Basic Immunology The Immune system must have the ability to distinguish between self and non-self molecules Self Molecules- components of an organism’s body that can be distinguished from foreign substances by the immune system. Autoimmunity- immune reaction against self molecules Non-self Molecules- recognized as foreign molecules Ex: Antigen (short for antibody generators) Immune System: Responsible for protecting the animal from potentially harmful organisms attempting to invade the body.

Pathogen: virus, bacteria, fungi, parasites, etc. that can do harm to the body Non-specific (Innate) Immunity 1 st line of defense: skin, mucous membranes, stomach acid 2 nd line of defense: inflammatory response (bringing blood, fluid and cells to the site to fight off the pathogen); phagocytes (a type of white blood cells that can engulf and eat up foreign matter that it knows is bad to the body) Vaccination: administration of antigen (vaccine) to stimulate a protective immune response against a specific infectious agent (aka: immunization) Immunity: the state of being resistant to a specific disease. Different forms of immunity are obtained during life.

Antigen: substance that the body regards as foreign and may be capable of stimulating an immune response. Antibodies: disease or infection-fighting proteins produced by the body in response to the presence of a specific antigen. Specific /Adaptive Immune System ~ Naturally Acquired Passive Immunity: immunity resulting from transfer of antibodies from one animal to another through mother to offspring either before birth or in colostrum (first milk of newborn). Naturally Acquired Active Immunity: resistance to a specific disease after the development of antibodies during the actual disease Artificially Acquired Passive Immunity: resistance to a specific disease by receiving antiserum-containing antibodies from another host Artificially Acquired Active Immunity: resistance to a specific disease through vaccination

Immunology: study of the immune system Lymphocytes: type of white blood cells that are involved in the immune response and work against specific agents. They are formed in the bone marrow and grow in lymphatic tissue throughout the body, such as bone marrow. Two categories of lymphocytes are: T cells: (thymus-dependent) responsible for cell-level immunity and direct attack the invading antigen. Most effective against viruses that infect the body cells, cancer cells, and foreign tissue cells. B cells: (bone marrow-derived) produced and mature in bone marrow and make antibodies that react with the antigen. Most effective against bacteria, viruses, and toxins. Also involved in allergic reactions. The immune system is activated when the 1 st line of defense fails.

7 Lymphatic System  One way system: to the heart  Return of collected excess tissue fluid  Return of leaked protein  “Lymph” is this fluid  Edema (build-up of fluid) results if system blocked or surgically removed

8 The Immune System  Recognizes specific foreign molecules  Each exposure (to the same pathogen) increases the effectivity of the response  Lymphoid organs  Lymph nodes-small, bean-shaped structures; filter lymph and store B and T lymphocytes. Filter lymph to remove harmful substances (bacteria/viruses). Swollen lymph nodes sign of sickness.  Spleen- located in abdomen; filters foreign material from blood, stores red blood cells, maintains balance of cells and plasma in blood.  Thymus- Found in young animals (disappears as animals age) in thoracic cavity. Develops T cells.  Tonsils- tissue that protect nose and upper throat.