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The Lymphatic System. Non-Specific Defenses Physical Barriers Epithelium, hair, secretions, acid, enzymes Phagocytes 1 st line of cellular defense – removes.

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Presentation on theme: "The Lymphatic System. Non-Specific Defenses Physical Barriers Epithelium, hair, secretions, acid, enzymes Phagocytes 1 st line of cellular defense – removes."— Presentation transcript:

1 The Lymphatic System

2 Non-Specific Defenses Physical Barriers Epithelium, hair, secretions, acid, enzymes Phagocytes 1 st line of cellular defense – removes debris and pathogens Microphages leave blood stream and enter peripheral tissues (neutrophils and eosinophils) Macrophages – sensitive to chems in surrounding fluids can be free or fixed Interferons Slow spread of viral infections Stimulate macrophages and NK cells Inflammation Initiated by mast cells releasing histamines and heparin Local swelling, heat, redness, and pain Slows spread of pathogens Necrosis – tissue destruction via lysosomes Pus – accumulation of dead cells and debris (abscess – accumulation of pus) Fever (>98 o F) Pyrogens – proteins reset body's “thermostat” Incr. rate of metabolism Over 104 o F damages CNS, nausea, hallucination, and convulsions

3 Organization Lymph Vessels Begin at peripheral tissue  venous system Small valves prevent backflow Lymph Fluid Blood plasma but w/less proteins Lymphocytes Cells defend body 80% last 4 years…some last 20 years or more! Lymph Tissue Loose connective tissue Tonsils, Appendix, Peyer’s Patches Size can increase or decrease depending on number of lymphocytes Lymph Organs Lymph nodes Spleen Thymus

4 Lymph Vessels Lead towards trunk of body and empty into 2 ducts Thoracic duct – lower abdomen, pelvis, lower limbs, left head, neck, and chest Right lymphatic duct – right side of body, above diaphragm Lymphodema (edema) – blockage of lymph drain

5 Functions Protect body from pathogens Production, maintenance, and distribution of lymphocytes Return fluid from peripheral tissues to blood Distribute hormones, nutrients, and waste to general circulation

6 Lymphoid Organs Lymph Nodes Filter and purify lymph before enters venous system Detects and removes antigens Stimulates T cells and B cells initiating immune response Lymphomas – cancer arising from lymphocytes Thymus Decrease in size after puberty T cell production and maturation Spleen 5” long on left side, deep red Filters blood, removes abnormal blood cells and initiates B cell and T cell responses to antigens Macrophages identify and engulf damaged or infected cells

7 Lymphocytes 25% of circulating wbc T cells – thymus dependent (80% circulating lymphocytes) Cytotoxic T cells – attack foreign cells or body cells infected w/ virus Helper T cells – stimulate T cells and B cells Suppressor T cells – inhibit T cells and B cells B cells -bone marrow derived (10-15% circ. Lymphocytes) Plasma cells – secrete antibodies (immunoglobulins) Antibodies bind to antigens NK cells natural killer cells (5-10% circulating lymphocytes) Attack foreign cells, viral infected cells, and cancer cells

8 Specific Defenses Immunity – respond to the presence of specific antigens Antigens – “non-self” substance that excites the immune system and stimulates a response Genes determine specificity T cells – cell mediated immunity Defend against abnormal cells Pathogens inside of cells B cells – antibody-mediated immunity Defend against antigens and pathogens in body fluids Antibodies (immunoglobulins) – bind to specific antigen, Y shape with 2 antigen binding sites

9 Immune Response (antibody mediated) B cell binds w/antigen…becomes activated and produces clones B cell clones Plasma cells – secrete antibodies (2,000 per sec!)… reaches peak 10 days Memory B cells – continue to circulate, and can speed process to 2-3 days if recognizes an “old enemy”

10 Immune Response (cell mediated) T cells cannot bind to “free” antigen Macrophages and B cells must present antigen to T cells Once T cell binds to “presented” antigen Killer (cytotoxic) T cells Binds to target cell and inserts a toxic chem… target cell ruptures Helper T cells Recruit other cells to fight invaders Stimulates B cells to increase production of antibodies Simulates Killer T cells to multiply Suppressor T cells Release chems to suppress B and T cell activity Most T cells enlisted to fight die w/in a few days Some remain as memory cells to respond quickly to subsequent invasions

11 Properties of Immunity Specificity T cells and B cells target one specific antigen Versatility Millions different lymphocytes w/diff antigen receptors Memory 1 st exposure – lymphocytes divide to create “attack” cells and memory cells Response to 2 o exposure to antigen is stronger than 1 st Tolerance Doesn’t respond to normal “self” tissues or antigens

12 Types of Immunity Innate – genetically determined Acquired – arises during life Active – appears after exposure to antigen Naturally- continually induced as encounter “new” pathogens or antigens Induced – stimulated under controlled conditions Vaccine: dead/inactive pathogen that induces an immune response Passive – transfer of antibodies from another source Naturally – mother to baby Gestation – via placenta Infancy – via breast milk Induced – antibodies administered to fight infection or prevent disease after exposure

13 Lymphatic Project Cartoon/comic strip analogous to lymphatic system that highlights functions of B cells, plasma cells, antibodies, and memory B cells, Helper Tcells, Killer T cells, and suppressor T cells Research and write an essay on allergies, organ transplant and rejection, multiple sclerosis, systemic lupus, OR HIV/AIDS


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