8_Lymphatic System.pptx

Lymphatic System Chapter 19, Human Anatomy (LibreTexts) "Anatomy of the Lymphatic System" by OpenStax is licensed under CC BY 3.0 Functions of the Lymphatic System 1. Fluid balance: it maintains fluid balance between the blood and tissues. Transport excess interstitial fluid, called lymph, back i...

Lymphatic System Chapter 19, Human Anatomy (LibreTexts) "Anatomy of the Lymphatic System" by OpenStax is licensed under CC BY 3.0 Functions of the Lymphatic System 1. Fluid balance: it maintains fluid balance between the blood and tissues. Transport excess interstitial fluid, called lymph, back into circulatory system. Lymph is a fluid connective tissue composed of plasma with leukocytes. 2. Protection: It forms part of the body’s immune system and helps defend against bacteria and other intruders. 3. Fats absorption: It facilitates absorption of fats and fat-soluble nutrients in the digestive system. Structures of the Lymphatic System • Lymph vessels: Lymphatic capillaries, vessels, trunks, and ducts containing lymph • Lymphatic tissues: Tonsils, Mucosa-Associated Lymphoid Tissue (MALT) • Lymphatic organs: Lymph Nodes, Thymus, Spleen "Anatomy of the Lymphatic System" by OpenStax is licensed under CC BY 3.0 Lymph Vessels • Arterial end of capillary bed forces fluid into interstitial space around cells • Venous end of capillary bed reabsorbs most but not all fluid • Lymph vessels absorb excess fluid around capillary beds (about 3L/day) • Lymph vessels are subdivided, from smallest to largest, into: • • • • Lymphatic Lymphatic Lymphatic Lymphatic capillaries vessels trunks ducts Lymphatic Capillaries and Vessels • Lymphatic capillaries are interspersed through capillary beds • Larger diameter than blood capillaries and closed-ended • Formed by endothelial cells like blood capillaries • Lymphatic capillaries merge into lymphatic vessels • Vessels have valves (like veins): prevent pooling of lymph • Some lymphatic vessels connect directly to lymphatic organs called lymph nodes. Lymphatic Capillaries "Lymphatic Capillaries" by OpenStax is licensed under CC BY 3.0 Lymphatic Trunks • Formed from merging lymphatic vessels • Lymphatic trunks drain lymph from major body regions: jugular and subclavian trunks from upper body, lumbar and intestinal trunks from lower body • Cisterna chyli receives lymph from left and right intestinal and lumbar trunks. This lymph is full of fats coming from the small intestine during digestion of fatty foods Lymphatic Ducts • Lymphatic trunks drain into lymphatic ducts • Two major lymphatic ducts: • Right lymphatic duct receives lymph from right side of head and neck, right arm, and right thorax • Thoracic duct that receives lymph from left side of head and neck, left arm, left thorax, everything inferior to diaphragm • Both ducts drain into junction of the subclavian and jugular veins but on opposite sides of the body Overview of Lymphatic Vessels “Lymphatic Vessels, Trunks, and Ducts" by Julie Jenks is a derivative of the original work by Daniel Donnelly and is licensed under CC BY 4.0 Lymphatic Tissues • Also called lymphatic nodules • Different from lymph nodes which have capsule around them • Clusters of lymphatic cells with some extracellular connective tissue, so overall these are made by only one tissue (connective) • Sometimes many nodules together form larger structures: • Mucosa-associated lymphatic tissue (MALT) • Tonsils Mucosa-Associated Lymphatic Tissue (MALT) • Also called Peyer patches • Located in mucosa of gastrointestinal tract (very prominent in small intestine), respiratory, genital, urinary tracts • Detect antigens and start immune response "Mucosa Associated Lymphoid Tissue (MALT) Nodule" by OpenStax is licensed under CC BY 3.0 / Micrograph provided by the Regents of the University of Michigan Medical School © 2012 Tonsils • Protect pharynx from infection • Three groups: • Pharyngeal tonsils (AKA adenoids) in posterior wall of nasopharynx • Palatine tonsils in posterolateral region of oral cavity • Lingual tonsils along posterior 1/3 of tongue • Chronic tonsillitis due to streptococcus or sleep apnea may require tonsillectomy "Location and Histology of Tonsils" by OpenStax is licensed under CC BY 3.0 / Micrograph provided by the Regents of the University of Michigan Medical School © 2012 Lymphatic Organs - Thymus • Large in infants and young, almost nonfunctional in adults • Site where T-lymphocytes (a type of leukocytes) mature • Two thymic lobes surrounded by connective tissue • Trabeculae are fibrous extensions of capsule • Trabeculae divide thymus into lobules; each lobule has • outer cortex; immature T-cells • inner medulla; mature T-cells Thymus Image "The Location Structure and Histology of the Thymus" by OpenStax is licensed under CC BY 3.0 / Micrograph provided by the Regents of the University of Michigan Medical School © 2012 Lymphatic Organs – Lymph Nodes • Monitor lymph for pathogens • Small, round or oval structures located on lymph vessels that house T- and B-lymphocytes in lymphatic nodules • Internal projections of capsule called trabeculae which are pathway for blood vessels and nerves • Outer cortex contains lymphatic nodules • Inner medulla supported by medullary cords • Afferent lymphatic vessels bring lymph to lymph node for filtering • Efferent lymphatic vessels take filtered lymph from lymph nodes • Lymph may pass through several lymph nodes in a cluster Lymph Node Image "Lymph Node" by Julie Jenks is licensed under CC BY 4.0 / a derivative from the original work in (a) and the original work in (b) Lymphatic Organs - Spleen • Monitors blood for pathogens • Largest lymphatic organ • Located on the left side lateral to stomach and pancreas, and anterior to diaphragm • No cortex or medulla • Trabeculae that divide the spleen into nodules consisting of an arteriole surrounded by white pulp and feeding sinusoid capillaries surrounded by red pulp that drain to a venule. Spleen - Image "Spleen" by Julie Jenks is licensed under CC BY 4.0 / A derivative from the original work / Micrograph provided by the Regents of the University of Michigan Medical School © 2012