The Lymphatic System and Immunity

1. The Lymphatic System and Immunity Lymph fluid (ch.20 Lymphatic) Lymphatic vessels Lymphoid Tissues & Organs

2. Lymphatic and Immune System • Immune response – specific defense • Immunity – ability to resist infection & disease through activation of specific defenses

3. Major Functions • Produce, maintain, distribute lymphocytes • Return fluids and solutes from peripheral tissues of blood • Distribute hormones, nutrients, & waste products from tissues of origin to the general circulation

4. Lymphatic Vessels • Lymph flows along lymphatics with help of valves which respond to pressure from interstitial & capillary volumes • Originate in lymphatic capillaries, end in thoracic duct (body) and right lymphatic duct (right side arm, head & thorax) to circulatory venous system • Fig. 20.1

5. Lymphocytes • Three classes immunocompetent cells protect against antigens -T cells (thymus dependent) Cytotoxic- attack viral infected cells Helper-stimulate T&B cells (regulatory) Suppressor-inhibit T&B cells (regulatory) -B cells (bone marrow-derived) Plasma cells- mature B cells that secrete antibodies (immunoglobulins) in response to a specific antigen (protein generally, lipid, saccharide, nucleic acid) -NK cells (natural-killer) attack cancer cells, viral infected cells, foreign cells

6. Lymphoid Tissues • Lymphoid nodules include tonsils (pharyngeal/adenoids, palatine, lingual), densely packed in loose connective tissue • Peyer’s Patches (in sm.intestines)& Appendix • MALT –bronchi, genitourinary

7. Lymphoid Organs fig.20.5 • Lymph nodes – masses of lymph tissue; filter and purify lymph, efferent & afferent Fig. 20.4 (cortex & medulla) • Thymus – epithelial cells produce thymus hormones; T cell production (cortex & medulla) • Spleen – largest mass of lymphoid tissue; removes abnormal blood through phagocytosis, store iron, initiate immune response by B & T cells

8. Body Defenses (ch.21 Immunity) • 2 general categories -Nonspecific defenses (Innate): do not discriminate, respond the same to all threats -Specific defenses (Adaptive): (occur after birth) discriminatory so only attack specific threats

9. Nonspecific Defenses p. 796 • Physical Barriers • Phagocytes • Immunological Surveillance • Interferons • Complement • Inflammation • Fever

10. Physical Barriers fig. 21.4 • Keeps hazardous material outside body • Skin, keratin, mucus

11. Phagocytes • Cells that engulf pathogens and cell debris • Ex: Macrophages of peripheral tissues, microphages of blood

12. Immunological Surveillance • Destruction of abnormal cells by NK cells in peripheral tissues • NK cells attack quickly, killing tumor-specific antigens as well (cancer cells)

13. Interferons • Chemical messengers coordinate defenses against viral infection

14. Complement • System of circulating proteins that assist antibodies in destruction of pathogens • Activate via classic or alternate pathway • Stimulate inflammation and enhance phagocytosis

15. Inflammation • Local response to injury or infection at tissue level • Restrict injury spread and combat infection • Response to Injury steps 1-8

16. Fever • Elevation in body temperature (via protein pyrogen) to accelerate tissue metabolism and defenses • Ex. Interleukins-1

17. Specific Response • Immune Response Table 21.4 -Forms of Immunity -Properties of Immunity -T cells -B cells -Responses to Antigen Exposure

18. Review of Forms of Immunity • Innate – genetically determined • Active – follows exposure to antigen -Naturally acquired – after birth -Induced active – immunization • Passive – transfer of antibodies -Natural – mother to child -Induced – administer antibodies

19. Properties of Immunity • Specificity – target specific pathogen • Versatility – differentiate among pathogens • Memory – stronger response after 2nd appearance • Tolerance – immune system does not respond to normal pathogen

20. Antibodies • Two parallel pairs of polypeptide chains; bind to antigen • Classes Table 21.3 • IgG—largest • IgE—attach to exposed surfaces • IgD—surfaces of B cells • IgM—first type secreted after antigen arrival • IgA—glandular secretions

21. Antibodies Destroy Antigens • Neutralization—block binding site • Agglutination & precipitation—form large immune complexes • Activate complement • Attract phagocytes • Opsonization—coat proteins for more effectiveness • Stimulate inflammation • Prevent bacterial, viral adhesion

22. Responses to Antigen Exposure • Primary—1st time antigen appears, gradual attack • Secondary—2nd time antigen appears, rapid response via memory cells

23. Hormones of Immune System • Interleukins—enhance defenses, stimulate T and B cell activity • Interferons • TNFs—slow tumor growth • CSFs—stimulate blood cell production

24. Developing Resistance • Immunological competence—ability to demonstrate immune response upon exposure

25. Immune Disorders • Autoimmune disorder—mistakenly targets normal cells • Immunodeficiency—immune system blocked, fails • Allergies—excessive response to antigen (hypersensitivity)

26. AIDS • Caused by HIV • Retrovirus (carries genetic information in RNA, not DNA)

27. Stress and the Immune Response • Depression of inflammatory response • Reduction in phagocyte activity • Inhibition of interleukin secretion

28. Aging and the Immune Response • Less effective at combating disease • Fewer T helper cells • Vaccinations important for vulnerable elderly

29. Integration with Other Systems • Provide IgA for secretion onto skin • Cytokines affect CRH and TRH production • Fight infections of respiratory, circulatory, and digestive organs • Immune system is supplied by other systems equally

30. Questions or Comments? • Works Cited Fundamentals of Anatomy and Physiology (Martini) http://www.mhhe.com/biosci/ap/holehaap/student/olc2/chapterindex16.htm http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookIMMUN.html Du, et al.