BSC2086 A P II Exam 3 Study Guide Lesson 11 The Lymphatic System Lymphatic System and Immunity Pathogens Microscopic organisms that cause disease o Viruses o Bacteria o Fungi o Parasites Immune System o Immunity The ability to resist infection and disease ALL body cells tissues involved in production of immunity NOT just the lymphatic system o Two 2 Main Types of Defenses Nonspecific Defenses Block or attack any potential infectious Cannot distinguish one attack from another Specific Defenses Identify attack and develop immunity to a organism specific pathogen Lymphocytes Lymphatic System protects us against disease o Lymphatic system cells respond to Environmental pathogens Toxins Abnormal body cells i e cancers Structures of Body Defenses Organization of Lymphatic System o Lymph A fluid similar to plasma but without plasma proteins o Lymphatic Vessels Lymphatics Carry lymph from peripheral tissues to the venous system o Lymphoid Tissues Lymphoid Organs o Lymphocytes phagocytes and other immune system cells 1 BSC2086 A P II Exam 3 Study Guide Function of lymphatic system to produce maintain and distribute lymphocytes o Lymphocytes detect problems travel to site of injury or infection Lymphocyte Production o Lymphocytes are produced by lymphoid stem cells In lymphoid tissues i e tonsils In lymphoid organs i e spleen thymus In red bone marrow Lymphocyte Circulation from blood to interstitial fluid through capillaries 2 BSC2086 A P II Exam 3 Study Guide o Returns to venous blood through lymphatic vessels Circulation of Fluids from blood plasma to lymph and back to venous system o Transports hormones nutrients waste products Lymphatic Vessels Vessels that carry lymph o Lymphatic system begins with lymphatic capillaries smallest vessels Differ from blood capillaries in four 4 ways Start as pockets rather than tubes dead ends Larger diameters Thinner walls Flat irregular outline in sectional view Endothelial cells loosely bound together with overlap Overlap acts as one way valve o Allows fluids solutes viruses and bacteria to enter o Prevents return to intercellular space o Edema of tissue causes overlapping endothelial cells to separate allowing fluid into the lymphatic capillaries Lymph Flow from lymphatic capillaries to larger lymphatic vessels containing one way valves o Lymphatic vessels travel with veins o Transports lymph to Right Lymphatic Duct collects lymph from the right side of the body superior to the diaphragm Thoracic Duct left collects lymph from the body inferior to the diaphragm and from the left side of the body superior to the diaphragm Connected to subclavian vein to combine with venous return o Lacteals Special lymphatic capillaries in small intestine Transport lipids absorbed from digestive tract 3 BSC2086 A P II Exam 3 Study Guide Lymphedema Severe swelling caused by blockage of lymph drainage from a limb o o Toxins and pathogens accumulate in swollen area Interferes with immune system function Can overwhelm local defenses without triggering immune system o If persistent connective tissue loses elasticity and swelling becomes permanent Lymphocytes o Make up 20 30 of circulating leukocytes o Most are stored NOT circulating o Types of Lymphocytes T Cells B Cells NK Cells o T Cells Thymus dependent Make up 80 of circulating lymphocytes Main types Cytotoxic T TC Cells Produce cell mediated immunity o Attack cells that have been infected by viruses Memory T Cells Remain in body to remember immunity o Formed in response to exposure to foreign substance Helper T TH Cells Stimulate function of T B cells Suppressor T TS Cells Inhibit function of T B cells 4 BSC2086 A P II Exam 3 Study Guide o B Cells Bone marrow derived Responsible for humoral immunity Make up 10 15 of circulating lymphocytes Differentiate into plasma cells that produce secrete antibodies immunoglobin proteins Antigens Targets that identify any pathogen or foreign compound Immunoglobulins Antibodies Binding of a specific antibody to its specific target antigen initiates antibody mediated immunity chain of events that destroys the target compound or organism o Natural Killer NK Cells Large Granular Lymphocytes Make up 5 10 of circulating lymphocytes Responsible for immunological surveillance Attack foreign cells virus infected cells and cancer cells 5 BSC2086 A P II Exam 3 Study Guide o Lymphocytes wander through tissues Enter blood vessels or lymphatics for transport Can survive many years 80 live up to 4 years some last more than 20 years o Lymphopoiesis lymphocyte production Involves Bone marrow Thymus Peripheral lymphoid tissues lymphoid stem cells Lymphoid Stem Cells Group 1 Hemocytoblasts in bone marrow divide into two 2 types of o Remain in bone marrow develop with help of stromal cells produce the cytokine interleukin 7 to promote B cell differentiation o Produces B cells natural killer cells Group 2 o Migrates to thymus o Produces T cells in environment isolated by blood thymus barrier 6 BSC2086 A P II Exam 3 Study Guide T Cells B Cells Migrate through body to defend peripheral tissues Retain their ability to divide o Produces daughter cells of the same type o This ability is essential to immune system function Lymphoid Tissues Connective tissues dominated by lymphocytes Lymphoid Nodules Areolar tissue with densely packed lymphocytes o Germinal center contains dividing lymphocytes Located in the central zone of the nodule o Distribution Lymph nodes spleen respiratory tract tonsils Along digestive urinary and reproductive tracts 7 BSC2086 A P II Exam 3 Study Guide Mucosa Associated Lymphoid Tissue MALT Lymphoid tissues associated with the digestive system o Protects epithelia of the digestive reproductive urinary and respiratory o Aggregated Lymphoid Nodules Peyer s Patches Clustered deep to organ systems intestinal epithelial lining o Appendix Vermiform Appendix contains a mass of fused lymphoid Lymphoid Organs separated from surrounding tissues by a fibrous connective nodules tissue capsule Include o Lymph nodes Thymus Spleen o Lymph Nodes Afferent lymphatics carry lymph from peripheral tissues to lymph Efferent lymphatics leave lymph node at hilum carry lymph to node venous circulation 8 BSC2086 A P II Exam 3 Study Guide Lymph node functions as a filter B T cells located in the lymph node Purifies lymph before return to venous circulation Removes o Debris o Pathogens o 99 of antigens Antigen Presentation first step in immune response Macrophages extract antigens flowing through lymph node
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