Bio 004, College of the Desert

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Bio 004, College of the Desert
2011-07-22 00:27:27
Chapter24 COD Bio4 Body defenses

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  1. First Line of Defense
    External barriers
  2. Physical barriers
    Skin, mucous membranes (cilia & mucus).

    Function: Prevent infection

  3. Chemical barriers:
    • a) Sweat, saliva, tears – antimicrobials.
    • b) Glands (oil, acid).
    • c) Stomach (acid).
    • d) Urinary tract (urine flushing).
    • e) Function: Prevent infection.
  4. Second Line of Defense
    Internal barriers
  5. Physical barriers
    • a) White blood cells (WBC’s).
    • b) Function: Circulate through blood-stream & interstitial fluid, destroying foreign invaders, infected body cells, and dead cell debris.
    • c) Phagocytic WBC’s (macrophages) engulf bacteria, viruses in infected tissue.
    • d) Natural Killer (NK) cells attack virus infected cells and cancer cells.
  6. Interferon
    • For infected cells.

    • 1. Release interferons

    • 2. Interferons attach to cell membrane of healthy cells.

    • 3. Healthy cells produce proteins that inhibit viral re-production.

  7. Chemical barriers Function

    Proteins produced by virus-infected cells help healthy cells resist viruses.

  8. Complement proteins Function

    Circulating proteins that coat surfaces of microbes, making them easier for macrophages to engulf.

  9. Inflammatory Response

    Coordinated set of nonspecific defenses when tissue be-comes damaged.

  10. Histamine

    Released by injured cells causing blood vessels to dilate during inflammatory response.

  11. Prostaglandins

    Increase blood flow to area, causing wound to turn red & warm.

  12. Pyrogens
    Stimulate fever discouraging bacterial growth.
  13. Lymph nodes
    • Play role in body’s immune system by attacking viruses, bacteria.
    • a) Lymph nodes harbor WBC’s which multiply during infection.
  14. Immune System

    Large collection of cells that work together to present a specific response to infection. Total of two trillion immune cells in blood-stream and lymphatic system.

  15. Antigen
    • Foreign substance in the body that elicits an immune response.

    • Usually presented as molecules on the surface of bacteria, viruses, etc.

  16. Antibody

    Protein found in blood plasma that attaches to a particular kind of anti-gen in order to counter its effects. Specific response against a specific antigen.

  17. Immunity
    • Resistance to specific invaders.

    • a) Acquired by natural infection
  18. Vaccination
    • Introduction of the immune system to a vaccine containing a harmless variant of an infectious agent.

    • a) Acquired by unnatural infection
  19. Active immunity
    • Body is actively stimulated to produce antibodies in its own defense.

    • a) Acquired by natural infection/ vaccination
  20. Passive immunity
    • Antibodies are acquired pre-made.

    • a) Acquired by fetus from mother or anti-venin (in case of snakebites).

    • b) Temporary – no antigen stimulation
  21. Lymphocytes
    • WBC’s most often found in the lymphatic system which produce the immune response.
    • 1. Originate in bone marrow (B-cells).
    • 2. Some travel to the thymus (T-cells).

  22. Humoral Immune Response
    • B-cells secrete antibodies against bacteria and viruses present in body fluids .
    • B-cells are carried in the lymph and blood to the sites of infection.
  23. Cell-mediated Immune Response
    T-cells work against infections caused by fungi and protozoans and protect against cancer. Circulate in the lymph and blood, stimulating phagocytosis and B-cells to produce Ab’s.
  24. Antibodies
    • Recognize and bind to specific antigens to help counter their effect.

    • 1. Antigen-binding site and antigen have complementary sites.

    • 2. Great diversity of shapes can recognize and bind to almost every antigen.

    • 3. Mark invaders by forming antigen-antibody complexes which:

    • a) Physically block antigens making them harmless.

    • b) Turn them into large clumps, easily captured by phagocytic WBC’s.

  25. Clonal selection
    • Production of a line of genetically identical cells (clones) that recognize and attack specific antigens that stimulated their production.
    • 1. Capability due to immune system’s specificity and memory of antigens.
  26. Primary immune response
    • First exposure of lymphocytes to antigen - takes several days to produce clonal immune cells.

    • Antibodies reach their peak about 2 weeks after exposure, then decline.

    • Effector cell’s lifespan = 4 – 5 days

  27. Memory cells
    Lymphocytes that can persist for decades in lymph nodes, ready for activation by potential second exposure to an antigen.
  28. Secondary immune response
    • Second exposure of lymphocytes to antigen initiates a faster and stronger response.

    • Activated memory cells multiply quickly producing a large, new clone of lymphocytes.

    • Antibodies are more effective, sometimes offering lifetime immunity.

  29. T-Cells
    • Respond to pathogens already in body cells (cell–mediated response).

    • 1. Two kinds of T cells:

    • a) Helper T-cells.

    • b) Cytotoxic T-cells

  30. Helper T-Cells
    • a) Bind to white blood cells with antigen.

    • b) Identify targets by binding complexes.

    • c) Grow and divide producing more cells and memory cells.

    • d) Activate humoral immune response
  31. Cytotoxic T-Cells
    • a) Actually kill other body cells.

    • b) Identify targets by binding complexes.

  32. Allergies
    • Abnormal sensitivities to antigens in the environment.

    • 1. Antigens = allergens.

    • 2. Allergic reactions happen very quickly to a relatively small amount of allergens.

    • 3. Anaphylactic shock: Especially dangerous type of allergic reaction resulting in a sud-den release of inflammatory chemicals.

    • Blood vessels dilate causing fatal drop in blood pressure → shock. Can be countered with epinephrine

  33. Anaphylactic shock
    • Especially dangerous type of allergic reaction resulting in a sud-den release of inflammatory chemicals.

    • Blood vessels dilate causing fatal drop in blood pressure → shock.

    • Can be countered with epinephrine
  34. Immunodeficiency Diseases
    Conditions in which an individual lacks one or more components of the immune system. Results in susceptibility to infections that are normally not problematic. Severe Combined Immunodeficiency (SCID).
  35. AIDS
    Destroys immune system (helper T-cells), leaving body defenseless a ainst infections. Death occurs from infectious agents or cancer, usually not AIDS directly. Acquired Immunodeficiency Syndrome.
  36. Major Histocompatibility Complex
    Family of genes that encode a large set of cell-surface proteins that function in antigen presentation. Can trigger T-cell responses.
  37. Autoimmune Diseases

    Immune system turns against own body’s cells. Rheumatoid arthritis, Diabetes mellitus (type 1), Endometriosis, Lupus, Multiple sclerosis.