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