PowerPoint ® Lecture Slide Presentation by Patty Bostwick-Taylor, Florence-Darlington Technical College Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings PART A 12 The Lymphatic System and Body Defenses
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Lmphatic System Two major categories Non-specific Immunity Do not act on a specific antigen or invader, but provides a general defense by acting on anything not itself Specific Immunity Recognizes specific threatening agents and targets these agents only
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings The Lymphatic System Consists of two semi-independent parts Lymphatic vessels- structure Transports escaped fluids back to the blood-function Lymphoid tissues and organs- structure Plays essential roles in body defense and resistance to disease-function
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Lymphatic Characteristics Lymph—excess tissue fluid carried by lymphatic vessels Excess tissue fluid accumulation is called edema Lymphatic vessels (lymphatics) forms one way system toward the heart Lymph capillaries- weave between the tissue and the blood capillaries in tissues of the body
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Lymphatic Vessels Lymph capillaries Walls overlap to form flap-like minivalves Fluid leaks into lymph capillaries Capillaries are anchored to connective tissue by filaments Higher pressure on the inside closes minivalves Fluid is forced along the vessel
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Relationship of Lymphatic Vessels to Blood Vessels Figure 12.1
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Lymphatic Vessels Figure 12.2a
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Lymph Harmful materials that enter lymph vessels, but can’t enter lymph capillaries Bacteria Viruses Cancer cells Cell debris Lymph takes a detour through the lymph nodes to clean it of debris and be examined by immune system.
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Lymphatic Vessels Lymphatic collecting vessels Collect lymph from lymph capillaries Carry lymph to and away from lymph nodes Return fluid to circulatory veins near the heart Right lymphatic duct- drains lymph from right arm, right side of head and thorax Thoracic duct- drains lymph from rest of body
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.3 Lymphatic Vessels
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Properties of Lymphatic Vessels One way system towards the heart No pump Lymph moves toward the heart Milking action of skeletal muscle Rhythmic contraction of smooth muscle in vessel walls
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Lymph Nodes Filter lymph before it is returned to the blood Defense cells within lymph nodes Macrophages—engulf and destroy foreign substances Lymphocytes—provide immune response to antigens (a foreign substance) Lymphocytes are a type of white blood cells Swollen glands are actually swollen lymph nodes
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Lymph Nodes Figure 12.3
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Lymph Nodes To Know Cervical Nodes- neck Axillary Nodes- under the arm Inguinal Nodes- upper femor
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Lymph Node Structure Most are kidney-shaped and less than 1 inch long Cortex Outer part Contains follicles—collections of lymphocytes Medulla Inner part Contains phagocytic macrophages
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.4 Lymph Node Structure
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Flow of Lymph Through Nodes Lymph enters the convex side through afferent lymphatic vessels Lymph exits through efferent lymphatic vessels Fewer efferent than afferent vessels causes flow to be slowed Lymph passes through several nodes before the cleaning process is complete.
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Other Lymphoid Organs Several other organs contribute to lymphatic function Spleen Thymus Tonsils Peyer’s patches Only lymph nodes filter lymph
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Spleen Located on the left side of the abdomen Filters blood, not lymph Destroys worn out blood cells Most important functon Forms blood cells in the fetus, hematopoietic site Acts as a blood reservoir, will release blood during hemorrhaging
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Other Lymphoid Organs Figure 12.5
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Thymus Gland Located low in the throat, overlying the heart in the mediastium Functions at peak levels only during childhood Largest during childhood Can be largely replaced with fat in advanced age Produces hormones (like thymosin) to program lymphocytes
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Tonsils Small masses of lymphoid tissue around the pharynx Trap and remove bacteria and other foreign materials Tonsillitis is caused by congestion with bacteria
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Other Lymphoid Organs Figure 12.5
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Peyer’s Patches Found in the wall of the small intestine Resemble tonsils in structure Capture and destroy bacteria in the intestine so they don’t penetrate intestinal wall
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Mucosa-Associated Lymphatic Tissue (MALT) Includes Peyer’s patches Tonsils Other small accumulations of lymphoid tissue Acts as a sentinel to protect respiratory and digestive tracts