Lymphatic System L Y M P H A T I C C O M P O N E N T S What is a Lymphatic System? The lymphatic system is a complex system of fluid drainage and transport, immune response, and disease resistance. Fluid that is forced out of the bloodstream during normal circulation is filtered through lymph nodes to remove bacteria, abnormal cells and other matter. This fluid is then transported back into the bloodstream via the lymph vessels. Lymph only moves in one direction, toward the heart. Return tissue fluid to the bloodstream (fluid balance) Immunity Functions Transport fats from the digestive tract to the bloodstream 1
Lymphatic Vessels Resemble veins in structure Connect to lymph nodes at various intervals, but begin blindly in the intercellular spaces of the soft tissues. They do NOTform a closed circuit. Ultimately deliver lymph into 2 main channels Right lymphatic duct Drains right side of head & neck, right arm, right thorax Thoracic duct Drains the rest of the body Biggest lymphatic vessel! Lymphatic Vessels Lymph: Clear, watery-appearing fluid which resembles blood plasma but has a lower % of protein. It is found in the lymphatic vessels. Interstitial Fluid: Complex fluid which fills the spaces between cells. Lymph Tissue 1. Diffuse lymphatic tissue No capsule present Found in connective tissue of almost all organs 2. Lymphatic nodules No capsule present Oval-shaped masses Found singly or in clusters 3. Lymphatic organs Capsule present Lymph nodes, spleen, thymus gland Lymph Nodes There are lymph nodes you can feel in your armpits, in your groin at the top of your legs, and in your neck. There are lymph nodes you cannot feel in your abdomen, pelvis, and chest. 2
Swollen lymph nodes, sore throat, fatigue and headache are some of the symptoms of mononucleosis which is caused by the Epstein-Barr virus. Most patients recover in 4-6 weeks without medication. Tonsils Multiple groups of large lymphatic nodules located on the mucous membrane of the oral and pharyngeal cavities. Palatine Posterior-lateral walls of oropharynx Pharyngeal(Adenoids) Posterior wall of nasopharynx Lingual Base of tongue 3
(Palatine) The palatine tonsils are the ones we see at the back of the throat. Largest lymphatic organ! Spleen Thymus Gland Located below the diaphragm, behind the stomach, and above the left kidney Functions: Filters blood macrophages remove microorganisms Hematopoiesis monocytes& lymphocytesfinish their development here Red blood cell & platelet destruction Stores blood Located behind the sternum Functions in differentiation and maturation of T cells 4
Immune System Nonspecific Defense Mechanisms Defends against harmful organisms, chemicals, and tumors. 2 types of defense Nonspecific Specific Interferon: protein made by certain cells and released into circulation if invaded by viruses. Inflammationis a non-specific defense mechanism. Specific Defense Mechanisms Antigen specificity; self/non-self recognition; immunological memory Antibody-mediated Immunity (Humoral) B cells become plasma cells which produce antibodies that bind with specific antigens. Cell-mediated Immunity T cells directly destroy foreign cells. Phagocytosis is a non-specific defense mechanism too! 5
Antibody-mediated Immunity (Humoral) Sensitized B-cell Primary response Memory B-cells Subsequent antigen meetings 5 Classes of Antibodies IgM produced for initial contact with antigen; first secreted during primary response IgG major antibody of the secondaryresponse; found in plasma Plasma cells secrete Antibodies Secondary response IgA predominant antibody in mucous membranes, tears, saliva, and mother s milk IgE small amount; involved in allergies: promotes the release of histamine by mast cells IgD small amount; exact function is unknown Cell-mediated Immunity Sensitized T-cell Helper Killer Suppressor Memory Activate B-cells Directly contact and kill target Slow or stop the activity of B and T cells Persist to provide for secondary responses; Circulate in blood & lymph 6
HIV Human immunodeficiency virus is a retrovirusthat primarily infects the human immune system, specifically CD4 + T cells (Helper ) AIDS! The HIV infection cycle: The cycle begins and ends with free HIV particles present in the bloodstream of its human host. These free viruses infect white blood cells that have CD4 receptors (CD4 + cells). Attachment Entry into macrophages Replication Entry into T cells The Future of HIV Treatment 1. Combination Therapy Use of 2 drugs AZT which blocks replication of the virus and protease inhibitors to block the production of vital proteins. 2. Vaccine - using defective viral gene nef Drug Therapy to inhibit nef s protein product 3. Blocking receptors 4. Disabling receptors 5. Blocking replication with CAF(an antiviral factor) 7