BIO CHP 28

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Author:
blackkballoon
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80261
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BIO CHP 28
Updated:
2011-04-17 23:23:39
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Biology immune system HIV AIDS
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Chapter 28 of the biology textbook about the immune system with special focus on HIV/AIDs
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  1. Antigen
    Any foreign substance that elicts an immune system response

    • Generally proteins or carbs from an invading organism
    • "antibody generator"


    • EXAMPLES:
    • pollen and other allergens,
    • bacteria
    • viruses
    • poison ivy (oil)
    • etc.
  2. Immune Defense Cells


    All different varieties of white blood cells
  3. Immune-System Proteins


    • Proteins can:
    • -Destroy antigens
    • Mark antigens for destruction
    • OR
    • -communication molecules
  4. Types of Immune Defense
    • The immune system has two primary defensive strategies:
    • --Nonspecific defenses: do not discriminate between one invader or the next
    • --Specific defenses: provide protection against particular invaders
  5. Nonspecific Defenses
    • Set of barriers
    • -like skin cells
    • and secretions produced by the barriers

    • EXAMPLE:
    • antimicrobial properties of skin, acid secretions in stomach, sweat, oils, tears, saliva, cilia on lungs

    • mount a coordinate action:
    • the inflammatory response
  6. the Inflammatory response
    • Invovles cells and proteins that kill invaders
    • and substances that increase blood flow and blood vessel permeability near injury site (like histamine)
  7. Specific Defenses Work via Acquired Immunity
    Immunity that results from coming into contact with an antigen

    Passively acquired immunity: from transmission of disease-fighting antibodies produced by another individual

    • Actively acquired immunity: develops from natural or deliberate exposure to an antigen
    • --Can be from getting an immunization shot or by catching a disease (like chicken pox)
  8. Types of Acquired Immunity
  9. Actively Acquired Immunity
    • Two Major Divisions:
    • 1. Antibody-mediated: works by production of proteins called antibodies
    • --Bind to a particular antigen and can be:
    • *Receptors on the surfaces of B cells
    • *Free-standing proteins: secreted by B cells


    2. Cell-mediated immunity: cells destroy body's infected cells
  10. Prepared for an Invasion
  11. Lymphocytes
    • White blood cells
    • ~b-lymphocyte cell (B cell): central to antibody-mediated immunity
    • ~T-lymphocyte (T cell): central to cell-mediated immunity and helps initiate-mediated immunity
    • so, critial in both forms

    • B and T cells found throughout lymphatic system
    • ~vessels captures fludis leaked from bloodstream
    • ~subjects these fluids to scrutiny by immune system cells, then returns them to bloodstream
  12. Antibody-Mediated Immunity
    • Antibodies limit infectious attacks:
    • -binding with antigens keeps antigen from binding with anything else
    • -can bind to invaders in a way that macrophages can bind wiht the invaders and kill them
  13. Antibody-Mediated Immunity
  14. Cell-Mediated Immunity
    • Provides Protection when the body's own cells infected by an invader
    • -viruses and some bacteria can infect the body's cells and remain inside them, so no antibodies can't access


    • Central player: THE T CELL
    • 3 varieties
  15. THE T CELL
    • 3 varieties
    • ~Helper T cells: reognizes viral structures displayed on body cell's surface
    • ~Cytoxic (or killer) T Cell: kills body's own infected cells
    • ~Regulatory T cells: protects body's own tissue from attack
  16. Cell-Mediated Immunity
    • When white blood cells (many kinds) kill cell invaders...
    • -they display protein fragments from them on their cell surfaces
    • -fragments now serve as antigens
    • -any cell that plays does this in an antigen-presenting cell (APC)
  17. T Cells
  18. Overview of Immune System Process
  19. Autoimmune Disorders
    • The immune system can attack the body's own healthy tissues
    • -Mistake body's tissues ("self") for foreign substances ("nonself")

    • EXAMPLES:
    • Rheumatoid arthritis: attack connective tissue
    • multiple sclerosis: attack nerve tissue
    • Type 1 Diabetes: attack insulin-producing pancreas cells
  20. Allergies
    Immune system overreaction to a foreign substance (allergen)

    Causes relase of infectioin-fighting compound histamine

    • Inflammatory response ranges..
    • -from small and harmless (sneezing and sniffling)
    • -to large and life-threatinging (asthma or anaphylatic shock)
  21. Acquired Immune Deficiency Syndrom (AIDS)
    caused by HIV: Human Immunodeficieny Virus

    • VIrus is devastating for several reasons:
    • -Attacks the immune system itself
    • -Invasion leads to a harmful infection rapidly
    • -its genetic material mutates rapidly


    the virus itself changes shape at a rapid rate and can invade the immune system undetected.
  22. HIV attacks helper T cells
    Once inside, virus inserts copy of its own genetic material into T cell's DNA

    • can stay inactive for extended periods of time dieen from immune system.
    • -genes are still replicating with T cell genome

    • Also, can use infected cell's metabolic machinery to make its own proteins and genetic material
    • -that is, make more viruses
    • -which leave cell to go infect others
    • -T cells eventually die
  23. T Cell Importance
    • T cells are central to immunity
    • -under attack from HIV, many die
    • -leaving body vulnerable to other invaders
    • -AIDS diagnosed when lymphocyte count is below 200 per micro liter of blood
    • -AIDS victims don't die of AIDS exactly but from a common infection (cold, flu, etc.)
  24. HIV/AIDS
  25. AIDS Vaccine
    • Very difficult to develop a vaccine to prevent AIDS
    • -would have to prevent infection of all T cells
    • -its constantly changing
    • -perhaps an AIDS vaccine will only slow down replication of HIV
  26. Progression of HIV/AIDS
    • Multiple Stages:
    • Initial infection: rapid viral spread, antibody production, flu-liek symptoms
    • asymptomic phase: # free virus decreases, last few months to several years
    • disease progression: virus increases again, muatates
    • -Eventually patient succumbs to opportunistic infection
  27. Transmission of AIDS
    • •High-risk category
    • –Unprotected
    • sex
    • –Anything
    • involving passage of blood, vaginal fluid, semen
    • –Transmission
    • from mother to child before birth

    • •Intermediate-risk
    • –Protected
    • sex
    • –Mother
    • to child: through breast milk
    • –Blood
    • transfusions & organ transplants before 1987

    • •Low-risk
    • –Sharing
    • razors/toothbrushes
    • –Tatooed/Pierced by
    • un-researched source

    • •Very low/No-risk
    • –Shaking
    • hands, sharing a toilet, sneezed on, being in same room, mosquito transmission
  28. HIV Origins and Evolution
    • •Originated
    • in Sub-Saharan Africa in late 19th/Early 20th
    • Century

    • –Lots
    • of urbanization/colonization going on
    • –Evolved
    • from primate virus: Simian Immunodeficiency Virus (SIV)

    • •Probably
    • from blood exchange while hunting or butchering: “bushmeat”

    • •But
    • SIV does not appear fatal for primates
  29. AIDS is considcered an epidemic
    25+ million deaths between 1981-2005

    • -most in Sub-Saharan African
    • -Asia = 2nd

    • Reasons:
    • - First found in U.S. among intravenous drug uses and gay men who developed rare skin cancer.

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