Immune System

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Siobhan
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133295
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Immune System
Updated:
2012-02-07 13:43:16
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Immune System
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Immune System
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  1. microbes
    • microscopic living organisms. Most that live in animal bodies do not harm them and may be beneficial
  2. Pathogens
    • microbes that cause disease (cholera, chicken pox)
  3. emerging infectious diseases
    • New, more deadly strains of familiar pathogens (HIV, Ebola, SARS)

  4. Nonspecific Defenses


    • Stomach: protein-digesting enzymes and extreme acidity
    • Intestines: contain bacteria that destroy invaders
    • Urinary tract: slight acidity of urine inhibits bacterial growth
    • Vagina: acidic secretions and mucus

    • Tears, urination, diarrhea, and vomiting all help to expel invaders

  5. Innate immune responses fall into three categories:
    • 1) White blood cells (leukocytes): attack and destroy invading cells or the bodys own cells if they have been infected by viruses
    • 2) inflammatory response: recruits leukocytes to the site of a wound and walls off the injured area, isolating the infected tissue from the rest of the body
    • 3) Fever: is produced when microbes start a major infection in the body, which both slows down microbial reproduction and enhances the bodys own fighting abilities (phagocytes)

  6. Three important types of phagocytes are:
    • Macrophages
    • Neutrophils
    • Dendritic cells

  7. 2) inflammatory response
    • causes tissues to become warm, red, swollen, and painful (mast cells release histamine)
    • This defense mechanism has several functions:
    • It attracts phagocytes to infected or injured tissue
    • It promotes blood clotting
    • It initiates protective behavior by causing pain

  8. 3) Fever combats large-scale infections
    • macrophages release pyrogen that raises the thermostats set point
    • increases phagocytic activity and slows bacterial reproduction
    • stimulates cells infected by viruses to produce a protein called interferon (stimulates natural killer cells)

  9. adaptive immune system: It consists of three major components:
    • 1) immune cells
    • 2) tissues and organs
    • 3) secreted proteins

  10. 1) Immune cells
    • Macrophages and dendritic cells (both innate and adaptive immune responses )

    • The key cellular players: B cells and T cells, which arise from stem cells in the bone marrow
    • B cells: complete their development in the bone marrow
    • T cells: migrate from the marrow to the thymus
  11. B cells
    • complete their development in the bone marrow
    • adaptive immune system
  12. T cells
    • migrate from the marrow to the thymus
    • Adaptive Immune System

  13. Adaptive Immune System

    2) Tissues and organs
    • lymphatic system vessels
    • lymph nodes: contain masses of macrophages and specialized white blood cells called lymphocytes
    • Thymus
    • Spleen: that filters blood, exposing it to white blood cells that destroy foreign particles and aged red blood cells
    • Tonsils: contain macrophages and other white blood cells

  14. Adaptive Immune System: Secreted proteins



    • cytokines, that are used for communication between cells
    • complement, assist the immune system in killing invading microbes
    • B cells, produce antibodies that help the immune system recognize invading microbes and destroy them
  15. cytokines
    • Adaptive Immune System
    • 3) Secreted proteins
    • that are used for communication between cells
  16. complement
    • Adaptive Immune System- secreted protiens
    • assist the immune system in killing invading microbes

  17. All adaptive immune responses include the same three steps:
    • Lymphocytes recognize an invading microbe and distinguish the invader from self
    • They launch an attack
    • They retain a memory of the invader that allows them to ward off future infections by the same type of microbe

  18. How Does the Adaptive Immune System Recognize Invaders?
    • Antibodies and T-cell receptors recognize and bind to foreign antigens
    • Antigens: molecules that can provoke an immune response, including the production of antibodies
    • T-cell receptors: only on the surfaces of T cells
    • A T-cell receptor triggers a response in its T cell when the receptor binds an antigen on a cell that has ingested an invading microbe



  19. Antibodies and T-cell receptors are not tailor-made for antigens
    • B and T cells do not design antibodies and T-cell receptors to fit invading antigens
    • Instead, the immune system randomly synthesizes millions of different antibodies and T-cell receptors
    • Antigens almost always encounter antibodies or T-cell receptors that will bind them

  20. The adaptive immune system simultaneously launches two types of attack against microbial invaders:
    • Humoral immunity is provided by B cells and the antibodies that they secrete into the blood that attack pathogens outside the bodys cells

    • Cell-mediated immunity is produced by a type of T cell called the cytotoxic T cell that attacks infected body cells, killing both the cell and any pathogens inside it
  21. Humoral immunity
    • adaptive immune system
    • is provided by B cells and the antibodies that they secrete into the blood that attack pathogens outside the bodys cells
  22. Cell-mediated immunity
    • The adaptive immune system
    • adaptive immune system
    • is provided by B cells and the antibodies that they secrete into the blood that attack pathogens outside the bodys cells

  23. Cell-mediated immunity is produced by cytotoxic T cells
    • The bodys primary defense against cells that are cancerous or that have been infected by viruses
    • Cytotoxic T cells in the blood may bump into an infected body cell that is displaying a viral protein on its surface
    • The cytotoxic T cell receptor will bind to the viral protein and squirt proteins onto the surface of the infected cell, punching holes in the cell and killing it, sparing new body cells a future infection

    • Cancerous cells also display unusual proteins that the cytotoxic T cells recognize as foreign, and are killed as a result
  24. Antibiotics
    • chemicals that help to combat infection
    • The occasional mutant microbe that is resistant to an antibiotic will pass on the genes for resistance to its offspring, which results in many antibiotics becoming ineffective in treating diseases
    • Antibiotics are not effective against viruses
    • Drugs are available that target different stages of the viral cycle of infection, and are used to treat HIV, severe herpes, and in some cases, the flu virus
  25. Vaccinations
    • A vaccine stimulates an immune response by exposing a person to antigens produced by a pathogen
    • Vaccines often consist of weakened or killed microbes, or some of the pathogens antigens
    • an army of memory cells
  26. Allergies
    are immune reactions to harmless substances that are treated as if they were pathogens
  27. autoimmune disease
    • is an immune response against the bodys own molecules
  28. Immune deficiency diseases
    • occur when the body cannot mount an effective immune response
    • Severe combined immune deficiency (SCID), a group of genetic defects in which few or no immune cells are formed
    • Acquired immune deficiency syndrome (AIDS), where a viral infection destroys a formerly functional immune system
  29. Severe combined immune deficiency
    • a group of genetic defects in which few or no immune cells are formed
  30. Acquired immune deficiency syndrome (AIDS
    • where a viral infection destroys a formerly functional immune system


  31. Cancer
    • Natural killer cells and cytotoxic T cells encounter these new proteins, recognize them as non-self antigens, and destroy the cancer cells
    • Some cancer cells do not bear antigens that allow the immune system to recognize them as foreign or, as in leukemia, suppress the immune system
    • Vaccination can prevent some cancers
    • Attempts to eliminate cancer mostly focus on surgery, radiation, and chemotherapy

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