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					Nonspecific Host Defenses and
       Host Systems
                              Outline
• Intro
• Skin & Mucous Membranes
          – ______Factors
          – _______ Factors
          – Normal Microbiota & Nonspecific Resistance

• Cellular Defenses (Nonspecific Leukocytes, Specific)
          – Formed Elements in Blood
          – Actions of Phagocytic Cells
          – The Mechanism of ______

• Inflammation
          – Vasodilation & Increased Permeability of Blood Vessels
          – Phagocyte Migration & Phagocytosis
          – Tissue Repair

• Fever
• Antimicrobial Substances (Molecular Defense)
          – 1
          – 2
                 Introduction
• Why do we need an immune system?

    •-
         – Examples
             »1
             »2
             »3
            Immunology Terms
• Resistance
     •-
• Susceptibility
     •-
• Nonspecific Defenses (Resistance)
     •-
• Specific Defenses (Resistance)
     •-
3 Lines of Defense protect us
  from microbial invasion
       First Line of Defense
• 1.

• 2.

• 3.
        First Line of Defense
• Both mechanical and chemical factors are
  involved in the first line of defense
          Mechanical Factors
• Skin
     • 1.
     • 2.
     • 3. Bacteria that cause most skin infections
            » Staphyolcocci
           Mechanical Factors
• Mucous membranes
    • 1.
    • 2.
    • 3. Epithelial layer of mucous membrane continuously
      secretes mucus which prevent tracts from drying out and
      can trap microbes in the thick secretions.
           » Eye-lacrimal apparatus (diagram)
           » Mouth-salivary glands
           » Respiratory tract-ciliary escalator (diagram)
            Eye-Lacrimal Apparatus

• The eye has a combination of
  _______and ______factors to
  prevent infection.

• Lacrimal glands continuously
  secrete _______(tears) which
  wash the eye and drain down
  the nose.

• Lacrimal fluid contains
  _______, an antimicrobial
  agent
 Respiratory tract has a ciliary escalator

• ________continuously
  secrete mucus.
• Antigens get stuck in the
  ____.
• Cilia on the epithelial cells
  move the mucus _____ and
  _______
• _________ burn their cilia
  and inhibit the ciliary
  escalator. This predisposes
  them to ________.
                Chemical Factors
• Sebaceous glands
       • sebum forms protective layer, but can be infected -->____
• The following secrete lysozyme, an enzyme that breaks
  down cell walls of gram-positive
       •   1
       •   2
       •   3
       •   4
• Gastric Juice
       • mixture of HCl, enzymes and mucus
       • pH _____ destroys most, however some food borne pathogens invade
         and survive by being protected by food particles
      3. Normal Microbiota
• ___________
    • normal microbiota prevent pathogens from
      colonizing the host by competing with them for
      nutrients, by producing harmful substances, and by
      altering pH and oxygen.

       – Examples
           » normal microbiota in vagina alters pH preventing
             overgrowth of Candida albicans
           » E. coli in large intestine produces bacteriocins that inhibit
             Salmonella.
Amount of Microbial Species
           Elements in Blood
• 1
• 2

• 3 Major Cell Types
      • Erythrocytes (____)
      • Leukocytes (____) *
      • Thrombocytes (_____)
  What is the major function of
         each cell type?
• Erythrocytes?
  –_


• Leukocytes?
  –_


• Thrombocytes?
  –_
        Types of Leukocytes
•   1
•   2
•   3
•   4
•   5
  Which cells are leukocytes?
Which leukocytes are phagocytic?
Where do our blood cells come from?
         Leukocyte Numbers
• During infections, the number of specific cell
  types can change. (original proportion=NLMEB)
• Detected by a Differential WBC count


• Leukocytosis
     • ______in number of leukocytes
            » can occur, especially during bacterial infections

• Leukopenia
     • ______ in number of leukocytes
            » salmonellosis, brucellosis
         Functions of Leukocytes
• Granulocytes
• ______
     • produce histamine, inflammatory and allergic responses

• _______
     •   60-70% of WBCs aka polymorphonuclear leuk (PMNs)
     •   Highly_______and motile
     •   active in _____ stages of infection
     •   ability to ________and destroy microbes

• ________
     • produce toxic proteins against certain parasites;some phagocytosis
     Functions of Leukocytes
• __________
    • not actively phagocytic until they leave circulating blood, enter
      tissue and mature into macrophages

• _________
    • highly phagocytic; remove microbes and worn out cells, particles

• _________
    • not phagocytic, but play a key role in specific immunity B-
      lymphocytes (antibody production)
             » T-lymphocytes (cell-mediated immunity)
                 Phagocytosis
• Ingestion of a microorganism or any particulate
  matter by a cell.

• Phagocytes
     • cells that _________
     • all are ________but only some leukocytes are ______.
       Which ones?
     • activated by components of bacteria, such as lipid A or
       LPS, or other antigens
     • also activated by hormones secreted by other phagocytes
     Actions of Phagocytic Cells
• When infection occurs, granulocytes (mostly
  PMN,neutros) and ______ migrate to the infected area.
• Once a monocyte migrates into the tissue it matures into a
  ________


• Types of Macrophages
       • Wandering
              » _
       • Fixed
              » _
           During an infection
• 1
      • increased PMNs then macrophages start to dominate


• 2
      • macrophages predominate


• Sometimes can perform differential WBC count to
  investigate etiologic agent of disease.
        Mechanism of Phagocytosis
• 1.
          • chemical attraction of phagocytes

• 2.
          • can be inhibited by capsule or M protein

• 3.
          • pseudopods engulf microbe

• 4.
          • phagosome fuses with lysosome (digestive enzymes)

• 5.
•   *Sometimes pathogens have sneaky ways of killing phagocytes or using them to their
    advantage. Some pathogens use phagocytes to replicate or hide from the immune
    system.
Phagocytosis of two bacterial
   cells by a neutrophil.
         The Lymphatic System
• 3 Major Functions:
  – 1. Collects excess fluid from extracellular spaces that
    leak out from capillaries
  – 2. Transports digested fats to the ______
  – 3.*Major player in nonspecific and specific defenses
  – The lymphatic system can be thought of as a series of
    disease barriers. Each lymph node houses
    macrophages and LYMPHOcytes which try to kill
    invaders.
            The Lymphatic System
• Consists of a network
  of :
  – lymph vessels
  – lymph nodes
  – other lymphatic tissue
     •   1
     •   2
     •   3
     •   Gut-associated
         lymphoid tissue
         (GALT)
       Structure of a lymph node.

• Lymph nodes house _____
• Lymph nodes filter out
  foreign material in lymph
  fluid (DISEASE FILTERS)
• maturation and proliferation
  of ______ and ______ causes
  swelling and pain of lymph
  nodes
• Proliferation of microbes can
  also cause pain and swelling
               Inflammation
• A defensive response triggered by damage to the
  body’s tissues.


• Characterized by:
      •   1)
      •   2)
      •   3)
      •   4)
      •   5)
                 Inflammation
• Is actually a beneficial response.

• Functions
     • 1) Try to ___
     • 2) If can’t destroy, __
     • 3) Repair or replace ___
       Stages of Inflammation
• 1. Vasodilation & Increased Permeability of
  Blood Vessels
     • ______________cause #1


• 2. Phagocyte Migration & Phagocytosis
     • _____________cause #2
     • First neutrophils, then macrophages


• 3. Tissue Repair
     • depending on tissue type--skin-yes, cardiac muscle-no

     • What is pus? Dead cells & body fluids
 Steps in the process
of inflammation and
 subsequent healing
 Does the tissue return to its
       normal state?

 How is scar tissue different
  from the original tissue?

What are the advantages and
disadvantages of scar tissue?
                              Fever
• __
• Fever is _____to infection versus inflammation
  which is a ________.
• Fever is also caused by _______
• ________ is the body’s thermostat, 98.6F=37C

• Signs of Fever
       • When you have a chill and are shivering, what is happening to your
         body temperature?
       • vasodilation and sweating-BT is decreasing (infection subsiding)
Mechanism of Fever
             Purpose of Fever

• Up to a certain point, fever is beneficial.
  –   1.
  –   2.
  –   3.
  –   4.
       Antimicrobial Substances
• In addition to previous chemical factors, 2
  additional antimicrobial substances are important.


• 1.
• 2.
           The Complement System
• The complement system
  consists of a group of
  ~20 proteins that activate
  one another (domino
  effect) to destroy
  invading
  microorganisms.

• Complement activation
  can result in cell lysis,
  inflammation, and
  opsonization.
                     Interferons
• ________are antiviral proteins produced in response to
  viral infection.

• There are three types: ___,____,_____

• ______,_______IFNs induce infected cells to produce
  antiviral proteins that prevent viral replication in
  UNINFECTED cells.

• Interferons are host-cell-specific but not virus-specific

• _______IFN activates _______ to kill bacteria.
Alpha and Beta Interferons are produced by infected
cells. The interferons signal UNINFECTED cells to
            produce antiviral proteins.
 A summary
of the body’s
 nonspecific
  defenses.

				
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