Lymphatic System Study Guide – Flashcards
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Pathogenic
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capable of causing disease
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Immune System
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not an organ system, but a cell population that inhabits all organs and defends the body from agents of disease
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Lymphatic System
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Network of organs and vein-like vessels
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Functions of Lymphatic System
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Fluid recovery- Fluid continually filters from the blood capillaries into the tissue spaces. Immunity-Excess filtered fluid picks up foreign cells and chemical from tissue Lipid absorption- lacteals in small intestine absorb dietary lipids that are not absorbed by the blood capillaries
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Components of Lymphatic System
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Lymph- recovered fluid Lymphatic vessels- transport the lymph Lymphatic tissues- Composed of aggregates of lymphocytes and macrophages that populate many organs in the body Lymphatic organs- defense cells are especially concentrated in these organs; separated from surrounding organs by connective tissue capsules
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6 Lymphatic ducts
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~Drain major portions of the body jugular subclavian bronchomediastinal intercostal intestinal lumbar
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2 Collecting ducts
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right lymphatic duct- union of right jugular, subclavian and bronchomediastinal lymphatic trunks thorarcic duct- on left side, larger and longer; receives lymph from below diaphragm, left arm, left side of head, neck and thorax
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Mechanism of Lymph Flow
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lymph flows at low pressure and speed Valves prevent backward flow moved along primarily by rhythmic contractions Flow aided by skeletal muscle pump
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Lymphatic (lymphoid) Tissue
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aggregations of lymphocytes in mucous membranes and various organs
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Diffuse lymphatic tissu
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simplest form, prevalent in body passages open to the exterior
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Lymphatic Nodules
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dense masses of lymphocytes and macrophages that congregate in response to pathogens
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Primary Lymphatic Organs
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red bone marrow and thymus; site where T & B cells become immunocompetent
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Secondary Lymphatic Organs
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lymph nodes, tonsils and spleen
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Red Bone Marrow
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involved in hemopoiese (blood formation), immunity,
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Thymus
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large in fetus, after 14 yrsold begins involution Member of both the endocrine and lymphatic systems, Contains developing t-lymphocytes, secretes hormones that regulate T-cell development
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Lymph Node
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organs that filter lymph and act as a site of T and B cell activation
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Palatine tonsils
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pair at posterior margin of oral cavity; most often infected
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Lingual tonsils
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pair at the root of tongue
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Pharyngeal tonsil
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(adenoids) single tonsil on the back wall of the nasopharynx
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Tonsillitis
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inflammation of the tonsils
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Spleen
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inferior to diaphragm, dorsal to stomach; Function: blood production in fetus, blood reservoir, RBC disposal, immune reactions- filters blood, quick to detect antigens
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3 Lines of Defense against Pathogens
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First line: skin & mucus membranes Second line (nonspecific defense): leukocytes and macrophages, antimicrobial proteins, immune surveillance, inflammation and fever Third line: the immune system
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Nonspecific Defenses
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broadly effective, no prior exposure, external barriers, inflammation and fever
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Specific Defense
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results from prior exposure, protects against only a particular pathogen, immune system
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Phagocyte
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A cell, such as a white blood cell, that engulfs and absorbs waste material, microorganisms or other foreign bodies in the bloodstream and tissues
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5 main types of Leukocytes
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Neutrophils Eosinophils Basophils Monocytes Lymphocytes
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Neutrophils
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Wander in tissues and phagocytize bacteria, create killing zone
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Eosinophils
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Found in mucous membranes, phagocytize antigen-antibody complexes, allergens and inflammatory chemicals a; block excess inflammation; limit histamine
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Basophils & Mast Cells
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A cell such as WBC that engulfs and absorbs waste material
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Histamine
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^ blood flow to infected tissue
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Heparin
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Prevents immobilization of phagocytes
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Leukotrienes
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Activate and attract other leukocytes
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Monocytes
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Move from blood into connective tissues and transform into macrophages
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Wandering Macrophages
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Actively seek pathogens , widely distributed in loose connective tissue
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Fixed macrophages
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Only phagocytize pathogens that come to them
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Interferons
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Polypeptides secreted by cells invaded by viruses
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4 methods of pathogen destruction
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Inflammation Immune clearance Phagocytosis Cytolysis
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Membrane Attack Complex
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Complement proteins form ring in plasma membrane of target cell causing cytolysis
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Immune Surveillance
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A phenomenon in which natural killer (NK) cells continually patrol the body on the lookout for pathogens and diseased host cells
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Pyrogen
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Fever producing agents; attacking neutrophils and macrophages secrete chemicals, interleukins, interferons, and others that act as endogenous pyrogens
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Antipyretics
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Fever reducing medications inhibit PGE2
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3 stages of fever
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Onset: body temperature rises Stadium: body temperature oscillates around new set point Defervescence: body temperature returns to normal
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Reye syndrome
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Serious disorder in children younger than 15 following an acute viral infection such as chicken pox or flu Swelling of brain neurons, fatty infiltration of liver and other viscera
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Inflammation
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Limits spread of pathogens, destroys them, removes debris, initiates tissue repair Signs: redness, swelling, heat, pain
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-itis
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Denotes inflammation of specific organs
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-algia
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Pain
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Cytokines
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Class of chemicals that regulates inflammation and immunity
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3 major processes of inflammation
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Mobilization of body defenses Containment and destruction of pathogens Tissue cleanup and repair
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Mobilization of Defense
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Most immediate requirement for dealing with tissue injury is to get the defensive Leukocytes to the site quickly.
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Hyperemia
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Increased blood flow; washes toxins and metabolic waste from the site more rapidly
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Margination
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Leukocytes adhere to blood vessel wall
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Diapedesis
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Leukocytes crawl through gaps in the endothelial cells and enter tissue fluid
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Capillary permeability
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Fluid, Leukocytes and plasma proteins leave the bloodstream
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Process of containment and destruction phase
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Prevent the spread of pathogens throughout the body
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Fibrinogen
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Filters into tissue fluid gets activated to form fibrin; forms sticky mesh that walls off microbes
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Heparin
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Prevents clotting at site of injury
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Chemotaxis
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Attraction to chemicals such as bradykinin and leukotrienes that guide them to the injury site
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How does Edema contribute to tissue cleanup
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Compresses veins and reduces venous drainage; forces open valves of lymphatic capillaries promoting lymphatic drainage; lymphatics collect and remove bacteria, dead cells, proteins, and tissue debris better than blood capillaries.
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Specificity immunity
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Immunity directed against a particular pathogen
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Memory immunity
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When re exposed to the same pathogen the body reacts so quickly that there is no noticeable illness.
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Humoral immunity
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Antibody mediated. B cells indirect attack where antibodies neutralize the pathogen; can only work against extra cellular stage of infectious microorganisms
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Cell-mediated immunity
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T cells. Lymphocytes directly attack and destroy foreign cells or diseased host cells; means of ridding body of pathogens that reside inside human cells where they are inaccessible to antibodies.
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Natural Active immunity
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Produces memory cells; production of ones own antibodies or T cells as a result of infection or natural exposure to antigen
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Artificial Active immunity
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Production of ones own antibodies or T cells as a result of vaccination
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Natural Passive immunity
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Through placenta, milk; fetus or infant acquired antibodies from mother; temporary
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Artificial Passive immunity
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Injection of immune serum from another individual/organism; snakebite, rabies, tetanus; temporary
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Major cells of immune system
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T lymphocytes (T cells) B lymphocytes (B cells) Dendritic cells Reticular cells
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T lymphocytes
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Mature in thymus
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B lymphocytes
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Activations cause proliferation and differentiation into plasma cells that produce antibodies
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Dendritic cells
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Alert immune system to pathogens that have beached their surface
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Reticular cells
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Branched stationary cells that contribute to the storma of lymphatic organs
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Immunocompetent
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Capable of recognizing antigens presented to them by APCs
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Two forms of negative selection
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Colonial deletion- self reactive T cells die and macrophages phagocytize them Anergy- self reactive T cells remain alive but unresponsive
