Docstoc

Blood - Download as PowerPoint

Document Sample
Blood - Download as PowerPoint Powered By Docstoc
					Immunity




           1
    Erythrocytes (Red blood cells)
   Red blood cell (RBC) count is a count of the actual
    number of red blood cells per volume of blood. Both
    increases and decreases can point to abnormal
    conditions.

   Hemoglobin (Hgb) measures the amount of oxygen-
    carrying protein in the blood.

   Hematocrit (Hct) the ratio of packed red blood cells to
    total blood volume. Normal is about 45%


                                                              2
Thalassemia A hereditary form of anemia where
 the RBCs have abnormal hemoglobin that deforms the cells
    into strange shapes (target cells, teardrops, spheres)

                                                 TEAR DROP


  TARGET CELLS


SPHEROCYTE




                                                         3
        Sickle Cell Disease
 A hereditary mutation resulting in one
  valine amino acid substituted for glutamic
  acid.
 Present in African Americans more than
  in other groups, and is always
  characterized by sickled erythrocytes.
 The sickle shape helps prevent malaria
  infections, but it also causes blood clots.

                                                4
            Pernicious anemia
          (megaloblastic anemia)
   Very large erythrocytes, caused by lack of vitamin B12 or
    intrinsic factor
   When a person has gastric bypass surgery, the stomach
    is no longer able to produce intrinsic factor, which is
    needed to absorb vitamin B12, which is needed to make
    hemoglobin in RBC’s.
   Without this vitamin, the blood cells are fewer and much
    larger than normal (megaloblastic).
   The surgery patient must take vitamin B12 shots or
    sublingual supplements for the rest of their life.


                                                            5
                LEUKEMIA
 Cancer of the blood is called leukemia. It
  actually only involves the white blood cells.
 Something goes wrong in one stem cell, and it
  starts making huge amounts of clones of itself
  which don’t work right and not enough normal
  white blood cells are made. Therefore, the body
  cannot fight infection. So, the immature white
  cells are sent into the bloodstream. It’s better to
  send a young cell with no weapons to the war
  than to send nothing at all!
 Think of Leukemia as too few mature
  white blood cells.
 Even though the WBC count is high, they are all
  immature forms.
                                                    6
         Disorders of Platelets

– Thrombocytopenia
   Abnormally low
    concentration of platelets
   Blood does not clot
    properly




                                  7
                Pathogen
    “Path” = disease “ogen” = generating
 A pathogen is something that causes
  disease.
 A biological pathogen is a bacterium,
  virus, fungi, yeast, protozoa, worms, etc.
 A non-biological pathogen can be a toxic
  chemical, asbestos, etc.
 Usually, the term “pathogen” refers to a
  biological pathogen.

                                               8
               Sizes of Pathogens
   Bacteria are so small that hundreds of them can
    fit inside one white blood cell.
       However, bacteria usually do not invade body cells.
        They live between the cells of the body, using up
        nutrients in the area, and they cause harm by
        secreting toxins.
   Viruses are so small that thousands of them can
    fit inside the NUCLEUS of one white blood cell.
       They always try to invade body cells because they
        need a piece of our DNA or RNA in order to replicate.
       When a body cell has been invaded by a virus, the
        entire cell must be killed by a white blood cell.
                                                                9
                Antigen
 An antigen is anything that causes an
  immune response, which isn't necessarily
  a biological pathogen (disease-causing
  organism).
 A non-biological antigen can be pollen,
  dust, grass, or anything that a person is
  allergic to.
 Pollen can be an antigen to a person with
  allergies, but it is not an antigen to a
  person without allergies, because no
  immune response was launched.           10
    LEUKOCYTES (White blood cells)
        all fight infection
   BASOPHILS
    – MAST CELL
 EOSINOPHILS
 NEUTROPHILS
 MONOCYTES
    – MACROPHAGES
   LYMPHOCYTES
    – B CELLS
    – T CELLS

                                     11
                 BASOPHILS
   Basophils – only about
    0.5% of all leukocytes
    – Granules secrete
      histamines (vasodilation;
      more WBCs can get to the
      infection site)
    – Antihistamines interfere
      with the function of
      basophils.
    – Mast Cell: a basophil that
      leaves the blood vessel
      and enters the tissues.
                                   12
                   Eosinophils
   Eosinophils –
    compose 1-4% of all
    WBCs
    – Play roles in:
        Ending allergic
         reactions, parasitic
         infections
        During these conditions
         they increase in
         numbers: eosinophilia
        (too many is ___philia
        too few is ___penia)      13
14
15
                Neutrophils
 Neutrophils – most
  numerous WBC
 First to respond to
  infection
    – Phagocytize and destroy
      bacteria
    – Also destroy bacterial
      toxins in body fluids
    – Nucleus – has two to six
      lobes
                                 16
              Neutrophils
 Neutrophils are the white blood cells that
  contribute to immunity mainly by
  engulfing BACTERIA and foreign bodies
  (thorns, dirt, etc) in a process called
  phagocytosis.
 They release the contents of their
  lysosomes onto the invader, dissolving it.
 When a bacterium has a capsule, it makes
  it hard to phagocytize, so the neutrophil
  requires opsonization by antibodies.
                                           17
             Opsonization
 Some bacteria have evolved a slippery
  capsule around them as a defense against
  phagocytosis. The neutrophil cannot
  engulf this type of bacteria. Neither can a
  macrophage.
 When an antibody attaches to this type of
  bacteria, the neutrophil can now grab onto
  the antibody like a handle, enabling it to
  phagocytize the bacteria.
 This process of facilitation of phagocytosis
  is called opsonization.                    18
 When an invading bacteria has the antibody
  attached to its cell membrane, the entire
  structure is now called an antigen-antibody
  complex.
 If a bacterium does not have a capsule, the
  neutrophil can destroy it without opsonization.
  The antibody can also destroy the bacterium by
  itself by popping the cell membrane.
 But when a capsule is present, the neutrophil
  and antibody work best together.
 Neutrophils are also the ones that
  primarily destroy the dissolved toxins that
  bacteria secrete into body fluids.              19
                     Monocytes
   Comprise about 5% of all WBC’s.
   Like neutrophils, they phagocytize
    (eat) bacteria, old cells, and
    foreign bodies. They have more
    types of lysosome enzymes than
    neutrophils so they are better at
    killing difficult pathogens.
   They also use antibodies for
    opsonization.
   When they leave the
    bloodstream and enter the
    tissues, they are called
    MACROPHAGES.
                                         20
WBC’s leave the blood vessel
   to enter the tissues




                               21
    What’s the Difference between Neutrophils and
              Monocytes/Macrophages?
 There are 10x more neutrophils in the bloodstream than
  monocytes/Macrophages. Consider neutrophils to be
  the most numerous white blood cell.
 However, there are more macrophages in the tissues of
  the body. They are everywhere!
 Neutrophils live only a few days. Monocytes/Macrophages
  live a few months. Lymphocytes live for years.
 Monocytes/Macrophages are larger and slower than
  neutrophils, but they can phagocytize larger organisms
  and more of them.
 Neutrophils usually just phagocytize bacteria until they
  die. Macrophages phagocytize and then take pieces of the
  dead bacteria and present them to lymphocytes so a
  larger immune response can occur.                        22
          Differences in Function
   There are two types of phagocytes: Neutrophils and
    macrophages.
     – Neutrophils and macrophages both mainly function by
       phagocytizing bacteria (not viruses).
   Lymphocytes are mostly needed to kill off body cells
    infected by viruses.




                                                         23
       Differences in Function
 Neutrophils just phagocytize bacteria and secrete
  chemicals to recruit more white blood cells to the
  site.
 Unlike neutrophils, macrophages have surface
  receptors; these "recognize" the surface of the
  pathogen’s cell membrane.
 Macrophages phagocytize the bacteria, pop their
  lysosomes onto it, and dissolve it, except for
  some pieces of the bacteria’s cell membrane.
 The macrophage places these pieces of bacteria
  on its own cell membrane, and finds a
  lymphocyte to present it to.                     24
        Differences in Function
 Macrophages present these pieces to T cell
  lymphocytes and to B cells lymphocytes.
 The lymphocyte feels the shape of the bacteria
  pieces on top of the macrophage, (this is called
  “antigen presentation”) and the lymphocyte can
  then launch an attack on the rest of the bacteria
  still alive in the body.
 In this way, the macrophage recruits even more
  lymphocytes to join the war.
 So, what is a lymphocyte?
                                                  25
                    Lymphocytes
   20–45% of WBCs
    – The most important cells of the
      immune system
    – There are two types of
      lymphocytes; one type is
      effective in fighting infectious
      organisms like body cells
      infected with viruses
    – Both types of lymphocytes act
      against a specific foreign
      molecule (antigen)


                                         26
                 Lymphocytes
       Two main classes of lymphocyte
    –    B cells – Originate in the bone marrow,
         mature into plasma cells. A mature
         plasma cell fights infection by
         producing antibodies
    –    T cells – Originate in the thymus gland.
         They attack foreign cells directly (including
         organ transplants!). They can also kill
         viruses.

                                                     27
                 Lymphocytes
       B cells – mature into plasma cells
       Plasma cells secrete antibodies; the
        plasma cell’s antibodies are what
        kills the attacking cell.
       Antibodies attack in two ways:
    –    They attach to bacteria and pop the cell
         membrane
    –    They attach to encapsulated bacteria to
         help neutrophils and macrophages to
         phagocytize them.
                                                    28
Disorder of B-cell Lymphocytes
       Mononucleosis: Epstein Barr virus
        attacks B lymphocytes. It is
        characterized by inflammation of lymph
        vessels (lymphangitis).
    –     Lymphangitis: lymph vessel inflammation;
          usually from infection.
Infected lymphocytes have a
characteristic scalloped
edge where they touch
RBC’s                                            29
Function of a B Lymphocyte




                                 30
                        Figure 17.6b
           T-cell Lymphocytes
   T cells – coordinate the immune response by
    recruiting other white blood cells.
   They can directly destroy bacteria by popping their cell
    membrane.
   T cells can also directly destroy foreign cells by
    popping the cell membrane.
   They do not need to phagocytize the invading cell.
    They do not need the assistance of antibodies.
   T-cells can therefore kill a body cell that has become
    infected with viruses.



                                                          31
T-Cell




         32
          T-cell Lymphocytes
   T cells are the cells that attack
    organ transplants!
        Immunosuppression drugs are designed to
         inhibit the action of T cells.
        T cells are attacked by the HIV (AIDS)
         virus.
        The thymus gland secrets certain
         hormones which can cause T cells to
         become immunocompetent (makes the
         cells mature and start to work)


                                                   33
                           T Cells
There are several types of T cells. The main types are
 Cytotoxic (Killer) T cells
   – Go out and directly kill bacteria or infected host cells
 Helper T cells
   – Release chemicals called “cytokines” to call in more white blood
      cells of all types to join in the war. They also present the
      macrophage’s antigen to a B cell, which causes it to produce
      antibodies against that particular bacteria. The B cell is now
      called a plasma cell
 Suppressor T cells
   – Stop the immune process when it is over, and also "tell" some
      plasma cells to "remember" how to destroy that specific
      pathogen. Those plasma B-cells are then called Memory B-Cells.
      They can react to the same pathogen faster, the next time it
      invades because Memory B-cells already have the proper
      antibodies stored up for that pathogen.

                                                                   34
Killer T-
  Cell




        35
Virus-Infected Cell




                      36
Function of a T- Lymphocyte




                                  37
                         Figure 17.6a
                      Summary
   A pathogen somehow gets past the body's physical and
    chemical barriers and the inflammation response.
   The pathogen is engulfed by a macrophage (or
    neutrophil).
   The macrophage releases the contents of its lysosomes
    onto the bacterium and dissolves most of it. There are
    still some pieces of the bacterium’s cell membrane left.
    The macrophage then forces the surface proteins of the
    bacterium (antigens) to it's own cell surface.
   Helper T-Cells touch these surface antigens, make a
    copy of their shape, and present them to B-cells to make
    antibodies against them.
                                                           38
                           Summary
   These Helper T-Cells begin to multiply and have two main roles.
   The first is to activate B-Cells and "tell" them how to neutralize the
    pathogen by presenting the pieces of the bacterium cell membrane
    so the B-cells can turn into plasma cells which make the antibodies.
     – The B-Cells (now called Plasma cells because they have been
         activated) begin to multiply and produce the antibodies to
         neutralize this specific pathogen.
   The second role of Helper T-Cells is to activate the Killer T-Cells by
    secreting cytokines.
   Killer T-Cells can either destroy the pathogen itself (bacteria), or
    destroy the entire body cell which is infected (viruses).
   When the immune response is over, Suppressor T-Cells stop the
    process and also "tell" some B-Cells (plasma cells) to "remember"
    how to destroy that specific pathogen.
   Those B-cells (plasma cells) now become Memory B-Cells.                39
                 Antibodies
 Antibodies (also known as immunoglobulins,
  abbreviated Ig) are proteins made by plasma
  cells.
 They are used to identify and neutralize foreign
  objects, such as bacteria and viruses.
 They are typically made of basic structural
  units—each with two large heavy chains and two
  small light chains—to form a unit shaped like the
  letter “Y”

                                                  40
   A Typical
   Antibody
The tips of the “Y”
have receptors that
are specific for a
particular antigen.

The stem of the “Y”
can be grasped by a
phagocyte.



                      41
                  Antibodies
 The small region at the tip of the protein is
  extremely variable, allowing millions of
  antibodies with slightly different tip structures,
  or antigen binding sites, to exist.
 This region is known as the hypervariable
  region. Each of these variants can bind to a
  different target, known as an antigen.
 This huge diversity of antibodies allows the
  immune system to recognize an equally wide
  diversity of antigens.

                                                       42
                     Antibodies
   Some of these “Y” shaped units
    exist by themselves (monomers)
   Some are in pairs (dimers)
   Some are in a cluster of five
    (pentamers)
   There are five different antibody
    types , which perform different
    roles, and help direct the
    appropriate immune response for
    each different type of foreign
    object they encounter.

                                        43
#1   #2                             #3
      Precipitation/agglutination




                                         44
         Types of
        Antibodies

IgD – initiation of immune response

IgE – stimulates allergic reactions, good for
worm infections

IgG – highest concentration in blood, highest
amounts in most secondary responses,
crosses the placenta


IgA – secretory Ig, found in secretions,
highest concentration in body
                                                J-Protein is what attaches the
                                                antibody segments

IgM – produced first, best at C’ activation


                                                                                 45
                   Capsule

                                              Pops
                                             the cell
             Opsonization                                                                      Virus

                                                                           Bacteria
                     Bacteria                   Antibodies

                                   Plasma
                                     Cell                                      Pops the cell
                                                               Cytokines
    Phagocytosis                                                                               STOP




                                                        Presentation



                                                                 Helper          Killer    Suppressor
Neutrophil      Macrophage                  B-Cell
                    (Monocyte                                    T-Cell          T-Cell      T-Cell
                 in bloodstream)

                                                                                                 46
                                                                       Lymphocytes
               IMMUNITY
   Most people are sick more often as
    children than as adults in their 20s
    through 30s because we build up many
    varieties of memory lymphocytes during
    childhood, providing immunity from more
    and more antigens during adulthood.




                                              47
        Myasthenia gravis
 Myasthenia gravis (MG): autoimmune
  disease where antibodies destroy or block
  receptors for acetylcholine, a
  neurotransmitter.
 Causes muscle paralysis.
 First attacks small muscles especially
  those that keep eyes open; will spread to
  diaphragm  death.
 To stave off effects, do thymectomy.
                                              48
                    Aspirin
 One baby aspirin a day can help prevent blood
  clots.
 It blocks the ability of an enzyme called COX
  (cyclo-oxidase) to cleave arachidonic acid into a
  molecule called a prostaglandin.
 Prostaglandins are needed for inflammatory
  reactions and for making clotting factors.
 COX inhibitors, such as aspirin, block pain from
  inflammation, but they also INCREASE blood
  clotting time.
                                                      49
           Hematopoiesis
Fig. 9-1




                           50
Life span, from longest-lived
      to shortest-lived:
 Lymphocytes
 Erythrocytes
 Platelets
 Neutrophils




                            51
                  Terms
 Excess neutrophils: neutrophilia
 Few neutrophils: neutropenia


 Excess platelets: thrombocytophilia
 Few platelets: thrombocytopenia




                                        52
                      WBC Count
   White blood cell (WBC) count is a count of the actual
    number of white blood cells per volume of blood. Both
    increases and decreases can be significant.

   White blood cell differential looks at the types of
    white blood cells present. There are five different types
    of white blood cells, each with its own function in
    protecting us from infection. The differential classifies a
    person's white blood cells into each type: neutrophils
    (also known as segs, PMNs, granulocytes, grans),
    lymphocytes, monocytes, eosinophils, and basophils.

                                                                  53
    BLOOD TYPING: The ABO SYSTEM

 Blood typing is the technique for
  determining which specific protein type is
  present on RBCs.
 Only certain types of blood transfusions
  are safe because the outer membranes of
  the red blood cells carry certain types of
  proteins that another person’s body will
  think is a foreign body and reject it.

                                               54
              BLOOD TYPING
   These proteins are called antigens (something
    that causes an allergic reaction). There are two
    types of blood antigens: Type A and Type B.
   A person with Type A antigens on their blood
    cells have Type A blood.
   A person with Type B antigens have Type B
    blood.
   A person with both types has type AB blood.
   A person with neither antigen has type O blood.

                                                   55
56
              BLOOD TYPING
   If a person with type A blood gets a transfusion
    of type B antigens (from Type B or Type AB, the
    donated blood will clump in masses
    (coagulation), and the person will die.
   The same is true for a type B person getting
    type A or AB blood.
   Type O- blood is called the universal donor,
    because there are no antigens, so that blood
    can be donated to anyone.
   Type AB+ blood is considered the universal
    acceptor, because they can use any other type
    of blood. This blood type is fairly rare.
   The rarest blood type is AB negative.
                                                   57
             RH FACTOR
 There is another term that follows the
  blood type. The term is “positive” or
  “negative”. This refers to the presence of
  another type of protein, called the Rh
  factor. A person with type B blood and
  has the Rh factor is called B positive.
 A person with type B blood and no Rh
  factor is called B negative.

                                               58
                RH FACTOR
   The reason this is so important is that if
    an Rh- mother has an Rh+ fetus in her
    womb (from an Rh+ father), her
    antibodies will attack the red blood cells of
    the fetus because her body detects the Rh
    protein on the baby’s red blood cells and
    thinks they are foreign objects. This is
    called Hemolytic Disease of the Newborn
    (HDN).
                                                59
60
                  HDN
 This can be prevented if the doctor knows
  the mother is Rh- and the father is Rh+,
  because that means the baby has a 50%
  chance of being Rh+ like the father.
 Therefore, anytime a mother is Rh-, even
  if the mother says the father is Rh-, you
  can’t be sure who the father is, so they
  will proceed as though the baby may be
  Rh +.
 They will give her an injection of a
  medicine (Rhogam) that will prevent her
  immune system from attacking the baby.  61
                        Rhogam
   Rhogam is given at 18 weeks into the pregnancy and
    again within 72 hours after giving birth.
   It is usually given within 2 hours after giving birth since
    you can’t trust the patient to return after they leave the
    hospital.
   The first baby is not at risk; during the first birth (or
    miscarriage), the placenta tears away and that’s when
    the baby’s blood cells get into the mother’s bloodstream.
   She then forms antibodies against the Rh factor, which
    are ready to attack the second fetus.
   The baby does not make the Rh factor until about 18
    weeks into the pregnancy.
                                                              62
             IMMUNE SYSTEM
 INFLAMMATORY REACTION: When you get
  stuck by a thorn or have an infected cut, the
  body goes through a series of events called an
  inflammatory reaction.
 Four outward signs:
    –   Redness (erythema or rubor)
    –   Heat (calor)
    –   Swelling (edema)
    –   Pain (dolor)


                                                   63
INFLAMMATORY REACTION
   Redness is caused from the blood vessels dilating to
    allow more blood flow to the area. Within the blood are
    platelets to clot the blood, proteins to repair the
    damage, and macrophages, which are white blood cells
    that eat up the foreign body, bacteria, or the dead cells.
   Heat is caused because of the extra amount of warm
    blood flow to the area.
   Swelling is caused from the plasma that leaks out of
    the swollen blood vessels.
   Pain is caused from the pressure of the extra fluid
    pressing on nerves in the area.


                                                             64
        ADAPTIVE IMMUNITY
   Two types of Adaptive Immunity
    – ACTIVE immunity            – PASSIVE immunity
        Naturally Acquired         Naturally Acquired
        Artificially Acquired      Artificially Acquired


     You can also think
     of it this way




                                                        65
              Active Immunity
   Naturally Acquired
    – The body is naturally exposed to an infectious
      agent and launches an immune reaction
   Artificially Acquired
    – The person is injected with a weakened
      (attenuated) or killed organism, as found in a
      vaccination



                                                   66
         Naturally Acquired
          Active Immunity
 This is when the body is exposed to an
  infectious agent and the body has to work to
  produce antibodies which specifically attack that
  infectious agent.
 The white blood cells secrete these antibodies
  which will continue to circulate sometimes for
  years, ready to attack that type of bacteria and
  cause them to pop like a balloon before the
  body can become sick.


                                                  67
      Naturally Acquired
       Active Immunity
– You catch a cold and eventually get better. You can
  never get the same cold virus twice because you will
  have become immune to it. Your next cold is from a
  different virus. There are hundreds of thousands of
  cold viruses; that’s why there is no cure for the
  common cold.
– Another example is when an unvaccinated child is
  exposed to the measles at school and gets the
  disease, but never gets the disease again.



                                                         68
 However, there are some diseases that you
  don’t want to get, even once, such as polio,
  diphtheria, tetanus, and influenza, because the
  first exposure could kill or disable you.
 For these diseases, we have vaccines which are
  made of those organisms which have been
  altered (attenuated) so that the body recognizes
  them as foreign, but they can’t cause disease.
 That way, if the person is exposed to the real
  organism later, the antibodies are already there
  to kill it off without the body getting sick.

                                                 69
         Artificially Acquired
          Active Immunity
   An example is when a child is vaccinated against
    measles as a baby, so when he gets to school
    and is exposed to the disease, he doesn’t get
    sick.




                                                   70
           Passive Immunity
   Naturally Acquired
    – Example is the passing of antibodies from
      mother to infant in breast milk
   Artificially Acquired
    – Example is when a person receives an
      infusion of antibodies from someone else.




                                                  71
     Active vs. Passive Immunity
 Active immunity is long-lived, and may last
  for years or even a life time.
 Passive immunity is short lived, and may
  last only for a few months.


    NOTE: A vaccination is not the same as
    receiving an anti-toxin or anti-venom
    injection. More on that in Micro class.
                                              72
               ALLERGIES
   From a hypersensitivity to substances such
    as pollen or animal hair that would not
    ordinarily cause a reaction. There are two
    types of allergic responses:
       Immediate
       Delayed


                                             73
   Immediate allergic response
Occurs within seconds of contact with the thing
    causing the allergy.
This is the case with anaphylactic allergies, where
    someone who is allergic to seafood or peanuts
    can actually die within minutes because the
    allergic reaction is so severe the throat swells
    shut and they can’t breathe.
They need an injection immediately of epinephrine
    that will stop the reaction.

                                                   74
75
    Delayed allergic response
Delayed allergic response is when the body’s
   first exposure to the substance will not
   cause a reaction, but all exposures
   afterward will trigger the response.
An example is poison ivy.
You won’t itch the first time you touch it.



                                           76
Common
allergens




            77
       Chemical mediators of allergies
   Preformed
    – histamine - ↑       vascular permeability; smooth muscle
      contraction
    – proteases     – mucous secretion, generation of complement split
                     products


   Newly formed (30-60seconds)
    – leukotrienes - ↑         vascular permeability;
               contraction of pulmonary smooth muscles
    – platelet activating factor –        platelet aggregation;
                                contraction of pulmonary smooth muscles
    – prostaglanin D2 – vasodilation; contraction of smooth muscles
    – cytokines – chemotactic and inflammatory                   78
           Symptoms of allergy
 dependent upon site of allergen exposure
 wheal-and-flare reaction
    – Pruritis (itching), erythema
    – skin
 bronchoconstriction
 mucous secretion
 vasodilation (shock)



                                             79
80
Localized anaphylaxis (atopy)

 reaction limited to the site of allergen
  exposure
 pruritis (itchy) and urticaria (hives)


 allergic rhinitis (hay fever)
 asthma (atopic asthma)
 atopic dermatitis (eczema)
 food allergies
                                             81
                      Allergic asthma
   stimulation of ‘allergy attack’
    – airborne allergens – pollen, dust, insect parts
    – blood borne allergens – viral antigens
    – degranulation of mast cells due to IgE cross-linking
          lower respiratory tract
   symptoms
    –   airway edema
    –   mucous secretion
    –   inflammation
    –   = airway obstruction and damage
 asthmatics are hypersensitive to allergens
~5% of U.S. population

   symptoms can range from somewhat mild to life-
    threatening (<5% severe asthma)
                                                             82
      AUTOIMMUNE DISEASE
   A hereditary problem where the body
    thinks its own tissues are foreign bodies,
    and it constantly tries to kill off its own
    tissues.


      Cats worse than dogs for allergies, http://fxn.ws/O5jueJ




                                                                 83

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:18
posted:9/19/2012
language:English
pages:83