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Immunity

Immunity. Body’s defense against invaders. Specific Defenses. Active and Passive Immunity.

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Immunity

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  1. Immunity Body’s defense against invaders

  2. Specific Defenses

  3. Active and Passive Immunity • Active Immunity: 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

  4. Active and Passive Immunity

  5. Humoral Immunity • Antibodies that circulate in the blood • Fight bacteria and viruses (enemy) • B lymphocytes • CELL-MEDIATED IMMUNITY • Fight cellsinfected with germs, also transplants • T lymphocytes

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

  7. 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.

  8. 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

  9. 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

  10. 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, secrete interferon, a chemical that rouses natural killer cells.

  11. Allergy

  12. AIDS • Destroys helper T cells • Body can’t fight pathogens • Death comes from secondary infections

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

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