Cardiovascular System LYMPH AND LYMPHATIC VESSELS Venous system Arterial system Large veins Heart (capacitance vessels) Elastic arteries Large (conducting lymphatic vessels) vessels Lymph node Muscular arteries (distributing Lymphatic vessels) system Small veins (capacitance Arteriovenous vessels) anastomosis Lymphatic Sinusoid capillary Arterioles (resistance vessels) Postcapillary Terminal arteriole venule Metarteriole Thoroughfare Capillaries Precapillary sphincter channel (exchange vessels) Copyright © 2010 Pearson Education, Inc. Figure 19.2 Regional Internal jugular vein lymph nodes: Cervical nodes Entrance of right lymphatic duct into vein Entrance of thoracic duct into vein Axillary nodes Thoracic duct Cisterna chyli Aorta Inguinal nodes Lymphatic collecting vessels Drained by the right lymphatic duct Drained by the thoracic duct (a) General distribution of lymphatic collecting vessels and regional lymph nodes. Figure 20.2a Lymphatic System Outflow of fluid slightly exceeds return Consists of three parts 1. A network of lymphatic vessels carrying lymph 1. Transports fluid back to CV system 2. Lymph nodes 1. Filter the fluid within the vessels 3. Lymphoid organs 1. Participate in disease prevention Lymphatic System Functions 1. Returns interstitial fluid and leaked plasma proteins back to the blood 2. Disease surveillance 3. Lipid transport from intestine via lacteals Venous system Arterial system Heart Lymphatic system: Lymph duct Lymph trunk Lymph node Lymphatic collecting vessels, with valves Tissue fluid Blood Lymphatic capillaries Tissue cell capillary Blood Lymphatic capillaries capillaries (a) Structural relationship between a capillary bed of the blood vascular system and lymphatic capillaries. Filaments anchored to connective tissue Endothelial cell Flaplike minivalve Fibroblast in loose connective tissue (b) Lymphatic capillaries are blind-ended tubes in which adjacent endothelial cells overlap each other, forming flaplike minivalves. Figure 20.1 Lymph Interstitial fluid which enters lymph capillaries Lower concentration of proteins than blood Electrolyte differences Hydrostatic and colloid osmotic pressure regulate exchange HP = hydrostatic pressure • Due to fluid pressing against a wall • “Pushes” • Arteriole Venule In capillary (HPc) • Pushes fluid out of capillary Interstitial fluid • 35 mm Hg at arterial end and 17 mm Hg at venous end of capillary in this example Capillary • In interstitial fluid (HPif) Net HP—Net OP Net HP—Net OP • Pushes fluid into capillary (35—0)—(26—1) (17—0)—(26—1) • 0 mm Hg in this example Net Net OP = osmotic pressure • Due to presence of nondiffusible HP OP Net Net 35 25 solutes (e.g., plasma proteins) HP OP • “Sucks” mm mm 17 25 • In capillary (OPc) mm mm • Pulls fluid into capillary • 26 mm Hg in this example • In interstitial fluid (OPif) • Pulls fluid out of capillary NFP (net filtration pressure) NFP is ~8 mm Hg; • 1 mm Hg in this example is 10 mm Hg; fluid moves out fluid moves in Figure 19.17 Venous system Arterial system Large veins Heart (capacitance vessels) Elastic arteries Large (conducting lymphatic vessels) vessels Lymph node Muscular arteries (distributing Lymphatic vessels) system Small veins (capacitance Arteriovenous vessels) anastomosis Lymphatic Sinusoid capillary Arterioles (resistance vessels) Postcapillary Terminal arteriole venule Metarteriole Thoroughfare Capillaries Precapillary sphincter channel (exchange vessels) Figure 19.2 Lymphatic Vessels One-way system, lymph flows toward the heart Lymph vessels (lymphatics) include: Lymphatic capillaries Lymphatic collecting vessels Lymphatic trunks and ducts Lymphatic Capillaries Similar to blood capillaries, except… Not continuous No basement membrane = very permeable Take up cell debris, pathogens, and cancer cells Endothelial cells overlap to form one-way mini-valves Filaments anchored to connective tissue Endothelial cell Flaplike minivalve Fibroblast in loose connective tissue (b) Lymphatic capillaries are blind-ended tubes in which adjacent endothelial cells overlap each other, forming flaplike minivalves. Figure 20.1b Lymphatics Collecting vessels Capillaries join to form larger vessels = lymphatics Empty into thoracic duct or right lymphatic duct Similar to veins, except Have thinner walls, with more internal valves Anastomose more frequently More valves Occasionally modified to form nodes Lymphatic Ducts Lymph is delivered into one of two large ducts Right lymphatic duct Drains the right upper arm and the right side of the head and thorax Thoracic duct Arises from the cisterna chyli and drains the rest of the body Connect with subclavian veins Right jugular trunk Internal jugular veins Right lymphatic duct Esophagus Right subclavian trunk Trachea Right subclavian vein Left subclavian trunk Right broncho- Left jugular trunk mediastinal trunk Left subclavian vein Brachiocephalic veins Entrance of thoracic Superior vena cava duct into vein Left bronchomediastinal Azygos vein trunk Ribs Thoracic duct Hemiazygos vein Cisterna chyli Right lumbar trunk Left lumbar trunk Inferior vena cava Intestinal trunk (b) Major lymphatic trunks and ducts in relation to veins and surrounding structures. Anterior view of thoracic and abdominal wall. Figure 20.2b Lymphatics Regional Internal jugular vein lymph nodes: Cervical nodes Entrance of right lymphatic duct into vein Entrance of thoracic duct into vein Axillary nodes Thoracic duct Cisterna chyli Aorta Inguinal nodes Lymphatic collecting vessels Drained by the right lymphatic duct Drained by the thoracic duct (a) General distribution of lymphatic collecting vessels and regional lymph nodes. Figure 20.2a Lymph Transport No pump Lymph movement similar to venous return Valves Skeletal muscle contraction Thoracic pump Pressure gradients Also contraction of nearby arteries and smooth muscle within vessels Movement is slow and sporadic Edema Lymphedema Prevention of return of lymph to blood May be due to: Osmotic changes Blockage of lymph vessels Parasites Inflammation Surgery Elephantiasis Lymphatic Tissues Tissues house and provide a proliferation site for lymphocytes Furnish a surveillance vantage point Mucosa-associated lymphatic (MALT) Respiratory, digestive, urinary, reproductive systems Peyer’s patches Junction of large and small intestine Lymphoid nodules (follicles) of Peyer’s patch Smooth muscle in the intestinal wall Figure 20.9 Lymph Nodes Solid, spherical, well-defined organs Distributed along course of lymphatic vessels Concentrated Cervical region Behind the ear, inferior mandible and lateral neck Axillary region Abdomen Along abdominal aorta and mesenteric arteries Inguinal region Lymph Nodes Functions 1. Filter lymph Macrophages destroy microorganisms and debris 2. Immune system Lymphocytes are activated and mount an attack against antigens Lymph Nodes Structure Outer parenchyma Inner medulla Medullary sinuses Macrophages Cortex contains follicles with germinal centers, heavy with dividing B cells Macrophage Reticular cells on reticular fibers Lymphocytes Medullary sinus Reticular fiber Copyright © 2010 Pearson Education, Inc. Figure 20.3 Regional Internal jugular vein lymph nodes: Cervical nodes Entrance of right lymphatic duct into vein Entrance of thoracic duct into vein Axillary nodes Thoracic duct Abdominal Cisterna chyli Aorta Inguinal nodes Lymphatic collecting vessels Drained by the right lymphatic duct Drained by the thoracic duct (a) General distribution of lymphatic collecting vessels and regional lymph nodes. Figure 20.2a Afferent Cortex lymphatic • Lymphoid follicle vessels • Germinal center • Subcapsular sinus Efferent lymphatic Follicles vessels Trabecula Subcapsular sinus Hilum Capsule Medulla: • Medullary cord • Medullary sinus Medullary cords Trabeculae Medullary sinuses Capsule (b) Photomicrograph of part of a (a) Longitudinal view of the internal structure lymph node (72x) of a lymph node and associated lymphatics Figure 20.4 Spleen Largest lymphoid organ Macrophages remove old RBC’s, platelets and bacteria Production of RBC’s In fetus and severely anemic patients Splenic contraction May return 200-300 mls of blood to circulation from sinuses Regional Internal jugular vein lymph nodes: Cervical nodes Entrance of right lymphatic duct into vein Entrance of thoracic duct into vein Axillary nodes Thoracic duct Spleen Cisterna chyli Aorta Inguinal nodes Lymphatic collecting vessels Drained by the right lymphatic duct Drained by the thoracic duct (a) General distribution of lymphatic collecting vessels and regional lymph nodes. Figure 20.2a Capsule Trabecula Splenic cords Venous sinuses Arterioles and Splenic capillaries artery Splenic Red pulp vein Hilum White pulp Central artery (a) Diagram of the spleen, anterior view Splenic artery Splenic vein (b) Diagram of spleen histology Figure 20.6a,b Big spleen! Thymus Involution Stops growing during adolescence and then gradually atrophies Replaced by adipose and connective tissue Thymus Thymic (Hassall’s) corpuscle Medulla Cortex Figure 20.7 Thymus Hormones Thymopoetin and thymosin Assist in lymphocyte differentiation Tonsils Simplest lymphoid organs 3 pairs Palatine tonsils Posterior end oral cavity “Sore throat” Lingual tonsils Grouped at the base of the tongue Pharyngeal tonsils Adenoids Posterior wall of the nasopharynx Pharyngeal tonsil Palatine tonsil Lingual tonsil Tonsil Tonsillar crypt Germinal centers in lymphoid follicles Figure 20.8 Tonsillitis Questions? Remember HW due on Tuesday and in Lab! Quiz Study Guide is in the “Exams” Section .