Lymphatic System Structure and Function 2024 PDF

Lymphatic System Structure and Function Objectives  Learn the overall function of the lymphatic system  Understand the formation, circulation and cleaning of lymph  Identify the organs/tissues/cells of the lymphatic system  Primary Funct...

Lymphatic System Structure and Function Objectives  Learn the overall function of the lymphatic system  Understand the formation, circulation and cleaning of lymph  Identify the organs/tissues/cells of the lymphatic system  Primary Functions of the Lymphatic System Three primary functions 1. Fluid balance:  Excess interstitial fluid enters lymphatic capillaries and becomes lymph (30L from capillaries into interstitial fluid, 27L return leaving 3L that will become lymph). 2. Lipid absorption:  Absorption of fat and other substances from digestive tract by lacteals. Lymph fluid is called chyle. 3. Defense/Immunity:  Microorganisms and other foreign substances are filtered from lymph by lymph nodes and from blood by spleen. This presentation series will explore how the lymphatic system forms lymph. How the lymph is cleaned and then returned to the cardiovascular system to assist in fluid balance. It will not cover defense and immunity, this topic will be addressed in lecture  Overview of Lymphatic System ORGANIZAT ION LYMPH LYMPHA LYMPHA LYMPHA LYMPHA (CHYLE) TIC TICCELL TIC TIC NODULE S VESSELS ORGANS S Fluid Filters Cleans Transpor Filter & lymph lymph & ts lymph clean immunit lymph y Module 1 Module 2 Module 3 Module 4  Overview of lymphatic system process In the next series of modules you will explore the creation of lymph fluid, filtration and cleaning and how it flows through the body. Here is a simple breakdown of the process Interstitial fluid lymphatic capillary becomes lymph lymph node/WBC lymphatic vessels cardiovascular system liver, spleen, bone marrow, thymus Proceed to Module 1 In A&P drawings blood vessels are in red or blue and lymphatic vessels in green  Formation and Filtration of Lymph Objectives Upon completion of this module you will have an understanding of: 1. Capillary Exchange 2. Structure of Lymphatic capillary Capillary Bed Lymphatic Lymph Node Capillary 3. How lymph is produced 4. Structure of lymph node 5. Function of lymph node  Review of Capillary Exchange & Vocabulary Assignment A review of the process of fluid exchange is necessary to understand the process of lymph formation. Vocabulary: look up the following terms and write out the definitions. 1. Diffusion 2. Osmosis 3. Hydrostatic Pressure 4. Oncotic (colloidal osmotic pressure) 5. Osmotic pressure 6. Colloid 7. Interstitial Fluid Capillary exchange Watch the video. Key Points The fluid that is pushed out of the capillary is plasma. The plasma then becomes part of interstitial fluid. More plasma is pushed out then reabsorbed at venous end. This causes an increase in the interstitial fluid. If not removed the tissue will swell causing edema. It is the lymphatic capillaries function to reabsorb the extra interstitial fluid. Lymphatic capillary structure within a capillary bed Lymphatic capillaries (green) is intertwined within the vessels of the capillary bed. – Lymphatic capillaries and the other vessels are referred to as lymphatics – Lymphatics are not an Closed ended tubes enclosed continuous circuit. Lymphatic Capillary Structure Start as pockets rather than tubes Have larger diameters than capillaries Endothelial cells loosely bound together with overlap Overlap acts as one-way valve – Allows fluids, solutes, viruses, and bacteria to enter – Prevents return to intercellular space  Lymphatic Capillary Structure and Function Lymph—Fluid inside the lymphatic Lymph capillary Opening—An opening between two Opening endothelial cells that is pushed open by interstitial fluid. Works like a Endothelium swinging door that opens one direction. Allows fluid to enter the Interstitial fluid lymphatic capillary and not leak back flowing into out. Endothelium—simple squamous cell lymphatic capillary of lymphatic capillary wall Interstitial fluid—fluid around the Tissue cell cells. Excess pushes on lymphatic Interstitial endothelial cell pushing fluid into the fluid lymphatic capillary Creation of Lymph Watch the video review Key points Excess interstitial fluid is taken up by the lymphatic capillary. Once the fluid is in the lymphatic capillary it is lymph. How much fluid cannot be reabsorbed at the venous end and taken up by the lymphatic capillary?  Summary and review of Lymph Formation Fluid circulation, balance and homeostasis in the body requires both the cardiovascular system and the lymphatic system Plasma leaves the cardiovascular system capillaries and becomes interstitial fluid. Interstitial fluid builds up around the cells and then enters lymphatic capillary becomes LYMPH. Lymph than flows through lymphatic vessels and is cleaned by lymph nodes and lymphatic organs. It is then returned to the cardiovascular system. IfPlasma you haveInterstitial Lymph mastered this material Plasma proceed to the graded CANVAS quizFluid    Proceed to the next module on the lymph node  Lymph Nodes This module will cover the lymph node Objectives: – Distribution of the lymph nodes in the body – Structure of the lymph node – How the lymph node functions Distribution of Major Lymph nodes  Lymphoid Tissues and Organs Appendix Lymph Nodes Inguinal lymph nodes Generalized Pathway of lymph flow Lymph produced in the capillary beds is moved to the lymph nodes Lymph Nodes – Afferent lymphatics Carry lymph – From peripheral tissues capillary beds to lymph node – Efferent lymphatics Leave lymph node at hilum Carry lymph to venous circulation Lymph flow into and out of node Makes lymph One way valve Lymph fluid flows into flows in one the lymph node Afferent Afferent Lymphatic direction through afferent LymphaticsVessel vessels Lymph fluid leaves the lymph node through efferent vessels Efferent Lymphatic Vessel Afferent Lymphatic vessel  Lymph fluid filtration and cleaning 6. Abundant T-Cells are located here 2.Area under capsule 1.Forms that allows lymph fluid outer to flow around and into margin of the node. It contains node few lymphocytes 5. Site of B-cell activation and proliferation 4. Lymph fluid is directed from the sinus into the 3. Lymph fluid medulla. It contains travels from the numerous macrophages subcapsular sinus to eat pathogens and into the trabeculae cellular waste and into the center of the node  Diagram Quiz Identify the structures of the lymph node Label the lymph node. Print the slide out or edit with the draw function. 1. Afferent vessels 2. Efferent vessel 3. Subcapsular sinus 4. Follicle 5. Germinal center of follicle 6. Medulla 7. Paracortex  Self Quiz Answer the following questions. Try to answer before clicking to see the correct response. 1. Where are most of the T-cells found inside a lymph node? In the paracortex 2. Which vessels bring lymph into the lymph node? Afferent lymphatics 3. Which vessels take lymph out of the lymph node? Efferent lymphatic 4. Where are B-cells located in the lymph node? Germinal centers of the follicles 5. List two functions of a lymph node. Filter and clean lymph, activate immunity, Production of T &B lymphocytes T & B lymphocytes are first produced in the red bone The T lymphocytes migrate to the thymus to become T-cells. The B lymphocytes mature to B cells in the bone marrow. The T & B cells are then transferred to lymph nodes and other lymphoid organs. T Cells, B Cells and Macrophages Types of WBC T-cells will destroy infected cells and provide immunity B-cells will produce antibodies to fight infections and provide immunity Macrophages will phagocytize debris, bacteria, viruses, and antigens The functions of the WBC will be covered more in the next module. Immune system function Lymph fluid filtration and cleaning Lymph Node Function – A filter As the lymph flows through the node it is cleaned. The macrophages will phagocytize the and remove: – Debris – Pathogens – 99% of antigens – The lymph will be filtered through many lymph nodes on its way A collection of lymph nodes back to the cardiovascular system  Body Defenses (Immunity) Lymphatic System is important in the development of immunity – Lymphoid tissues and lymph nodes are positioned to Monitor peripheral infections Respond before infections reach vital organs of trunk – Lymph nodes of gut, trachea, lungs, and thoracic duct Protect against pathogens in digestive and respiratory systems – Filtration of lymph through the node functions to: Introduce foreign antigens to T&B Cells to activate immunity. Known as antigen presentation. This is the first step in the development of immunity.  Overview There are over 500 lymph nodes in the human body. They function to filter and clean lymph before it is returned to the cardiovascular system. They are packed with T & B cells to activate the first step in development of immunity (antigen presentation) Removal of lymph nodes can lower immunity and impair fluid removal from that area of the body causing edema End Module Two Proceed to Module Three White Blood Cells