The Lymphatic System and Immunity

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The Lymphatic System and Immunity

• Lymph fluid (ch.20 Lymphatic)
• Lymphatic vessels
• Lymphoid Tissues Organs

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Lymphatic and Immune System

• Immune response specific defense
• Immunity ability to resist infection disease
  through activation of specific defenses

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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

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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

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Lymphocytes

• Three classes immunocompetent cells protect
  against antigens
• -T cells (thymus dependent)
• Cytotoxic- attack viral infected cells
• Helper-stimulate TB cells (regulatory)
• Suppressor-inhibit TB 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

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Lymphoid Tissues

• Lymphoid nodules include tonsils
  (pharyngeal/adenoids, palatine, lingual), densely
  packed in loose connective tissue
• Peyers Patches (in sm.intestines) Appendix
• MALT bronchi, genitourinary

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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

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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

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Nonspecific Defenses p. 796

• Physical Barriers
• Phagocytes
• Immunological Surveillance
• Interferons
• Complement
• Inflammation
• Fever

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Physical Barriers fig. 21.4

• Keeps hazardous material outside body
• Skin, keratin, mucus

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Phagocytes

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

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Immunological Surveillance

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

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Interferons

• Chemical messengers coordinate defenses against
  viral infection

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Complement

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

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Inflammation

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

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Fever

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

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Specific Response

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

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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

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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

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Antibodies

• Two parallel pairs of polypeptide chains bind to
  antigen
• Classes Table 21.3
• IgGlargest
• IgEattach to exposed surfaces
• IgDsurfaces of B cells
• IgMfirst type secreted after antigen arrival
• IgAglandular secretions

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Antibodies Destroy Antigens

• Neutralizationblock binding site
• Agglutination precipitationform large immune
  complexes
• Activate complement
• Attract phagocytes
• Opsonizationcoat proteins for more effectiveness
• Stimulate inflammation
• Prevent bacterial, viral adhesion

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Responses to Antigen Exposure

• Primary1st time antigen appears, gradual attack
• Secondary2nd time antigen appears, rapid
  response via memory cells

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Hormones of Immune System

• Interleukinsenhance defenses, stimulate T and B
  cell activity
• Interferons
• TNFsslow tumor growth
• CSFsstimulate blood cell production

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Developing Resistance

• Immunological competenceability to demonstrate
  immune response upon exposure

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Immune Disorders

• Autoimmune disordermistakenly targets normal
  cells
• Immunodeficiencyimmune system blocked, fails
• Allergiesexcessive response to antigen
  (hypersensitivity)

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AIDS

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

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Stress and the Immune Response

• Depression of inflammatory response
• Reduction in phagocyte activity
• Inhibition of interleukin secretion

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Aging and the Immune Response

• Less effective at combating disease
• Fewer T helper cells
• Vaccinations important for vulnerable elderly

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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

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Questions or Comments?

• Works Cited
• Fundamentals of Anatomy and Physiology
  (Martini)
• http//www.mhhe.com/biosci/ap/holehaap/student/ol
  c2/chapterindex16.htm
• http//www.emc.maricopa.edu/faculty/farabee/BIOBK
  /BioBookIMMUN.html
• Du, et al.