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Lymphatic System & Immunity
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Vocab -gen: be produced Humor-: fluid Nod-: knot Immun-: free Inflamm-: set on fire Patho-: disease Lymph: the fluid inside lymph vessels and capillaries
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Lymphatic System The lymphatic system: A collection of cells and biochemicals that travel through lymph vessels, organs and glands
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Functions Launch immune attacks against foreign particles Protects against toxins and cancer Filters blood plasma
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Pathways Begin at capillaries and merge with larger vessels Capillaries → Vessels → lymph nodes → lymph trunks → ducts
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Lymph Nodes Lymph nodes: specialized glands that contain lymphocytes B & T cells of the immune system Macrophages that kill microorganisms found all over the body except in the nervous system Functions: Filters harmful particles from lymph Immune surveillance= lymphocytes attack viruses, bacteria and parasites
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Lymphatic System Hilum- where blood vessels and nerves join a lymph node Lymphatic trunks: collecting ducts that receives lymph fluid from distal parts of the body
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Lymphatic System Lymph Modules: the functioning unit of a lymph node Lymph Sinuses: a network of chambers in a lymph node
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Lymph Movement One way Exercise and movement increase lymph flow Breathing stimulates lymph movement Impaired lymph movement: Causes edema (swelling)
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Lymphatic System Thymus= a soft gland located posterior to the sternum Large when you are born – shrinks when you get older Secretes lymphocytes and hormones
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Spleen The largest organ in the lymphatic system Filled with blood vessels, not lymph Contains lymphocytes and macrophages Filters blood as much as lymph nodes do
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Defense Against Infection Pathogen: disease-causing agent virus, bacteria, fungus
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Nonspecific (innate responses) Inflammation= swelling, heat, pain, redness and pus Fever= makes body inhospitable to pathogens Phagocytosis= digests foreign material Chemical barriers= body fluid, stomach acid, (low pH) mechanical barriers= skin, mucus membranes, hair, sweat Species resistance= organism can’t survive in human body Natural killer cells= cells that secrete cytolytic (“cell cutting”) substances that cut through cell membranes
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Specific Immune Responses Specialized cells recognize foreign invaders Respond more slowly than non-specific responses Antigens= proteins, sugars or lipids on a cell’s surface recognize foreign invaders
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Lymphocytes T cells: require antigen-presenting cells to be activated Enter tissues and Kill foreign invaders Have a memory once exposed to a pathogen
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Lymphocytes B-cells: activated by specific antigens or T-cells Have a memory once exposed to a pathogen Never enters tissues Produce antibodies
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Antibodies Immunoglobins: present in plasma, interstitial fluid, breast milk, tears, bile, stomach acid, nasal mucus, urine Act on allergens, bacteria, viruses, fungus and toxins Reaction to antigens: Tries to contain the pathogen or toxin to the area it is in direct attack, stimulate inflammation, or activate cells to act
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Allergic Reactions Allergic reactions: an immune response to a non- harmful substance can damage tissues Allergens: antigens that cause allergic reactions
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Allergic Reactions Immediate-reaction allergies: within minutes of contact with allergen Activates B-cells Release histamines and prostaglandins that: Causes blood vessel dilation Swelling Increased mucus production Contraction of bronchial muscles
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Transport/Tissue Rejection Transplant/Tissue Rejection: donor part is recognized as an invader and the body reject it Immunosuppressive drugs: used to reduce the chance of tissue rejection Interfere with immune response by suppressing T-cells and antibody formation
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Auto Immunity Auto immunity: immune system turning against itself Autoantibodies: attack tissues and organs Examples: type 1 diabetes, mellitus, rheumatoid arthritis, lupus Caused by: Viruses T-cells not “learning” to recognize other threats Genetics
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Active Immunity Naturally Acquired: exposure to pathogens stimulates immune response ex: chicken pox Artificially Acquired: a vaccination containing weak or dead pathogens is given to stimulate an immune response ex: polio vaccination
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Passive Immunity Naturally Acquired: antibodies passed from mother to fetus through umbilical cord or breast milk Artificially Acquired: antibodies injected into the blood stream
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