Returns fluids that leaked from blood vessels back to blood Consists of three parts

Transcription

1 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 cleanse lymph 1

2 Lymphoid Organs and Tissues Provide structural basis of immune system House phagocytic cells and lymphocytes Structures include spleen, thymus, tonsils, other lymphoid tissues 2

3 Lymphatic System: Functions Lymphatic vessels (lymphatics) Return interstitial fluid and leaked plasma proteins back to blood ~ 3L / day Once interstitial fluid enters lymphatics, called lymph 3

4 Figure 20.2a The lymphatic system. Internal jugular vein Entrance of right lymphatic duct into vein Entrance of thoracic duct into vein Thoracic duct Cisterna chyli Collecting lymphatic vessels Aorta Regional lymph : Cervical Axillary Inguinal Drained by the right lymphatic duct Drained by the thoracic duct General distribution of collecting lymphatic vessels and regional lymph. MDufilho 9/19/13 4

5 Venous system Arterial system Heart Lymphatic system: Lymph duct Lymph trunk Lymph node Lymphatic collecting vessels, with valves Blood capillaries Lymphatic capillary Tissue fluid Tissue cell Blood capillaries Lymphatic 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, 9/19/13 forming flaplike minivalves. MDufilho 5 Figure 20.1

6 Right jugular trunk Right lymphatic duct Right subclavian trunk Right subclavian vein Right bronchomediastinal trunk Brachiocephalic veins Superior vena cava Azygos vein Cisterna chyli Internal jugular veins Esophagus Trachea Left subclavian trunk Left jugular trunk Left subclavian vein Entrance of thoracic duct into vein Left bronchomediastinal trunk Ribs Thoracic duct Hemiazygos vein 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. 6 Figure 20.2b

7 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 MDufilho 9/19/13 7

8 Lymph Nodes Principal lymphoid organs of the body Embedded in connective tissue, in clusters along lymphatic vessels Near the body surface in inguinal, axillary, and cervical regions of the body 8

9 Figure 20.2a The lymphatic system. Internal jugular vein Entrance of right lymphatic duct into vein Entrance of thoracic duct into vein Thoracic duct Cisterna chyli Collecting lymphatic vessels Aorta Regional lymph : Cervical Axillary Inguinal MDufilho Drained by the right lymphatic duct Drained by the thoracic duct General distribution of collecting lymphatic vessels and regional lymph. 9/19/13 9

10 Afferent lymphatic vessels Cortex Lymphoid follicle Germinal center Subcapsular sinus Efferent lymphatic vessels Hilum Medulla: Medullary cord Medullary sinus Trabeculae Capsule (a) Longitudinal view of the internal structure of a lymph node and associated lymphatics 10 Figure 20.4a

11 Figure 20.5 Lymphoid organs. 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 MDufilho 9/19/13 11