1. BIOLOGY OF HUMAN AGING CHAPTER 10 The Immune System

2. Review of Structure and Function Bone Marrow Thymus Spleen Lymph nodes Tonsils

3. Lymphatic and Immune System Functions: u Defends against infection: bacteria, fungi, viruses, etc. u Destruction of cancer and foreign cells. u Synthesis of antibodies and other immune molecules. u Synthesis of white blood cells.

4. Lymphatic System

5. Third Line of Defense: The Immune Response (Specific Immunity) Immunity: “Free from burden”. Ability of an organism to recognize and defend itself against specific pathogens or antigens. Immune Response: Involves production of antibodies and generation of specialized lymphocytes against specific antigens. Antigen: Molecules from a pathogen or foreign organism that provoke a specific immune response.

6. The Immune Response Destroys Specific Invaders Antigen: Molecule that elicits an immune response. “Antibody generating”. u Microbial antigens: Viral capsid, bacterial call wall, etc. u Nonmicrobial antigens: Pollen, latex, food, etc. Antibody: Protein found in blood plasma that attaches to antigen and helps counteract its effects. Vaccination or Immunization: Process in which harmless forms of antigen or pathogen are introduced into body to provoke an immune response.

7. Lymphocytes Mount a Dual Defense 1. Cell Mediated Immunity u Immunity that requires cell to cell contact. u Carried out by T cells: u Develop in the thymus. u T cytotoxic cells: Important in defense against: F Cancer cells F Self cells infected with fungi, viruses, protozoans, and bacteria. u T helper cells: Play a central role in immunity. Act indirectly by controlling the immune functions of other cells: F Increased antibody production by B cells. F Increased phagocytosis by macrophages. F Increased killing of foreign and cancer cells.

8. Development of T and B Lymphocytes

9. T helper cells play a central role in immunity

10. Lymphocytes Mount a Dual Defense 2. Humoral (Antibody Mediated) Immunity u Antibodies are found in our body fluids: F Blood F Lymph F Interstitial fluid u Antibodies are produced by B cells. F B cells develop in bone marrow. u Antibodies are specific molecules that circulate through out our body and attach to foreign antigens, marking them for destruction. u Foreign antigen does not have to be associated with a self antigen to be recognized.

12. Age-related changes Bone Marrow reduction of active red bone marrow Thymus degeneration and reduction of size with aging lesser amounts of thymosins hormone produced (thought to be responsible for the T cells differentiation) Decrease in activity and numbers in Helper T cells Spleen The average weight decreases. (animal studies!) Lymph Nodes Lymph Nodes lymphoid tissue gradually diminishes after puberty. The nodes of older individual contain more macrophages. Tonsils Tend to decrease in size with age (palatine/pharyngeal tonsils).

13. Age-related Dysfunctions n General decrease in Immune Responses n Age-Associated T-Lymphocyte Defects n Acquired Immune Deficiency Syndrome n Lymphomas