Lymphatic System PDF

LYMPHATIC SYSTEM Romel M. Durante, RN, MAN ( C ) Clinical Instructor  Functions of the Lymphatic System 1. Fluid balance About 30 liters (L) of fluid pass from the blood capillaries into the interstitial spaces each day; only 27 L pass from the interstitial spaces back into th...

LYMPHATIC SYSTEM Romel M. Durante, RN, MAN ( C ) Clinical Instructor  Functions of the Lymphatic System 1. Fluid balance About 30 liters (L) of fluid pass from the blood capillaries into the interstitial spaces each day; only 27 L pass from the interstitial spaces back into the blood capillaries the 3 L of fluid enters the lymphatic capillaries, where it is called lymph (limf), and it passes through the lymphatic vessels to return to the blood. 2. Fat/Lipid Absorption The lymphatic system absorbs lipids and other substances from the digestive tract through lymphatic vessels called lacteals located in the lining of the small intestine. The lymph passing through these lymphatic vessels appears white because of its lipid content and is called chyle. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Functions of the Lymphatic System 3. Defense Pathogens, such as microorganisms and other foreign substances, are filtered from lymph by lymph nodes and from blood by the spleen. lymphocytes and other cells are capable of destroying pathogens. lymphatic system is involved with fighting infections, as well as filtering blood and lymph to remove pathogens. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Figure 14.1 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Components Lymph: fluid that enters lymphatic capillaries composed of water and some solutes Lymphocytes Lymphatic vessels Lymph nodes Tonsils Spleen Thymus gland Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Lymphatic Capillaries and Vessels Carries fluid in one direction from tissues to circulatory system Fluid moves from blood capillaries into tissue spaces Lymphatic capillaries: - tiny, closed-ended vessels - fluid moves easily into - in most tissues - join to form lymphatic vessels Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Lymphatic vessels: - resemble small veins - where lymphatic capillaries join - one-way valves Right lymphatic duct: - where lymphatic vessels from right upper limb and right head, neck, chest empty - empties into right subclavian vein Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Thoracic duct: - rest of body empties from lymphatic vessels - empties into left subclavian vein Copyright © McGraw-Hill Education. Permission required for reproduction or display. Lymph Formation and Movement Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Lymphatic Organs Tonsils: - palatine tonsils on each side of oral cavity - pharyngeal tonsils near internal opening of nasal cavity (adenoid) - lingual tonsils posterior surface of tongue - form a protective ring of lymphatic tissue around nasal and oral cavities Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Figure 14.3 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Lymph nodes: - rounded structures that vary in size - located near lymphatic vessels - groin, armpit, neck - lymph passes through lymph nodes before entering blood - lymph moves through and immune system is activated (lymphocytes produced) if foreign substances are detected - removal of microbes by macrophages Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Lymph Node Arrows indicate direction of lymph flow. As lymph moves through the sinuses, phagocytic cells remove foreign substances. the germinal centers are sites of lymphocyte production. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Spleen: - size of clenched fist - located in abdomen - filters blood - detect and respond to foreign substances - destroy old red blood cells - blood reservoir - white pulp: lymphatic tissue surrounding arteries - red pulp: contains macrophages and red blood cells that connect to veins Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Spleen Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Thymus gland: - bilobed gland - located in mediastinum behind the sternum - The thymus is the site for the maturation of a class of lymphocytes called T cells - produces and matures lymphocytes Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Figure 14.6a Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Immunity What is it? - ability to resist damage from foreign substances (Ex. Microbes, toxins, cancer cells) Types of immunity: - innate - adaptive Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Innate Immunity What is it? - present at birth - defense against any pathogen - accomplished by physical barriers, chemical mediators, cells, inflammatory response Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Physical Barriers First line of defense Skin and mucous membranes to act as barriers Tears, saliva, urine wash away pathogens Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Chemical Mediators What are they? chemicals that can kill microbes and prevent their entry into cells Lysozyme: found in tears and saliva to kill bacteria Mucous membranes: prevent entry of microbes Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Histamine: promote inflammation by causing vasodilation Interferons: proteins that protect against viral infections by stimulating surrounding cells to produce antiviral proteins Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Cells White blood cells: produce in red bone marrow and lymphatic tissue that fight foreign substances Phagocytic cells: - ingest and destroy foreign substances - Ex. neutrophils and macrophages Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Neutrophils: first to respond to infection but die quickly Macrophages: - monocytes - leave blood and enter tissues - can ingest more than neutrophils - protect lymph in lymph nodes and blood in spleen and liver - given specific names for certain areas of body (Kupffer cells in liver) Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Basophils: - made in red bone marrow - leave blood and enter infected tissues - can release histamine Mast cells: - made in red bone marrow - found in skin, lungs, gastrointestinal tract, urogenital tract - can release leukotrienes Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Eosinophils: - produced in red bone marrow - release chemicals to reduce inflammation Natural Killer Cells: - type of lymphocyte - produce in red bone marrow - recognize classes of cells such as tumor cells or virus infected cells - release chemicals to lysis cells Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Inflammatory Response What is it? involves chemical and cells due to injury signaled by presence of foreign substance stimulates release of chemical mediators Local inflammation is an inflammatory response confined to a specific area of the body. Symptoms: redness, heat, and swelling due to increased blood flow and increased vascular permeability, as well as pain caused by swelling and by chemical mediators acting on pain receptors. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Inflammatory Response Systemic inflammation is an inflammatory response that is generally distributed throughout the body. In addition to the local symptoms at the sites of inflammation, three additional features can be present: 1. Red bone marrow produces and releases large numbers of neutrophils, which promote phagocytosis. 2. Pyrogens (fever-producing), chemicals released by microorganisms, neutrophils, and other cells, stimulate fever production. Pyrogens affect the body’s temperature regulating mechanism in the hypothalamus in the brain. Fever promotes the activities of the immune system, such as phagocytosis, and inhibits the growth of some microorganisms. 3. In severe cases, vascular permeability can increase so much that large amounts of fluid are lost from the blood into the tissues. The decreased blood volume can cause shock and death. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Figure 14.8 Inflammatory Response Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Adaptive Immunity What is it? - defense that involves specific recognition to a specific antigen - acquired after birth - reacts when innate defenses don’t work - slower than innate immunity - has memory - uses lymphocytes (B and T cells) - 2 types: antibody-mediated and cell- mediated Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Terms Related to Adaptive Immunity Antigen: - substance that stimulates immune response - Ex. Bacteria, virus, pollen, food, drugs, etc. Self-antigen: molecule produced by person’s body that stimulates immune system response Antibody: proteins the body produces in response to antigen Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Origin and Development of Lymphocytes Stem cells: - red bone marrow - give rise to all blood cells - give rise to some pre T cells and pre B cells Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Lymphocytes: - type of white blood cell - involved in adaptive immunity - develop from stem cells - differentiate into specific lymphocytes such as B or T cells 34 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  B cells: - type of lymphocytes - involved in antibody-mediated immunity - originate from stem cells - mature in red bone marrow - move to lymphatic tissue after mature - lead to production of antibodies 35 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  T cells: - type of lymphocyte - involved in cell-mediated immunity primarily and antibody-mediated immunity - mature in thymus gland - move to lymphatic tissue after mature 36 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Figure 14.9 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Antigen Recognition Lymphocytes have antigen receptors on their surface Called B-cell receptors on B cells and T-cell receptors on T cells Each receptor only binds with a specific antigen When antigen receptors combine with antigen the lymphocyte is activated and adaptive immunity begins Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Major histocompatibility complex molecule (MHC): - contain binding sites for antigens - specific for certain antigens - hold and present a processed antigen on the surface of the cell membrane - bind to antigen receptor on B or T cells and stimulate response Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Cytokines: - proteins secreted by a cell that regulates neighboring cells - Ex. Interleukin 1 released by macrophages stimulates helper T cells Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Lymphocyte Proliferation 1. After antigen is processed and present to helper T cells, helper T cell produces interleukin-2 and interleukin 2-receptors 2. Interleukin-2 binds to receptors and stimulates more helper T cells production 3. Helper T cells are needed to produce B cells 4. B cells produce antibodies Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Proliferation of B Cells Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Dual Nature of Immune System Lymphocytes give rise to 2 types of immune responses: antibody-mediated and cell mediated Antigens can trigger both types of responses Both types are able to recognize self vs. non-self, use specificity, and have memory 43 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Antibody-Mediated What is it? - effective against antigens in body fluids (blood and lymph) - effective against bacteria, viruses, toxins - uses B cells to produce antibodies 44 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Antibody Structure Letter Y shape Variable region: - V of Y - bind to epitopes of antigen using antigen- binding site Constant region: - stem of Y - each class of immunoglobulin has same structure 45 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Structure of an Antibody Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Antigen-binding site: site on antibody where antigen binds Valence: number of antigen-binding sites on antibody 5 immunoglobulins used to destroy antigens: IgG, IgM, IgA, IgE, IgD 47 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Effects of Antibodies Inactivate antigen Bind antigens together Active complement cascades Initiate release of inflammatory chemicals Facilitate phagocytosis Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Figure 14.13 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Antibody Production Primary response 1st exposure of B cell to antigen B cell undergoes division and forms plasma cell and memory cells Plasma cells: - produce antibodies - 3-14 days to by effective against antigen - person develop disease symptoms Copyright © McGraw-Hill Education. Permission required for reproduction or display. Secondary Response Memory cells: - occurs when immune system is exposed to antigen that has been seen before - B memory cells quickly divided to form plasma cells which produce antibodies - produces new memory cells Copyright © McGraw-Hill Education. Permission required for reproduction or display. Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Cell-Mediated Immunity What is it? - effective against antigens in cells and tissues - effective against bacteria, viruses, fungi, and protozoa - uses different types of T cells 54 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Types of T cells Helper T cells (TH): - activate macrophages - help form B cells - promote production of Tc 55 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Cytotoxic T cells (Tc): precursor to cytotoxic T lymphocytes (CTL) Cytotoxic T lymphocytes (CTL): destroys antigen on contact Regulatory T cells (Tr): turn off immune system response when antigen is gone 56 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Stimulation and Effects of T Cells Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Types of Adaptive Immunity Naturally Acquired Immunity Active: ✓natural exposure to antigens causes production of antibodies ✓Because the individual is not immune during the first exposure, he or she usually develops the symptoms of the disease. Passive: - transfer of antibodies from mother to child - Ex. Breast milk or placenta 58 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Artificially Acquired Immunity Active: - injection of antigens using vaccines which cause the production of antibodies - vaccine or immunization: process of introducing killed, live, or inactivated pathogen 59 Copyright © McGraw-Hill Education. Permission required for reproduction or display. Artificially Acquired Immunity Passive: ✓ injection of antibodies from another person or animal. ✓ begins with vaccinating an animal, such as a horse. After the animal’s immune system responds to the antigen, antibodies are removed from the animal and injected into the human requiring immunity. ✓ Antibodies that provide passive artificial immunity are referred to by the general term antiserum because the antibodies are found in serum, which is plasma minus the clotting factors. ✓ Antisera are available against microorganisms that cause disease, such as rabies, hepatitis, and measles; bacterial toxins, such as those that cause tetanus, diphtheria, and botulism; and venoms from poisonous snakes and spiders. 60 Copyright © McGraw-Hill Education. Permission required for reproduction or display.  Figure 14.18 Copyright © McGraw-Hill Education. Permission required for reproduction or display.