Lymphatic System • Consists of: – Lymph – Lymphatic vessels – Lymphatic tissue – Lymph nodes – Tonsils – Spleen – Thymus. Lymphatic Vessels Return ISF to the vascular system Lymphatic Vessels 4 Types of Lymphatic Vessels • Lymphatic capillaries • Lymphatic collecting vessels • Lymphatic trunks • Lymphatic ducts. Lymphatic Capillaries • What do they do? Lymphatic Capillaries • Blind. • Endothelium. • Loose. • Overlapping. • Permeability. • Flow. Where do we find lymphatic capillaries? • Almost everywhere there are… • Exceptions? Lacteals – Specialized Lymphatic Capillaries in the Small Intestine • Found in the villi. • Function ? • Chyle Lymphatic Collecting Vessels • Receive lymph from… • Similar to what blood vessel? • Locations? • Cleaning? Lymphatic Trunks • Receive lymph from... • Types? Right Lymphatic Duct and Thoracic Duct Lymph Flow Factors Promoting Lymph Flow What If Lymph Cannot Flow? Lymphoid Cells • Reticular cells. – Make… – Support… • Macrophages. – Kill… – Activate… • Dendritic cells. – Kill … – Activate… Lymphoid Cells • T lymphocytes. – Kill …. – Control... • B lymphocytes. – Become… – Secrete... Lymphoid Tissue • Aggregations of... • Functions? • Types: – Diffuse – Lymphoid follicles. Diffuse Lymphatic Tissue • Especially prominent in… • MALT – GALT – BALT • Also in… Lymphoid Follicles/Nodules • Solid, spherical clusters of… • Found throughout the… • Also in the… Lymphoid Follicles/Nodules Peyer’s Patches • Aggregates of… • Found in the… Appendix • Blind outpocketing of the… • Contains aggregates of... • Function Lymphoid Organs • Characterized by dense connective tissue capsule. • Lymph nodes, tonsils, thymus, spleen. Lymph Nodes • Filter... • Receive lymph from… • Send lymph to… Lymph Nodes: 3 Main Superficial Locations Lymph Node • Receives from... • Drains into... • Hilus/Hilum • Dense CT capsule • Trabeculae Afferent >> Efferent Lymph Node Cortex • Subcapsular sinus • Cortical sinuses • Diffuse tissue • Follicles • Reticular fibers • B and T Lymphocytes Antigen Challenge Lymph Node Medulla • Medullary sinuses • Medullary cords • Diffuse tissue • Reticular fibers • T Lymphocytes Antigen Challenge Lymph Node Lymph Flow • A • S • C • M • E Lymph Node Blood Flow Spleen Functions of the Spleen • Destroying defective/aged… • Storing… • Storing… • Destroying… • Antigen challenge Capsule – Trabeculae – Reticular Fibers Spleen Blood Flow Splenic Artery Trabecular Arteries Central Arteries Splenic Arterioles Splenic Cords and Sinuses Pulp Veins Trabecular Veins Splenic Vein red pulp Red Pulp and White Pulp Red Pulp and White Pulp red pulp Thymus • Most active during… • No killing. • Function? Thymus Thymus Blood Flow Blood-Thymus Barrier Aging and the Thymus Aging and the Thymus Tonsils • Ring of lymphatic tissue at the... • 3 main types: – P – P – L Tonsils • CT capsule • Oral epithelium • Crypts • Follicles Palatine Tonsils •Located laterally in the posterior oral cavity. •Largest and most often infected. Pharyngeal Tonsils •Located in the posterior nasopharynx. •A.k.a adenoids. Lingual Tonsils Located at the base of the tongue. Tonsils.