Lymphatic Tissue - Tagged.pdf

Lymphatic Tissue Anatomy ATE 1110 Objectives • To become familiar with the anatomy of the lymph system • To understand the function of the lymphatic system • To be able to describe how lymph is removed and transported • To describe the characteristics of lymph • To be able to describe the role of...

Lymphatic Tissue Anatomy ATE 1110 Objectives • To become familiar with the anatomy of the lymph system • To understand the function of the lymphatic system • To be able to describe how lymph is removed and transported • To describe the characteristics of lymph • To be able to describe the role of the different areas of the lymphatic system • Identify lymph node structures • Identify lymph nodes commonly palpated in the dog and cat Lymph • 2nd largest component of the immune system • Responsible for returning excess interstitial fluid back to the cardiovascular system Lymphatic System • Series of vessel or ducts that carries excess fluid to the blood vessels near the heart • The fluid is then put back into the blood stream • The fluid carried is called lymph • Structures: – – – – – Lymph nodes Spleen Thymus Tonsils Gut associated lymph tissue (GALT) Malt-mucosa associated lymphatic vessels – Spleen – Thymus – Tonsils – Galt • Gut associated lymph tissue • Peyer’s patches Lymph • Begins as excess tissue fluid that has been picked up by lymph capillaries • The reason there is more excess tissue fluid is that more fluid leaves the blood capillaries than reenters them • Lymph is carried through lymph vessels and deposited back into blood stream – Thoracic duct Part of Immune System 2 separate parts of animal’s immune system • System of ducts and fluid lymph – system picks up fluid leaked from capillaries – lymph ducts carry lymph to blood vessels near heart – lymph is put back into bloodstream • System of lymphoid organs and tissues – lymph nodes, spleen, thymus, tonsils, GaltPeyer’s patches Lymph Formation • Lymph starts out as excessive tissue fluid • Capillaries in the tissue join to form larger vessels to propel lymph toward the heart • Lymph eventually joins bloodstream Characteristics of Lymph Fluid • Transparent or translucent liquid • Contains varying numbers of cells – primarily lymphocytes • Different from plasma – more water, sugar, and electrolytes – fewer of the larger proteins found in plasma • Lymph from digestive system = chyle – postprandial lipemia Formation & Movement • Excessive interstitial fluid is picked up by small lymph capillaries – fluid enters/leaves tissue spaces due to blood pressure and osmotic pressure • Lymph capillaries join together to form larger and larger lymph vessels – one-way valves and body movements propels lymph toward the heart – lymph passes through at least one lymph node and picks up lymphocytes • Macrophages in lymph node remove microorganisms • Lymph is eventually emptied into thoracic duct – Located just before vena cava enters the right atrium • Lymph has come full circle – originated in plasma – has returned to plasma Comparments 2 classifications • Primary (Central lymphoid organs) – thymus • Secondary (Peripheral) – spleen – lymph nodes – Tonsils – Galt Thymus • Located in cranial thoracic region – most prominent in young animals • Produces mature T-cells from precursors sent from the bone marrow • Cells leave thymus and travel to secondary lymphoid tissue – important in stimulating cell-mediated immune response Secondary • • • • • Spleen Tonsil Lymph nodes Galt Main function – trap and process antigens and mature lymphocytes that mediate immune responses Function of Lymph • • • • Removal of excess tissue fluid Waste material transport Filtration of lymph Protein transport Lymphatic Structures Lymph Nodes • Small, kidney bean-shaped filters located along lymphatic vessels • Trap antigens and other foreign materials in lymph Copyright © 2016 by Elsevier, Inc. 17 • Found throughout the body • Drain organs in their associated locations • Can give clue to health of an animal – nodes more easily palpated when enlarged in response to antigenic stimulation – Fine Needle Aspirate (FNA) and cytology for evaluation for abnormalities Lymph nodes • • • • • Submandibular Prescapular Axillary Inguinal Popliteal Spleen • Tongue-shaped organ located on the left side of the abdomen – near stomach in simple-stomached animals • Covered with capsule of fibrous connective tissue and smooth muscle – smooth muscle cells contract and squeeze blood out of spleen and back into circulation Spleen • Acts as a reservoir for blood when animal is at rest – spleen gets larger when storage spaces are filled with blood • When body needs excess blood cells: – contract – blood is squeezed back into circulation – spleen gets smaller • Not essential for life • Tonsils – Peripheral lymphoid tissue – function to prevent spread of infection into respiratory and digestive systems – found close to moist epithelial surfaces – found at beginning of lymph drainage system • GALT (gut associated lymph tissue) – Refers to lymph tissue found in the lining of the intestinal tract – 25% of the intestinal mucosa is GALT Review • Describe the anatomy of the lymph system • What is the function of the lymphatic system • Describe how lymph is removed and transported • Describe the physical characteristics of lymph • Describe the role the different areas of the lymphatic system