatory response – brings blood and therefore more phagocytes to the area Inflammatory response – brings blood and therefore more phagocytes to the area  Antimicrobial proteins – either directly attack microbes or interfere with their reproduction

Specific Immunity  The body responds to a particular type of infectious agent  Four components: Specificity Specificity Diversity Diversity Memory Memory Self/non-self recognition Self/non-self recognition  Lymphocytes provide the specificity of the immune system

Specificity  The immune system is able to recognize and eliminate particular microorganisms and foreign molecules  This is the job of the lymphocytes  Antigen – a foreign substance that elicits a specific response by lymphocytes  Antibody – an antigen-binding protein produced by lymphocytes that functions as the effector in an immune response; these tag the invading cell for destruction

Diversity  The ability to respond to the wide variety of antigens which enter the body is based on the diversity of antigen-specific lymphocytes present in the system  The primary immune response is the making of lymphocytes during the 1 st exposure to the antigen  A secondary immune response occurs when the body is exposed to the antigen again

Memory  The ability to recognize a previously encountered antigen  This is based on memory cells which are produced during the primary immune response  Memory cells are not active during the primary response but survive in the system for a long time  This is acquired immunity

Self/non-self recognition  The immune system is able to distinguish between the body’s own molecules and foreign antigens  It develops before birth when the lymphocytes begin to mature  The failure of this ability to recognize self leads to autoimmune disorders that destroy the body’s own tissues

Blood groups and transfusion  An example of self/non-self recognition  Type A blood – produces A antigen; makes B antibodies  Type B blood – produces B antigen; makes A antibodies  Type AB blood – produces A and B antigen; makes neither A nor B antibodies  Type O blood – produces neither A nor B antigen; makes both A and B antibodies  Universal donor – Type O: no antigens  Universal recipients – Type AB: no antibodies

Immune Response: either humoral or cell-mediated  Humoral immunity – antibodies produced in response to toxins, bacteria, and viruses present in the body fluids (the ‘humors’)  Cell-mediated immunity – the response to intracellular bacteria, viruses, fungi, protozoa, worms, transplanted tissues, and cancer cells

Achieving Immunity  Active immunity – conferred by recovery from an infectious disease Depends on response by the person’s own immune system Depends on response by the person’s own immune system May be acquired through illness or vaccination May be acquired through illness or vaccination  Passive immunity – transferred from one person to another Pregnant or nursing mother to child Pregnant or nursing mother to child Artificially from an animal or another person already immune to the disease Artificially from an animal or another person already immune to the disease

Abnormal immune function  Allergies – a hypersensitivity to an environmental antigen Anaphylactic shock – a life-threatening condition associated with some allergens such as insect stings or peanuts; epinephrine may be used as an anecdote Anaphylactic shock – a life-threatening condition associated with some allergens such as insect stings or peanuts; epinephrine may be used as an anecdote  Autoimmune disorders – an immune system reaction against self lupus erythematous, rheumatoid arthritis, multiple sclerosis, insulin-dependent (‘juvenile’) diabetes -? lupus erythematous, rheumatoid arthritis, multiple sclerosis, insulin-dependent (‘juvenile’) diabetes -?  Immunodeficiency diseases – immune system is not working Hodgkin’s disease Hodgkin’s disease AIDS AIDS