Module 7 - Lymphatic System PDF

Module 7 The Lymphatic System Mr Bashir Sumar School of Nursing and Midwifery  Important Copyright Notice for Western Sydney University Students The material in this presentation has been made available to you by and on behalf of Western Sydney Universit...

Module 7 The Lymphatic System Mr Bashir Sumar School of Nursing and Midwifery  Important Copyright Notice for Western Sydney University Students The material in this presentation has been made available to you by and on behalf of Western Sydney University for your personal use and study only. The material contained in this presentation is subject to copyright protection. You may not make any further copies and share the recorded lectures in whole or in part by any hardcopy, digital and or online technologies. Learning outcomes Students should be able to: 1. List the functions of the lymphatic system and its components 2. Describe the structure and distribution of the lymphatic vessels, tissues and organs 3. Identify the source of lymph and describe mechanisms of lymph transport and transport pathways 4. Associate the cells of the specific immune response to the lymphatic system 5. Discuss the role and importance of lymph nodes for the specific immune response.  Figure 20.1a Distribution and special features of lymphatic capillaries. Venous system Arterial system Heart Lymphatic system: Lymph duct Lymph trunk Lymph node Collecting lymphatic vessels, with valves Tissue fluid Blood Lymphatic capillaries capillary Tissue cell Blood Lymphatic capillaries capillaries Structural relationship between a capillary bed of the blood vascular system and lymphatic capillaries.  Figure 20.1b Distribution and special features of lymphatic capillaries. Filaments anchored to connective tissue Endothelial cell Flaplike minivalve Fibroblast in loose connective tissue Lymphatic capillaries are blind-ended tubes in which adjacent endothelial cells overlap each other, forming flaplike minivalves.  Lymphatic System Returns fluids that leaked from blood vessels back to blood Consists of three parts 1. Network of lymphatic vessels (lymphatics) 2.Lymph – fluid in vessels 3.Lymph nodes – cleanse lymph The Lymphatic System consists of Lymphatic Vessels – which return excess interstitial fluid back to the blood Lymph nodes – present along the lymph channels where lymph is filtered and cleansed of foreign particles and microorganisms Larger secondary lymph organs and tissues - such as the spleen, tonsils, Payer's patches and other Mucosa Associated Lymph Tissue (MALT) Lymph – similar to blood plasma, containing White cells called lymphocytes which mount an immune response to antigens and phagocytes which engulf antigens. 7 Functions of the Lymphatic System to control tissue fluid composition to produce the immune response to specific antigens to provide a long term defence against pathogens to absorb digested fat in the intestine through lacteals which are specialised lymph capillaries present in the mucosa 8 Figure 20.3 The lymphatic system. Regional lymph nodes: Entrance of Cervical right lymphatic nodes duct into vein Entrance of thoracic duct into vein Axillary nodes Thoracic duct Inguinal Collecting nodes lymphatic vessels Drained by the right lymphatic duct Drained by the thoracic duct General distribution of collecting lymphatic vessels and regional lymph nodes. Lymph Transport Lymph propelled by – Milking action of skeletal muscle – Pressure changes in thorax during breathing – Valves to prevent backflow – Pulsations of nearby arteries – Contractions of smooth muscle in walls of lymphatics Lymphoid Cells Lymphocytes main warriors of immune system – Arise in red bone marrow Mature into one of two main varieties – T cells (T lymphocytes) – B cells (B lymphocytes) Lymphocytes….cont’d T cells and B cells protect against antigens – Anything body perceives as foreign Bacteria and bacterial toxins, viruses, mismatched RBCs, cancer cells T cells – Manage immune response and AB prod’n – Attack and destroy infected cells B cells – Produce plasma cells, which secrete antibodies Antibodies mark antigens for destruction by phagocytosis or other means Lymphoid Tissue Houses, and provides proliferation site for, lymphocytes Surveillance vantage point for lymphocytes and macrophages Examples are – those lining the mucous membranes of the GIT (MALT) – Those that occur in the intestinal walls (Peyer’s patches) Lymph Nodes Principal lymphoid organs of body Embedded in connective tissue, in clusters along lymphatic vessels Near body surface in inguinal, axillary, and cervical regions of body Functions 1. Filter lymph—macrophages destroy microorganisms and debris 2. Immune system activation—lymphocytes activated and mount attack against antigens Structure of a Lymph Node Vary in shape and size but most bean shaped External fibrous capsule Trabeculae extend inward and divide node into compartments Two histologically distinct regions – Cortex – Medulla Structure of a Lymph Node Cortex contains follicles with germinal centers, heavy with dividing B cells Dendritic cells nearly encapsulate follicles Deep cortex houses T cells in transit T cells circulate continuously among blood, lymph nodes, and lymph Figure 20.6 Lymph node. Afferent lymphatic Cortex vessels Germinal center Efferent lymphatic vessels Hilum Medulla Medullary cord Trabeculae Capsule Longitudinal view of the internal structure of a lymph node and associated lymphatics  Tonsils (in pharyngeal region) Thymus (in thorax; most active during youth) Spleen (curves around left side of stomach) Peyer’s patches (aggregated lymphoid nodules in small intestine) Appendix Figure 20.5 Lymphoid organs.  The Lymphatic System http://www.youtube.com/watch?v=BX8fBl me9vQ