15. Body Defenses Against Infection Antigen – any foreign substance in the body Pathogen – any foreign substance that causes a disease Types of Defense Mechanisms 1. Nonspecific - can kill many pathogens 2. Specific - kills only one type of pathogen - also called immunity
16. Nonspecific Resistance 1. Species Resistance - a species may be naturally resistant to a disease that may affect other species 2. Mechanical Barriers - pathogens unable to penetrate through - ex. skin and mucus membrane
17. 3. Chemical Barriers - enzymes that destroy pathogens - ex. pepsin in stomach lysozyme in tears and mucous - interferon – responds to viruses and tumor cells to interfere with their reproduction
18. 4. Natural Killer (NK) Cells - defend against viruses and cancer cells by secreting perforins that splits those cells open 5. Inflammation - localized redness and swelling - help control pathogens by phagocytosis - body fluid & WBC’s collects here, begins to clot, prevents the spread of pathogens to nearby tissues
19. 6. Phagocytosis - mostly carried out by neutrophils and monocytes develop into macrophages 7. Fever - elevated body temperature - causes the liver & spleen to absorb iron, thereby reducing the iron needed by the bacteria for reproduction
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38. Specific Resistance – Immunity resistance to specific foreign agents Origin of Lymphocytes - originate in red bone marrow and released into blood - ~½ reach thymus - become differentiated - called T-lymphocytes or T-cells - other half differentiate elsewhere - called B-lymphocytes or B-cells
39. Functions of Lymphocytes - T-cells can attach to antigens directly called cell-mediated immunity - T-cells provide defense against viral infections by destroying the cells a virus is in - B-cells produce antibodies which will attach to and deactivate specific antigens antibody-mediated immunity
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41. Types of Antibodies Immunoglobulins secreted by B-cells 5 TYPES 1. Immunoglobulin G (IgG) - can digest cell membranes or alter the cell membrane for phagocytosis 2. Immunoglobulin A (IgA) - helps control respiratory viruses and digestive disturbances
42. 3. Immunoglobulin M (IgM) - found in blood plasma - responds to antigens in foods - responds to bacteria - anti-A and anti-B are this type 4. Immunoglobulin D (IgD) - important in activating B-cells 5. Immunoglobulin E (IgE) - associated with allergic reactions
43. Types of Immunity 1. Naturally Acquired Active Immunity - immune because of having the disease 2. Artificially Acquired Active Immunity - a vaccination that contains a dead or weakened virus 3. Artificially Acquired Passive Immunity - receive an injection of artificially made antibodies 4. Naturally Acquired Passive Immunity - antibodies passed from mother to child through placenta or breast milk
44. Allergic Reactions 1. Delayed Reaction Allergy - results from repeated exposure to skin due to chemical contact - T-cells become activated and collect at the skin - causes inflammation of the skin
45. 2. Immediate Reaction Allergy - involves activation of B-cells - antigens are called allergens - IgE causes basophils to release histamine and serotonin - causes the dilation of blood vessels, swelling of tissues, contraction of smooth muscles - usually T-suppresser cells suppress a severe response - in some people, they do not function properly, can cause death
46. Transplantation & Tissue Rejection - a transplanted organ is from someone else - body recognizes it as a non-self substance - body begins to reject it - rejection can be reduced by matching donor and recipient and administering imminosuppressant drugs
Notas del editor
Hookworm
Babeosis – microscopic parasite infecting red blood cells Asymtomatic to lethal
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