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The Lymphatic System The Lymphatic System Series of vessel/ducts – Carry excess tissue fluid to blood vessel Structures – Lymph nodes – Spleen – Thymus – Tonsils – Gut-associated lymph tissue (GALT) The Lymphatic System Lymph= the fluid carried in the vessels – Cellular componentlymphocytes Lymph Formation Excess Tissue Fluid=more fluid leaves blood capillaries, than is coming back Arterial end of capillary-plasma leaves the capillaries due to pressure – Plasma delivers nutrients, oxygen, hormones to bathe cells – Fluid now in Interstitial space Lymph formation Venous end of the capillaries – Blood pressure drops, so not pushing plasma out of capillary – Proteins still within capillaries-Increases oncotic pressure pulls fluid back into the capillary (this force is not as strong normally as BP lymph is formed) – Lymphatics collect excessive fluid – (Also can collect tumor cells, BT, proteins ) Lymph formation-gone wrong! What happens with low protein levels? What happens with high venous pressure?? Lymphedema Lymph Capillaries Lymph capillaries start as blind ended structures. Smaller lymph vessels come together to form larger vessels Lymphatic Circulation Vessels contain one way valvesprevent backward flow Vessels ultimately return to the circulation via Thoracic ducts Lymphatics are not located in CNS and avascular structures such as cartilage, bone and teeth Thoracic Duct Lymphatic Circulation Lymphatic Circulation Lymphatic vessels from the hindend drain into Cisterna chyli in cranial abdomen. Then joins the Thoracic Duct. Where does the Thoracic duct join the circulation? All lymphatic vessel travel through at least one lymph node Lymph Composition – More water, sugar, electrolytes than plasma – Less of the large proteins (albumin, globulin and fibrinogen) than plasma Chyle = lymph from the digestive system – After meals-contains fat (chylomicrons) Increased fat in the plasma after meal = Lipemia Lipemia Function of the Lymphatic System Removal of excess tissue fluid Waste material transport-cellular waste Filtration of lymph-microorganisms, cell debris, foreign material>before it enters the bloodstream Protein Transport-large proteins in interstitium can’t reabsorb into blood capillaries Lymph Nodes Drain specific areas of the body Structure – CT capsule – Afferent vessels-enter – Efferent vessels-exit – Cortex and medulla Cortex-location of lymphocytes clustered in Lymph nodules Medulla-macrophage located (filter) Lymph Node Anatomy Lymph node palpation Popliteal ln. Mandibular ln. Fine Needle Aspiration Inguinal ln. Prescapular ln. Axillary ln. Lymphoma Lymphosarcoma Tumor of the lymph node system Spleen Lymphatic and Hematological function ****Left side of the abdomen**** Connective tissue capsule surrounded by smooth muscle Trabeculae (branches of the capsule) sent into tissue of the spleen – Contains blood vessels, nerves, smooth muscle and lymph vessel Spleen Spleen Splenic contraction-contraction of the smooth muscle (carnivores>ruminants) Squeezes blood into circulation!!! – HBC! Spleen Interior of spleen – Red pulp-blood vessels and macrophages – White pulp-area of lymphoid tissue Lymphocytes –clonal division when needed Function of the Spleen Blood storage in red pulp Removal of foreign material-by macrophages in red pulp Removal of dead, dying and abnormal RBC’s-macrophages in red pulp Lymphocyte cloning-in white pulp ***Not essential for life*** Good thing it is not essential!! Splenic mass-hemangioma vs. Hemangiosarcoma Splenectomy to remove mass Thymus Found in Cranial Thoracic region – Found on either side of the trachea – Found in young animals then shrinks – Processes T lymphocytes to “kick start” developing immune system Thymus Tonsils Tonsils - This lymphoid tissue encircles the pharynx and screens pathogens entering in air or food. – Palatine - Palate – Pharyngeal - Nasopharynx – Lingual - Base of tongue Gut-Associated Lymph Tissue Lymphatic tissue found in the lining of the GI tract -largest lymphoid organ – if all put together! – Similar to Bursa of Fabricius in bird intestines Process B lymphocytes Peyers patches - aggregates of lymphoid follicles Ileum of the intestines Clinical Why remove a lymph node near a cancer site? – That is where cancerous cells/antigens will be brought if the tumor is metastasizing. Removal of a lymph node causes localized edema. Why? – There is decreased removal of interstitial fluid until the vessels from a nearby lymph node grow into the area. Why do spleens rupture so easily? – Their capsules are very thin. Immune System Function Protect the animal from anything that could cause disease or damage! Must recognize “self” vs. “foreign invader” – Detects surface proteins Antigen Mechanisms to destroy foreign matter Phagocytosis and destruction of foreign cells Lysis of foreign cell membranes Inactivation of organism or chemical substances Clumping (agglutination) of cells Excessive Immune Response Immune mediated disease Anaphylaxis (excessive allergic reaction) Introduction to WBCs Neutrophilsphagocytosis EosinophilsAllergic reaction Basophils-initiates Immune and allergic reactions Introduction to WBCs Lymphocytes B T NK MonocytePhagocytosis Nonspecific ImmunityRapid response Barrier tissues-??? Inflammation Phagocytosis Natural killer (NK) cells-type of lymphocyte that kills cancer cells and viruses Interferon-protein produced by cell infected by virus, trying to prevent spread Complement-enzymes in plasma that can cause rupture of cell membrane of foreign cell Specific Immunity Specific reactions to destroy specific antigens – Different viruses/but have different antigens Two types – Humoral immunity – Cell Mediated immunity Cell Mediated Immunity T lymphocytes attach to antigens on surface of the foreign cell Usually viruses, fungi, cancerous cells Process responsible for rejection of transplant tissue Humoral Immunity Function of the B lymphocyte B lymphocyte (plasma cell) produces antibodies (immunoglobulin) Activated B lymphocytes clonal division Become plasma cells produce only one type of Antibody for life IgG, IgA, IgE, IgM Just a little something to memorize!!! Memory Cells B or T lymphocytes that remember the foreign invader Next exposure greater response, faster!! Active immunity-Exposure to the antigen – Infection or Vaccination Passive immunity-Ab received from mothers milk This workforce solution was funded by a grant awarded under the Workforce Innovation in Regional Development (WIRED) as implemented by the U.S. Department of Labor’s Employment and Training Administration working in partnership with the Colorado Department of Labor and Employment, the Metro Denver Economic Development Corporation, and the City and County of Denver's Office of Economic Development. The solution was created by the grantee and does not necessarily reflect the official position of the U.S. Department of Labor. The Department of Labor makes no guarantees, warranties, or assurances of any kind, express or implied, with respect to such information, including any information on linked sites and including, but not limited to, accuracy of the information or its completeness, timeliness, usefulness, adequacy, continued availability, or ownership. 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