Immune system


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My Power Point Presentation on the Immune/Lymphatic Systems. The damn animations and emphasis' better work I have spent more time with them than adding the content.

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Immune system

  1. 1. WORKING TOGETHER The Lymphatic and Immune Systems
  2. 2. WHY DO WE NEED AN IMMUNE SYSTEM? Yes, they do. But: they are non-specific defenses.
  3. 3. REVIEW OF KEY TERMS  Antigen  Antibody  Primary Reaction  Secondary Reaction  Macrophage
  4. 4. WE NEED SPECIFIC DEFENSES TOO. B cells and T cells accomplish this. B cells are important for antibody induced immunity in body fluids T cells are important for cell based immunity. (Think abnormal cells and pathogens in cells)
  5. 5. FIRST LET’S REVIEW NON-SPECIFIC DEFENSES:  Integumentary system  Phagocytes in blood and tissues  Complement  Fever and Inflammation But it is not enough!
  6. 6. 3 CELL TYPES OF THE IMMUNE SYSTEM Lymphocytes “The militia” Phagocytes “The janitors” NK cells “The ninjas”
  7. 7. PHAGOCYTES First line of defense, often attack and remove microorganisms before lymphocytes (T cells and B cells) detect them. 2 Types Microphages – patrol blood Macrophages – patrol peripheral tissue
  8. 8. SPECIFIC DEFENSE CELL 1: T CELLS Thymus dependent cells, recognize antigens when bound to special proteins in a cell membrane, called MHC proteins. 4 Types of T cells  Cytotoxic- highly mobile, seek out and destroy abnormal or infected cells “think detective”  Helper- activate B cells so they are able to produce antibodies “think keys”  Suppressor- Keep the immune system from overreacting “think bouncer”  Memory- on 2nd exposure automatically transform to cytotoxic T cells.
  9. 9. SPECIFIC DEFENSE CELL 2: B CELLS 2 types of B cells B cells - Bone marrow derived cells, each carries its own specific antibody molecule that fits a corresponding antigen. Needs the Helper T cells to activate and stimulate their division. They will eventually divide into plasma cells and Memory B cells. B memory cells – on second exposure they divide into plasma cells that secrete antibodies in massive quantities*. *How massive? -When stimulated by cytokines from a T cell, plasma cells can secrete up to 100 million antibody molecules an HOUR
  10. 10. T CELL ACTIVATION When a macrophage (“think pac-man”) engulfs a pathogen with an antigen on it, the antigens are presented to the T-cell by placing them on its cell membrane at the MHC. The T-cell then is able to recognize and bind to the antigen there and begin dividing.
  11. 11. B CELL ACTIVATION On their surface B cells have specific antibodies that bind with specific antigens.  B cells engulf the antigen and present it on their cell membrane to be recognized by an activated Helper T cell, which gives the B cell the “go ahead”.   The T-cell attaches to the part of the B cell membrane where the antigen is and begins to secrete cytokines to activate the B cell.  The B cell can now divide, accelerate plasma cell formation, and enhance antibody production.
  12. 12. REMEMBER THE DIFFERENCE! Primary Response Secondary Response - Antibodies do not peak until 1-2 weeks after exposure - Even low antigen concentrations will immediately trigger memory B cell response. - IgM are first to appear, but do not create memory cells. Immediate, but limited defense - Antibodies increase rapidly and reach much higher concentrations than with the primary response - IgG rises more slowly and creates memory cells. Takes over response. - Invading organism is often destroyed before symptoms appear.
  13. 13. TYPES OF ANTIBODIES  IgA – Found in secretions of the body.  IgD – Found on the cell membrane of B cells.    IgE – Found wherever IgA is. Thought to be involved in triggering allergic reactions. IgG – Primarily recognizes bacteria, viruses, and toxins. IgM – a very large antibody that binds to food and incompatible blood cells.
  14. 14. HOW ANTIBODIES ATTACK ANTIGENS Phagocyte recognition and destruction Antigens clump together and are targeted by macrophages The toxic portion of the antigen is covered Activate complement proteins that form holes in antigen
  15. 15. SO, HOW DOES THE LYMPHATIC SYSTEM FIT INTO ALL OF THIS? It’s primary function is the production, maintenance, and distribution of lymphocytes! Remember, those are the T cells and B cells essential for specific immunity.
  16. 16. ORGANS OF THE LYMPHATIC SYSTEM The organs of the Lymphatic System include: Lymph Lymphatic Vessels Lymphoid Tissues Lymphoid Organs Lymphocytes
  17. 17. HOW DOES THE LYMPHATIC SYSTEM WORK? More fluid is delivered to tissues than can be carried away.  The Lymphatic System’s circulatory network returns this fluid to the blood stream.  On the way to the major collecting ducts, pathogens are filtered at stops such as the spleen and lymph nodes  Lymphocytes, produced in the organs of the lymphatic system, freely flow through this circuit and patrol. 
  18. 18. FORMATION OF LYMPHOCYTES    Two different types are produced in the bone marrow One type stays there, the other migrates to the thymus to mature, separated from the blood. When they have completed maturing they return to the bone marrow and lymphoid tissues and organs, such as the spleen.
  19. 19. LYMPHOID ORGANS All lymphoid organs are separated from the surrounding tissues by a fibrous connective tissue capsule. Lymph Nodes Thymus Spleen
  20. 20. WHAT IS LYMPH? A thin, watery fluid originating in organs and tissues of the body. It circulates through the lymphatic vessels and is filtered by the lymph nodes. It enters the blood stream at the junction of the internal jugular and subclavian veins.
  21. 21. FLOW OF LYMPH Lymphatic capillaries Small Lymphatic Vessels Superficial and Deep Lymphatics Lymph Nodes Major Lymph Collecting Ducts
  22. 22. THE FILTERING PROCESS  Lymph nodes – Purify lymph before it returns to the venous circulation. 99% of the antigens are removed. A T cell may spend 20 hours in a lymph node. A B cell may spend 30 hours in a lymph node.
  23. 23. OTHER ORGANS OF THE LYMPHATIC SYSTEM   Thymus – the thymus provides a place for lymphocytes to mature, separated from the systemic circulation. The thymus also produces several hormones that are important to the development and maintenance of a normal immune system.
  24. 24. OTHER ORGANS OF THE LYMPHATIC SYSTEM  Spleen – Has the largest collection of lymphoid tissue in the body and does for blood what lymph nodes do for lymph. -removal of abnormal blood cells and components -storage of iron from recycled red blood cells -initiation of immune response by B and T cells in response to circulating antigens.
  25. 25. DISEASES OF IMMUNITY HIV Human Immunodeficiency Virus
  26. 26. PATHOLOGY OF HIV Depletes Helper T cells Circulating antibodies also decrease, and cell mediated immunity is reduced. (As a result pathogens that are usually harmless create opportunistic infections.) The surplus in suppressor T cells as Helper T cells die turns off the normal immune response. Immune surveillance is also decreased, increasing cancer risk.
  27. 27. STAGES OF HIV Acute Infection Clinical Latency AIDS Large amounts of the virus are being reproduced in the body. HIV reproduces at low levels, but is still active Helper T cell count falls to dangerously low levels Usually occurs within 2-4 weeks of infection It is still possible to transmit the virus After rapid Helper T cell destruction, immune system kicks in and body returns to a viral set point. This period may last 8 years or longer. At this stage the immune system is badly damaged and opportunistic infections are likely. Survival is typically 3 years with AIDS. It is only 1 year with an opportunistic infection.
  28. 28. SURPRISING HIV FACTS Virus enters the body under clever camouflage, cloaked in sugar molecules.  There are different strains of the virus, some more deadly than others.  34 million people are living with HIV today.  Transmission to a fetus from the mother is now considered entirely avoidable with medication.  A quarter of AIDS deaths are from TB 