Lymphatic system and immunity


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Lymphatic system and immunity

  1. 1. Lymphatic system and immunity Closely associated with cardiovascular because it includes a network of vessels
  2. 2. Lymphatic vessels <ul><li>Capillaries to larger lymphatic vessels to collecting ducts to subclavian veins in chest </li></ul><ul><li>Protein molecules that leak out of capillaries are returned to blood via lymph </li></ul><ul><li>Movement of lymph is controlled by muscular activity; similar to venous flow </li></ul>
  3. 3. Lymph nodes <ul><li>Lymph glands – contain many white blood cells; about 2.5 cm, bean shaped </li></ul><ul><li>Lymph transports bacteria and viruses to lymph nodes where they are attacked </li></ul><ul><li>Centers for lymphocyte production (a WBC), also made in bone marrow </li></ul><ul><li>Swell when actively fighting infection or disease; you may feel them in neck, armpit or groin </li></ul>
  4. 4. Thymus <ul><li>Soft, bilobed, surrounded by connective tissue </li></ul><ul><li>Modifies lymphocytes into killer T-cells </li></ul><ul><li>Secretes thymosin – stimulates maturation of T-cells after they leave the thymus </li></ul>
  5. 5. Spleen <ul><li>Largest lymphatic organ </li></ul><ul><li>Stores blood </li></ul><ul><li>White pulp is in nodules composed mainly of lymphocytes </li></ul><ul><li>Red pulp contains RBCs, plus lymphocytes and macrophages </li></ul><ul><li>Spleen filters blood looking for foreign material which macrophages destroy </li></ul>
  6. 6. Tonsils, adenoids <ul><li>Tonsils – in back of throat (laryngopharynx) </li></ul><ul><li>Adenoids – in nasopharynx </li></ul><ul><li>Both work in a similar manner to spleen </li></ul><ul><li>Can swell from chronic infections and block breathing or swallowing – can be removed </li></ul>
  7. 7. Nonspecific immunity first line of defense <ul><li>Species resistance – humans are naturally immune to many diseases that affect other species because chemical makeup and body temp are different </li></ul><ul><li>Mechanical barriers – skin and mucous membranes keep out invaders by being relatively impenetrable as long as they are intact </li></ul>
  8. 8. Second line of defense <ul><li>Chemical barriers – </li></ul><ul><ul><li>acid and pepsin in stomach tear apart microbes, </li></ul></ul><ul><ul><li>lysozyme in tears is antibacterial </li></ul></ul><ul><ul><li>Interferons stimulate nearby cells to produce virus blocking proteins </li></ul></ul><ul><li>Fever – causes iron needed by bacteria to by hidden in liver and spleen, also increases the activity of phagocytes </li></ul>
  9. 9. 2 nd line cont. <ul><li>Inflammation – redness, swelling, heat and pain </li></ul><ul><ul><li>results from blood vessel dilation </li></ul></ul><ul><ul><li>WBCs are attracted to the site, may form pus </li></ul></ul><ul><ul><li>Fibrin may form a clot, limits spread of pathogens </li></ul></ul><ul><li>Phagocytosis – neutrophils and monocytes engulf and digest foreign particles </li></ul>
  10. 10. Specific defense (Immunity) third line of defense <ul><li>Antigens – large molecules present in cells </li></ul><ul><ul><li>Your body recognizes “self” and anything else is foreign. </li></ul></ul><ul><ul><li>T-cells and B-cells can recognize foreign antigens </li></ul></ul><ul><li>Cell mediated immunity – T-cells attach to foreign cells and produce chemicals that kill or interfere with cell growth </li></ul>
  11. 12. Immunity cont. <ul><li>Antibody mediated (humoral) immunity – B-cells produce antibodies which react in various ways to destroy specific antigens </li></ul><ul><li>Memory cells – produced by both T-cells and B-cells </li></ul><ul><ul><li>Clones of original cells which fought an infection </li></ul></ul><ul><ul><li>Remain dormant until exposed to any antigen they have previously encountered </li></ul></ul><ul><ul><li>Produce a rapid response </li></ul></ul>
  12. 13. Acquired immunity <ul><li>Active immunity – exposure to a pathogen causes the body to form memory cells – long lasting </li></ul><ul><ul><li>Naturally acquired active immunity – results from actually having the disease and fighting it off </li></ul></ul><ul><ul><li>Artificially acquired active immunity – results from vaccines – a weakened or killed form of the pathogen is introduced into the body </li></ul></ul>
  13. 14. Acquired immunity cont. <ul><li>Passive immunity – a person receives antibodies produced by another person -short term protection </li></ul><ul><ul><li>Naturally acquired passive immunity – babies get antibodies from their mothers through the placenta (before birth) and breast milk. </li></ul></ul><ul><ul><li>Artificially acquired passive immunity – a shot of immunoglobulin (antibodies) that can deactivate a pathogen </li></ul></ul>
  14. 15. Allergic reactions <ul><li>Allergies are immune attacks against nonharmful substances </li></ul><ul><ul><li>Delayed reaction – takes up to 48 hours to show up, usually from repeated chemical exposure </li></ul></ul><ul><ul><li>Immediate – happen right away, involve histamine and heparin </li></ul></ul><ul><ul><li>Either could cause anaphylactic shock which can kill </li></ul></ul>
  15. 16. Transplantation and tissue rejection <ul><li>The body recognizes a transplant as foreign and attacks it unless the tissue types are extremely similar. Even then, a person may have to take immunosuppressive drugs for life. </li></ul>
  16. 17. Autoimmunity diseases <ul><li>The immune system fails to recognize cells as “self” and attacks them </li></ul><ul><li>Proteins on a pathogen’s cell surface may resemble those on your own cells </li></ul><ul><li>Examples </li></ul><ul><ul><li>Type I diabetes </li></ul></ul><ul><ul><li>Multiple sclerosis </li></ul></ul><ul><ul><li>Rheumatoid arthritis </li></ul></ul><ul><ul><li>lupus </li></ul></ul>