Lymphatic system Review PDF

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Lymphatic System Review ● Components of the lymphatic system ○ Lymph: After interstitial fluid passes into lymphatic vessels it’s called lymph ■ lymph is located within lymphatic vessels and lymphatic tissue. ○ Primary Lymphatic Organs ■ Spleen,Tonsils,Thymus,Bone Marrow, Lymph nodes and nodules ○ Lymphatic Vessels ■ lymphatic capillaries unite to form larger lymphatic vessels ■ One-way system (all vessels lead to heart) ■ Capillaries-> vessels-> nodes-> trunks-> ducts-> subclavian vein ● Closed ended tubes ● Located between cells ■ Found all over body ● Except avascular tissue (such as cartilage, the epidermis, and the cornea of the eye), portions of the spleen, and red bone marrow. ● Lacteals- in Gi tract ○ Deliver chyle to blood ○ Lymphatic Capillaries ■ Compared to blood vessels ● Slightly larger ● Greater permeability ● Anchoring filaments ● No basement membrane ● close -ended tubes ○ Lymphatic Trunks and Ducts ■ lymphatic vessels exit lymph nodes in a particular region of the body, they unite to form lymph trunks ■ principal trunks ● Lumbar: drain lymph from the lower limbs, the wall and viscera of the pelvis, the kidneys, the adrenal glands, and the abdominal wall ● Intestinal: drains lymph from the stomach, intestines, pancreas, spleen, and part of the liver ● bronchomediastinal:drain lymph from the thoracic wall, lung, and heart ● subclavian:drain the upper limbs. ● jugular trunks: drain the head and neck ■ Right Lymphatic Duct ● Formed by the merging of the trunks (Rights) ○ Jugular trunk

Lymphatic System Review ○ Subclavian trunk ○ Right lymphatic duct entering right subclavian vein ○ Right bronchomediastinal trunk ■ Thoracic Duct ● Collects lymph from the trunks ○ Left jugular trunk ○ Left subclavian trunk ○ Thoracic duct entering left subclavian vein ○ Left bronchomediastinal trunk ■ Cisterna Chyli ● Absorbed lipids ● “White” ● Bringing intersitial from liver ■ Right Lumbar and Left Lumbar trunk: where all lymph comes from ● Primary Lymphatic Organs ○ Primary lymphatic organs and organs where immune cells become immunocompetent (able to trigger an immune response) ■ Red Bone Marrow and Thymus ○ Bone Marrow ■ All formed elements except (T-lymphocytes) leave bone marrow and directly enter and circulate in blood) ○ Thymus ■ 2 lobed organ ■ Located in mediastinum ■ Functions: T cells maturation (Thymosin helps) ■ Educate naive T Cells (How they recognize any forgin) ■ If immune system can’t recognize body cells -> atherosclerosis ■ B cells directly attack antigens ■ Relatively large in children but shrinks/atrophies with age (replaced by adipose) ■ Thymus is biggest during puberty ● Secondary Lymphatic Organs and Tissues ○ Lymph Nodes ■ covered by a capsule of dense connective tissue that extends into the node ■ capsular extensions, called trabeculae, divide the node into compartments, provide support, and provide a route for blood vessels into the interior of a node ■ Functions: Filtrations of lymph, surveillance, and proliferation (rapid growth of B and T cells/ cells getting bigger)

Lymphatic System Review ■ Nodes filter lymph ■ Route of Lymph Flow through a Lymph Node ● Afferent lymphatic vessel subcapsular sinuses & trabecular sinuses medullary sinuses efferent vessels at hilum ■ Swollen lymph nodes indicate infection ○ Spleen ■ Largest lymphatic organ ■ Hilum/Hilus (blood and lymphatic vessels ■ Functions: Filters blood, engulf foregin particles defective worn out RBCs and platelets, stores platelets, site of fetal blood cell production ○ Lymphatic Nodules ■ Lymphatic tissue not surrounded by capsule ■ Mucosa-associated lymphoid tissue (MALT) ■ Peyer’s patches (lymphatic follicles) (GALT) ● Appendix ■ Tonsils ■ Walls of bronchi (BALT) ■ Antibiotics wipe off good bacteria ● Formation and Flow of lymph ○ nutrients, gases, and hormones, filter freely through the capillary walls to form interstitial fluid ○ excess filtered fluid—about 3 liters per day—drains into lymphatic vessels and becomes lymph ○ Interstitial fluid-> lymph capillaries -> lymph vessels -> lymph trunks-> lymph ducts-> subclavian veins ○ Lymph transport: ■ Valves ■ Skeletal “pump” (pulsation of arteries)- influence to pump blood upward ■ Respiratory “pump” ○ Efferent Lymphatic: carry lymph from lymph nodes ○ Lymph Nodes: substances through filtering lymph, phagocytosis, and immune reactions ○ Afferent Lymphatic: carry lymph from lymphatic capillaries to lymph nodes ● Ch 22: Immunity ○ Innate Immunity (1st line of Defense) ■ external physical and chemical barriers provided by the skin and mucous membranes

Lymphatic System Review ■ internal defenses, such as antimicrobial substances, natural killer cells, phagocytes, inflammation, and fever. (Inhibit spread of invaders throughout the body

● Second-Line of Defense ○ pathogens penetrate the physical and chemical barriers of the skin and mucous membranes, they encounter a second line of defense ○ internal antimicrobial substances, phagocytes, natural killer cells, inflammation, and fever. ○ Cells ■ Phagocytes: specialized cells (the ingestion of microbes or other particles such as cellular debris) ● 2 major types: Neutrophils and Macrophages ● infection occurs, neutrophils and monocytes migrate to the infected area ● Wandering Macrophages: migration, the monocytes enlarge and develop into actively phagocytic macrophages ● Fixed Macrophages: microglial cells not going anywhere ● Dendritic Cells: become langerhands ● Eosinophils: ■ Antimicrobial Proteins

Lymphatic System Review ● Interferon: IFNs diffuse to uninfected neighboring cells, where they induce synthesis of antiviral proteins that interfere with viral replication ● Complement:Causes cytolysis (bursting) of microbes, promotes phagocytosis, and contributes to inflammation. ● Transferrins: found in blood and tissue fluids ■ Natural Killer Cells (Nonspecifically kill forgien or unhealthy cell) ● lack the membrane molecules that identify B and T cells ● ability to kill a wide variety of infected body cells and certain tumor cells ● cells attack any body cells that display abnormal or unusual plasma membrane proteins ● Perforin( forms a transmembrane pore) and Granzyme (causes apoptosis of cell ■ Mast Cells ● Inflammation release Histamine ■ Inflammation ● an attempt to dispose of microbes, toxins, or foreign material at the site of injury, to prevent their spread to other tissues, and repair ● nonspecific, defensive response of the body to tissue damage ● Causes inflammation: pathogens, abrasions, chemical irritations, distortion or disturbances of cells, and extreme temperatures ● Signs and symptoms ○ P is for pain due to the release of certain chemicals. ○ R is for redness because more blood is rushed to the affected area. ○ I is for immobility that results from some loss of function in severe inflammations. ○ S is for swelling caused by an accumulation of fluids. ○ H is for heat which is also due to more blood rushed to the affected area. ■ Fever ● Abnormally high body temperature ● Occurs as hypothalamic thermostat rest via pyrogens(released by bacteria) ● Occurs during infection from bacteria ● Affects entire body ● High Fever= denature enzymes

Lymphatic System Review ● Increased metabolic rate speeds up tissue repair ○ Antimicrobial Proteins ■ Interferon: IFNs diffuse to uninfected neighboring cells, where they induce synthesis of antiviral proteins that interfere with viral replication ■ Complement:Causes cytolysis (bursting) of microbes, promotes phagocytosis, and contributes to inflammation. ■ Transferrins: found in blood and tissue fluids

● Adaptive Immunity 3rd Defense ○ Body's ability to defend itself against specific invading agents ○ B cells complete development in red bone marrow ○ Pre t-cells migrate to thymus and differentiate into (Helper T Cells or Cytotoxic T cells) ○ Specificity: recognition of particular antigens ○ Memory: remembers previously encountered antigens (acquire through exposure) ○ Systemic: immunity not restricted to the initial infection site ○ Involves lymphocytes B cells and T cells ○ 2 types of adaptive immunity

Lymphatic System Review ■ Cell mediated (T-cells): cytotoxic T cells directly attack invading antigens ■ Antibody-mediated (Humoral immunity): B cells transform into plasma cells, which synthesize and secrete specific proteins called antibodies ○ Antigen Presentation: ■ B cells recognize and bind to lymph,interstitial fluid,or blood plasma (native antigens)- attack invaders outside of cell ■ T cells only recognize fragments of antigenic proteins that are processed and presented a certain way (processed antigens)0attack infected cells ■ Antigenic proteins are broken down into peptide fragments that associate MHC molecules ■ Then the antigen-MHC complex is inserted into plasma membrane of cell ○ MHC 1&2 ■ MCH 1- endogenous (all body cells except RBC’s including APC’s) ■ MCH 2-exogenous (only on APC’s

● Structure of T cells and B cells ○ Immunocompetence- ability to carry out adaptive immune response ○ Have Ag receptors (TCR & BCR) to identify specific Ag ○ One Type of TCR or BCR per cells, but thousands of this specific BCR or TCR on each cell ○ CD (cluster of differentiation) proteins

Lymphatic System Review ● Clonal Selection ○ process by which a lymphocyte proliferates (divides) and differentiates (forms more highly specialized cells) in response to a specific antigen. ○ Each lymphocyte can only be activated by one antigen (divides repeatedly to form CLONES) ○ Memory Cells-carry out immune responses that ultimately result in the destruction or inactivation of the antigen ○ Effector Cells-do not actively participate in the initial immune response to the antigen (respond to the antigen by proliferating and differentiating into more effector cells and more memory cells) ● Antigens ○ Antigen: Molecule that provokes a specific immune response ○ Antigenic determinants (epitopes)- small parts of large antigen, each stimulating a different response ○ Characteristics of an antigen ■ Immunogenicity: ability to provoke an immune response ■ Reactivity: ability of the antigen to react specifically with the antibody or cells provoked ■ Hapten: smaller substance that has reactivity but lacks immunogenicity ■ Epitopes:Smaller immunogenic parts of a larger antigen ● Cell-Mediated Immunity ○ Antigen recognized and bound ○ Smaller number of T-cells ○ Antigen eliminated ● Activation and Clonal ○ Helper T cells become activated when they bind to a complex of MHC-II proteins and antigens presented by macrophages ○ Helper T cells secrete interleukin-2 ○ Helper T cells directly kill organism ○ Example: HIV targets helper T cells (the only virus that can attack helper T cells) ○ Cytotoxic T cell ■ Interleukin-2 stimulates production of cytotoxic T cells ■ Cytotoxic T cell whose receptor fits antigen-MHC protein complex begins to multiply rapidly ■ Any cells bearing traces of viral infection are destroyed ■ Activity- secret lethal proteins such as ● Perforins: increase cell permeability (cytolysis) ● Granulysin:Destroy microbes ● Granzymes: Induce apoptosis

Lymphatic System Review ● Antibody-Mediated Immunity ○ Antigen is recognized and bound ○ Helper T cells costimulate the B cell so the B cell can proliferate and differentiate into a clone of effector cells that produce antibodies ○ Antigen is eliminated ○ B cells remain in the 2 degree lymphatic tissue ● Antibodies (Ab)/Immunoglobulins (Igs) ○ 4 looping polypeptides chains ■ Linked together through disulfide bonds ○ Heavy chains ○ Light chains ○ Variable region ○ Constant region ○ Do not destroy antigen; inactivate and tag it for destruction ○ Foram an antigen-antibody (immune) complex ● Antibody Actions ○ Neutralizing antigen. The reaction of antibodies with antigen blocks or neutralizes some bacterial toxins and prevents attachment of some viruses to body cells. ○ Immobilizing bacteria. If antibodies form against antigens on the cilia or flagella of motile bacteria, the antigen–antibody reaction may cause the bacteria to lose their motility, which limits their spread into nearby tissues ○ Agglutinating and precipitating antigen. Because antibodies have two or more sites for binding to antigen, the antigen–antibody reaction may cross-link pathogens to one another, causing agglutination (clumping together) ○ Activating complement. Antigen–antibody complexes initiate the classical pathway of the complement system ○ Enhancing phagocytosis.stem region of an antibody acts as a flag that attracts phagocytes once antigens have bound to the antibody’s variable region. Antibodies enhance the activity of phagocytes by causing agglutination and precipitation, by activating complement, and by coating microbes so that they are more susceptible to phagocytosis ● Immunological Memory ○ Exposure to any antigen ○ Occurs during microbial infection ○ due to the presence of long-lasting antibodies and very long-lived lymphocytes that arise during clonal selection of antigen-stimulated B cells and T cells ○ Primary Response: the amount of antibody in serum. After an initial contact with an antigen, no antibodies are present for a period of several days.Rise in the

Lymphatic System Review antibody titer occurs, first IgM and then IgG, followed by a gradual decline in antibody titer. ○ Secondary Response: ■ more intense response ■ Antibodies produced during a secondary response have an even higher affinity for the antigen than those produced during a primary response, and thus they are more successful in disposing of it. ■ Occurs during microbial infection ● Active and Passive Immunity ○ Active Immunity: production of memory cells due to contact with antigen ■ Naturally acquired: Direct exposure to antigen ■ Artificially acquired: Antigen exposure from vaccine ○ Passive Immunity: No production of memory cells; antibodies from another person or animal ■ Naturally acquired: Transfer is mother to child across the placenta or in breast milk ■ Artificially acquired:Transfer of serum containing antibody from another person or animal ● Thymic Selection ○ Self-recognition: (1) They must be able to recognize your own major histocompatibility complex (MHC) proteins ■ Developed Via Positive selection: cells that can’t recognize self MHC undergo apoptosis ○ Self-Tolerance: (2) they must lack reactivity to peptide fragments from your own proteins ■ Occurs through negative selection: T&B cells that recognize self peptides are eliminated ● Hypersensitivity ○ Abnormal and exaggerated response of immune system to antigens...