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The Immune System

The Immune System. Widely dispersed system Review of structure and function. bone marrow. located in marrow cavities of bones yellow vs. red marrow hematopoiesis. The Immune System. Review of structure and function. thymus gland. location

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The Immune System

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  1. The Immune System • Widely dispersed system • Review of structure and function • bone marrow • located in marrow cavities of bones • yellow vs. red marrow • hematopoiesis

  2. The Immune System • Review of structure and function • thymus gland • location • consists of lymphocytes and macrophages • “gives” immunocompetence to T lymphocytes via thymosins

  3. The Immune System • Review of structure and function • spleen • location • red vs. white pulp • functions

  4. The Immune System • Review of structure and function • lymph nodes • locations • structure • function

  5. The Immune System • Review of structure and function • tonsils • locations • functions

  6. The Immune System • Review of structure and function • lymphocytes and plasma cells • What is immunity? • origin and immunocompetence • T cells (cancer cells, transplants, bacteria, virus-laden cells) • cytotoxic T cells • helper T cells • suppressor T cells • memory T cells • B cells (viruses, bacteria) • plasma cells • memory B cells

  7. The Immune System • Review of structure and function • lymphocytes and plasma cells • locations • primary immune response • secondary (anamnestic) response

  8. Age-related changes in the immune system • All lymphoid tissues decreases in mass and efficiency with age • Bone marrow • Thymus gland • puberty to 50, lose 90% of mass • loss of size = loss of thymosins • new T cell immunocompetence decreases

  9. Age-related changes in the immune system • B cells • no decline with age • decreased responsiveness to antigens • by 70, 85% reduction in antibody production • B cell changes may be result of decreased helper T cell numbers

  10. Age-related changes in the immune system • Spleen • Lymph nodes • Tonsils • reach maximum size at 12 • palatine tonsils decrease gradually; pharyngeal tonsil (adenoid) atrophies completely • unclear about functional losses

  11. Age-related dysfunctions in the immune system • General decrease in immune responses • decreased immune sensitivity • increased autoimmunity • causes • decrease in precursor cells • decreased differentiation into T- and B-cells • increased suppressor T-cells • increased factors that inhibit immunity (?)

  12. Age-related dysfunctions in the immune system • Age-associated T-lymphocyte defects • T-cell numbers decrease with age • diseases normally held in check by T-cells are allowed to appear • immunosuppressive treatment has same effect

  13. Age-related dysfunctions in the immune system • Acquired immune deficiency syndrome • HIV infects helper T-cells (CD4 cells), ultimately killing them • alters ratio between helper T-cells and suppressor T-cells • normal ratio is 2:1 • at ratio of 1:1 AIDS symptoms begin to appear • at ratio of 0.5:1, full-blown disease • Lymphomas

  14. Take home messages about immunity • decreased lymphoid tissue body-wide • general decline in immunity • decreased T cell number • decreased B cell activity • increased incidences of autoimmune responses

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