1. The Immune System 1.Bone marrow A. Review of structure and function a.Located in marrow cavities of bones b.Yellow vs. red marrow c.Hematopoiesis thymus gland spleen lymph nodes lymphatic vessels bone marrow

2. The Immune System 2.Thymus gland a.Location b.Consists of thymocytes, lymphocytes, and macrophages c.Confers immunocompetence to T cells via thymosins A. Review of structure and function

3. The Immune System 3.Spleen a.Location b.Red vs. white pulp c.Functions A. Review of structure and function

4. The Immune System 4.Lymph nodes A. Review of structure and function a.Locations b.Structure c.Functions LYMPH IN LYMPH OUT capsule trabeculum afferent lymphatics lymphatic nodule with germinal center medullary cords subcapsular sinus

5. The Immune System 5.Tonsils a.Locations b.Functions A. Review of structure and function soft palate palatine tonsils lingual tonsils pharyngeal tonsil palatine tonsil

6. The Immune System 6.Lymphocytes and plasma cells a.What is immunity? b.Origin and immunocompetence c.T cells = cell-mediated immunity i.Cytotoxic T, helper T, suppressor T, memory T cells ii.Fight cancer cells, transplants, bacteria, virus-laden cells A. Review of structure and function d.B cells = antibody-mediated immunity i.Plasma cells, memory B cells ii.Fight viruses and bacteria e.Primary response vs. secondary (anamnestic) response

7. The Immune System 1.All lymphoid tissues decrease in mass and efficiency with age 2.Bone marrow decreases blood cell formation 3.Thymus gland B. Age-related changes a.Puberty to 50, lose 90% of mass, involutes with fat b.Loss of size = loss of thymosins c.New T cell immunocompetence decreases

8. The Immune System 4.B cells B. Age-related changes a.No decline in numbers with age b.Decreased responsiveness to antigens c.By 70, 85% reduction in antibody production d.B cell changes may be the result of decreased helper T cell numbers 5.Spleen 6.Lymph nodes 7.Tonsils

9. The Circulatory System 1.General decrease in immune responses C.Age-related dysfunctions a.Decreased immune sensitivity to antigens b.Increased autoimmunity c.Causes i.Decrease in precursor cells (bone marrow ?) ii.Decreased differentiation into T- and B-cells iii.Increased ratio of suppressor T cells iv.Increased factors that inhibit immunity (?)

10. The Circulatory System 2.Age-associated T-cell defects C.Age-related dysfunctions a.T cell numbers decrease with age b.Diseases normally held in check by T cells are allowed to appear c.Immunosuppressive treatment has the same effect 3.Lymphomas

11. The Circulatory System a.Human immunodifficiency virus (HIV) infects helper T cells (CD4) cells, ultimately killing them b.This alters the ratio between helper T cells and suppressor T cells c.Normal ratio is 2:1 d.At ratio 1:1, AIDS symptoms begin to appear e.At ration 0.5:1, full-blown disease in progress 3.Acquired immune deficiency syndrome (AIDS) C.Age-related dysfunctions

12. end The Immune System D.Take home messages 1.Decreased lymphoid tissue body wide 2.General decline in immunity 3.Decreased T cell numbers 4.Decreased B cell activity 5.Increased incidences of autoimmune responses