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IMMUNE SYSTEM

IMMUNE SYSTEM. Dr. L. Rueda CUHS. FIRST SECTION. Animal Defense Mechanisms. Nonspecific Mechanisms. They provide general barriers to infection

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IMMUNE SYSTEM

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  1. IMMUNE SYSTEM Dr. L. Rueda CUHS

  2. FIRST SECTION

  3. Animal Defense Mechanisms

  4. Nonspecific Mechanisms • They provide general barriers to infection • 1. The skin and Mucous Membranes: skin is a physical barrier to microbes helped by oil and sweat with a low pH. Lysozyme is an enzyme that attacks bacterial cell walls present in tears, saliva and mucus. • 2. Phagocytic White Cells and Natural Killer Cells. a. Neutrophils(WBC) are short lived WBC that phagocytize microbes in infected tissue

  5. Macrophages b. Monocytes (WBC) migrate to tissues and develop into macrophages, large, long-lived amoeboid cells that engulf microbes and digest them. Macrophages may migrate through the body or become permanently attached to lungs, liver, lymph nodes or spleen. Some microbes are resistant to them.

  6. c. Eosinophils (WBC) attack larger parasitic invaders with destructive enzymes. d. Natural Killer Cells destroy the body’s infected or aberrant cells by attacking their membranes.

  7. 3. Antimicrobial Proteins a. The complement system is a group of proteins (about 20) that cooperate with other non-specific defense mechanisms, resulting in lysis of microbes or attraction of phagocytes. b. Interferons are proteins produced by virus infected cells that diffuse to neighboring cells stimulating production of proteins that inhibit viral replication by those cells.

  8. The Complement System

  9. 4. The Inflammatory Response • It is characterized by redness, swelling, and heat. • Injured cells release chemical signals: basophils in the blood and mast cells in connective tissue release histamine, which triggers vasodilation and leakiness of the blood vessels. WBC release prostaglandins that promote blood flood to the injured area. • A systematic inflammatory response may cause fever produced by toxins from the microbe or pyrogens from WBC.

  10. Specific Defenses

  11. Active and Passive Immunity • Active Immunity can be acquired when the body produces antibodies and develops immunological memory from either exposure and recovery from an infectious disease, or from vaccination with an inactivated pathogen. • Passive Immunity: antibodies are supplied through the placenta to a fetus, to milk to a nursing infant, or by antibody injection providing temporal immunity

  12. Active and Passive Immunity

  13. Humoral Immunity • It involves the production of antibodies that circulate in the blood and lymph and defend against free bacteria and viruses.

  14. Cell-Mediated Immunity • It involves specialized lymphocytes that react against body cells infected by microbes. They also response against transplants and cancerous cells.

  15. The immune system mounts specific attacks against invaders when lymphocytes recognize antigens (components of foreign molecules) and produce specific proteins called antibodies.

  16. Cells of the Immune System: B cells • B lymphocytes are produced and developed in the stem cells in the bone marrow. • B cells have specific antigen receptors when activated they produce plasma cells. • B cells produce plasma cells that give raise to antibodies.

  17. Antibodies • The “Y” shaped molecule consists of two pairs of polypeptide chains: two identical short chains and two identical long chains. • Both chains have a constant region in the tail of the “Y” and a variable region at the ends of the two arms, the variable region is specific for different antigens

  18. Cells of the Immune System: T Cells • T cells have antigen specific receptors. • They are produced by stem cells in the bone marrow and develop in the thymus. • Helper T cells stimulate humoral and cellular immunity by secreting cytokines. • Cytotoxic T cells kill infected and cancer cells

  19. IMMUNERESPONSE • Microbes attempting to enter the body must first find a chink in the body's external protection. Skin and mucous membranes are also rich in scavenger cells and IgA antibodies. Next, invaders must elude a series of nonspecific defenses-those cells and substances. Many potential infections are cut short when microbes are intercepted by patrolling scavenger cells or disabled by complement or other enzymes or chemicals. Virus-infected cells, for instance, secrete interferon, a chemical that rouses natural killer cells.

  20. Allergy

  21. AIDS

  22. Resources • http://rex.nci.nih.gov/PATIENTS/INFO_TEACHER/bookshelf/NIH_immune/html/imm35.html

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