IMMUNITY Ch.16 What is Immunity? Immunity is resistance to infection after a foreign antigen has penetrated the first line of defense, Immunity is achieved naturally, by having the disease or the artificial immunization. Immunity is acquired actively; that is, intentionally by receiving a vaccine or having had the diseases. Cont. What is Immunity? It may also be acquired in a passive manner, such as through breast milk or in vivo through the mother’s blood supply to the fetus. Natural and Acquired Immunities Natural acquired immunity – occurs when a person has been infected with a microorganism and recovers from the disease, has had a subclinical or very mild infection, and/or is a carrier of the microorganism. Artificial aquired immunity – results from having been immunized, or vaccinated, with a killed or attenuated microorganism. Immunities received in these instances produce active aquired immunity. Natural and Aquired Immunities Natural passive acquired immunity – is passed from mother to child across the placenta. Artificially acquired passive immunity – occurs when one receives gamma globulin, an antitoxin, or an immune serum. REMEMBER!!! Natural immunity is inherited and is permanent. Acquired or adaptive immunity is the reaction that occurs as a result of exposure to these invaders. Passive aquired immunity is borrowed immunity. It is aquired by injecting antibodies of other individuals or animals into a person’s body to protect him or her from a specific disease. Immunity’s Line of Defense Antibodies are produced in response to the presence of a foreign antigen, the infectious agent , a vaccine or an antitoxin. Antibodies produced in the bloodstream then protect the person against further exposure to the antigen. Antibodies are very specific and only act upon their corresponding antigen. Immunoglobulins Immunoglobulins are proteins that play an important role in antibody production. There are five classes each with a specific function IgG IgM IgA IgD IgE Immunoglobulins IgG – is the most abundant and can cross the placenta. IgM – is the largest, is confined to the blood and functions in agglutination reactions. IgA – is the predominant antigen found in tears, saliva, colostrum and intestinal secretions. Cont./ Immunoglobins IgD- works with IgM and is found on the surface of the B lymphocytes. IgE – is present in trace amounts in plasma, yet it is especially important in desensitizing allergic reactions. What are/is Antigens? Autoimmunity? Antigens are protein substances that, upon invasion of body, cause the immune system to produce antibodies to destroy that antigen. Autoimmunity occurs when one’s immune system goes awry and produces antibodies to its own, destroying those tissues. What is Hypersensitivity? Hypersensitivity occurs when the body’s immune system fails to protect itself against foreign material; thus allergies occur. Allergens are antigens that cause allergic reactions (e.g., grass, ragweed, pollen, penicillin). Severe allergic reactions can result in anaphylactic shock and even death. What are Toxins and Toxoids? Toxins are poisons produced by an organism. Toxoids are toxins that have been weakened by chemicals or heat, yet are still capable of antibody responses when injected.