Dr. Patron Chapter 16 Lymphatic Sys and Immunity 2024 PDF

Because learning changes everything. ® Chapter 16 Lymphatic System and Immunity Hole’s Human Anatomy & Physiology 2024 Release Charles J. Welsh, Cynthia Prentice Craver © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written conse...

Because learning changes everything. ® Chapter 16 Lymphatic System and Immunity Hole’s Human Anatomy & Physiology 2024 Release Charles J. Welsh, Cynthia Prentice Craver © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.  16.1 Overview of the Lymphatic System Lymphatic system: A collection of cells and biochemicals that travel in lymphatic vessels Contains a network of vessels that assist in circulating fluids Closely associated with the cardiovascular system 3 functions of the lymphatic system: Transports excess interstitial fluid away from the interstitial spaces, and returns it to the bloodstream Absorbs lipids from digestive system, and transports them to the bloodstream; accomplished by lymphatic capillaries called lacteals Defends the body against diseases, and allows humans to live in world with other organisms The term “immune system” refers to the fact that many cells of the lymphatic system provide both defense against disease and permanent immunity against future infections © McGraw Hill, LLC 2  Figure 16.1 Lymphatic Vessels Transport Fluid from the Interstitial Spaces to the Bloodstream Access the text alternative for slide images. © McGraw Hill, LLC 3  16.2 Lymphatic Pathways Lymphatic pathways: Lymphatic capillaries → lymphatic vessels → lymph nodes → larger lymphatic vessels → lymphatic trunks → lymphatic collecting ducts → subclavian veins in thorax Lymphatic capillaries: Microscopic, closed-ended tubes Networks parallel blood capillaries throughout the body Thin-walled Walls formed from simple squamous epithelium Tissue (interstitial) fluid enters lymphatic capillaries; fluid is now called lymph Merge into lymphatic vessels © McGraw Hill, LLC 4  Figure 16.2 Lymphatic Capillaries Access the text alternative for slide images. © McGraw Hill, LLC 5  Lymphatic Vessels Walls are similar to veins, but thinner Lymphatic vessels are composed of 3 layers: Inner layer: An endothelial lining Middle layer: Smooth muscle and elastic fibers Outer layer: Connective tissue *Contain semilunar valves, which allow one-way flow Larger vessels lead to lymph nodes and then to larger lymphatic trunks © McGraw Hill, LLC 6  Figure 16.3 Valve in a Lymphatic Vessel Dennis Strete/McGraw Hill © McGraw Hill, LLC 7  Lymphatic Trunks and Collecting Ducts Lymphatic trunks: Drain lymph from lymphatic vessels Named for the regions they serve: Lumbar, intestinal, intercostal, bronchomediastinal, subclavian, and jugular Drain into lymphatic collecting ducts Lymphatic collecting ducts: Drain lymph from trunks Two for the entire lymphatic system: Thoracic duct: Longer and wider of the two ducts Drains majority of body Begins as sac called cisterna chyli, empties into L. Subclavian Vein Right lymphatic duct: Much smaller than thoracic duct Begins in left thorax, empties into R. Subclavian Vein Drains upper left portion of body © McGraw Hill, LLC 8  Figure 16.5 Lymphatic Trunks and Collecting Ducts Access the text alternative for slide images. © McGraw Hill, LLC 9  Figure 16.6 Lymphatic Pathways and Drainage Access the text alternative for slide images. © McGraw Hill, LLC 10  Figure 16.7 Summary of the Lymphatic Pathway Access the text alternative for slide images. © McGraw Hill, LLC 11  16.3 Tissue Fluid and Lymph Lymph is tissue fluid that has entered a lymphatic capillary. Lymph formation depends on tissue fluid formation. Tissue Fluid formation: Capillary blood pressure filters water and small molecules from the plasma The resulting tissue fluid: Has about the same composition as blood plasma Contains water and dissolved nutrients, gases, hormones Exception: tissue fluid does not contain large plasma proteins, which remain in blood plasma, to maintain osmotic pressure necessary to draw fluid back into blood capillaries *Tissue fluid = blood plasma − plasma proteins © McGraw Hill, LLC 12  Lymph Formation Filtration from the plasma normally exceeds reabsorption, leading to the net formation of tissue fluid This increases the tissue fluid hydrostatic pressure within interstitial spaces, forcing fluid into lymphatic capillaries, and forming lymph This process prevents accumulation of excess tissue fluid or edema Example of edema: When a woman has axillary lymph nodes removed during breast cancer surgery, lymphatic drainage is obstructed from upper limb, resulting in edema © McGraw Hill, LLC 13  Lymph Flow Lymph inside lymphatic vessels has low hydrostatic pressure, like venous blood Good lymphatic flow requires help from several mechanisms Muscle activity influences the movement of lymph through the lymphatic vessels: Contraction of skeletal muscles compresses lymphatic vessels, moving the lymph Respiratory process creates low pressure in thorax, and high pressure in abdomen during inspiration; sends lymph from abdomen to thorax Smooth muscle in the larger lymphatic vessels contracts to aid in flow of lymph Valves in lymphatic vessels prevent backflow Lymphatic flow is highest during physical exercise © McGraw Hill, LLC 14  Lymph Function Roles of lymphatic capillaries: Absorption of dietary fats in small intestine, and delivery to the bloodstream Return of small proteins filtered by blood capillaries to bloodstream Collection of excess interstitial fluid Delivery of excess fluid to the bloodstream Delivery of foreign particles to the lymph nodes Flap-like valves between cells of lymphatic capillaries allow easy entry of tissue fluid © McGraw Hill, LLC 15  Figure 16.8 Tissue Fluid Becoming Lymph Access the text alternative for slide images. © McGraw Hill, LLC 16  16.4 Lymphatic Tissues and Lymphatic Organs Lymphatic tissue contains several cell types, including lymphocytes and macrophages Mucosa-associated lymphoid tissue (MALT): Unencapsulated lymphatic tissue of the digestive, respiratory, urinary, and reproductive tracts Tonsils and appendix are composed of lymphatic nodules (compact masses of lymphatic tissue) Peyer’s patches are aggregates of lymphatic nodules found in ileum (distal part of small intestine) Lymphatic organs: Consist of encapsulated lymphatic tissue Lymph nodes, thymus, and spleen © McGraw Hill, LLC 17  Lymph Nodes Lymph nodes are usually bean-shaped,