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PowerPoint Presentation - Immune System Notes

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Title: PowerPoint Presentation - Immune System Notes Author: slovelady Last modified by: s lovelady Created Date: 2/16/1998 10:32:21 AM Document presentation format – PowerPoint PPT presentation

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Title: PowerPoint Presentation - Immune System Notes


1
Immune System Notes
2
I. Critical Vocabulary
A. Immune System a set of glands, tissues,
cells, and dissolved proteins that combine to
defend against non-self entities B. Antigen
any non-self chemical that triggers an immune
system response. Antigens are often naturally
occurring molecules (protein, glycoprotein, or
polysaccharide) on the surface of cells and
viruses C. Pathogen any antigen that causes a
disruption in homeostasis - a.k.a. normal,
disease free, functions D. Antibody a protein
produced specifically in response to the presence
of an antigen - neutralizes antigen by bonding to
the antigen E. White Blood Cells (wbcs) a set
of cells called lymphocytes, that free-float in
the blood and lymph fluid - active in the immune
system
3
(No Transcript)
4
III. Non-Specific Response (first line of defense)
  • The Skin
  • 1. pH 3-5
  • 2. normal bacterial flora
  • B. Mucous Membranes
  • ex respiratory and digestive tracts
  • C. Specialized phagocytic white blood cells
    (wbcs) that perform phagocytosis cell eating
  • ex Macrophages large amoeboid cells, that
    consume non-self cellular or non-cellular
    material
  • Antimicrobial Protein
  • ex complement proteins cell lysing activity

5
  • Inflammatory Response
  • 1. vasodialation blood vessels become more
    permeable
  • 2. complement proteins attract phagocytes
  • 3. macrophages consume pathogens and related
    debris
  • 4. high fever triggered by chemicals released by
    wbcs

6
IV. Cell Surface Molecular Markers
A. Major Histocompatibility Complex
(MHC) 1. recognition mechanism a. distinguish
self from non-self 2. set of 20 genes w/100
alleles for each gene 3. MHC genes code for
glycoproteins embedded in the plasma membrane
a. cells use to detect the immediate
environment 4. virtually impossible for two
individuals to have the matching set of MHC
markers, except identical twins 5. two classes
of MHC molecules a. class I MHC all nucleated
cells b. class II MHC lymphocytes
(macrophages, B and T cells)
7
V. Humoral Response (specific)
  • A. Specificity
  • ex produces antibodies in response to non-self
    entities such as toxins, free bacteria and
    viruses
  • Cells Involved (lymphocytes - active form called
    effector cells)
  • 1. B-cells
  • a. originate and mature in bone marrow
  • b. activated B-cells become plasma cells and
    secrete antibodies ? the point of the
    humoral response!
  • c. humoral response only
  • 2. T-cells
  • a. originate in bone marrow - mature in the
    Thymus gland
  • b. of the three types, only helper (TH) T-cells
    participate in the humoral response

8
  • C. Activation of B-cells (two types of
    activation)
  • 1. Clonal selection
  • a. B-cells directly stimulated to secrete
    antibodies
  • b. large number of different B-cells
  • 1. pre-determined during embryonic development
  • c. antigen receptors (in the form of
    antibodies) on the surface of B-cells bind to
    free-floating antigens
  • 1. based on antigen-receptor specificity
  • d. once the antigen is bound to the receptor,
    the B-cell is stimulated to clone itself
    (millions of times over)
  • activated immune system cells are called
    effector cells
  • 1. first type of clone plasma cells secrete
    antibodies
  • 2. second type of clone memory B-cells
    (details later)
  • e. antibodies secreted into the blood and lymph
    bind to the original antigen tagging the
    antigen for consumption by a phagocyte

9
Clonal Selection Figure 43.6 Pg. 905
special note the captions in the textbook for
this graphic are important to review
10
Clonal Selection
click here for video animation
11
2. T-dependent a. antigen binds to specific
antigen-receptor on a macrophage 1. t-dependent
antigen (cannot directly stimulate
B-cells) b. involves macrophages and TH
cells c. macrophage consumes the pathogen
1. in the dermis and in mucous membranes the most
prevalent macrophage is a dendritic
cell d. antigen fragments bind to MHC II
proteins and are presented on the surface of
the macrophage e. CD4 receptors on TH cell bind
to antigen/MHC II complex f. Th are activated,
become effector cells and form clones g. activat
ed TH secrete cytokines which stimulate
B-cells h. effector B-cells form clones
antibody secreting plasma cells i. most
antigens are T-dependent
12
Fig 43.13 - pg. 911 B-Cell Activation Due to
T-Cell Dependent antigen
special note the captions in the textbook for
this graphic are important to review
13
VI. Molecular Basis of Antigen-Antibody
Specificity
  • Antibodies do not generally recognize antigens as
    a whole
  • 1. epitope small, specific regions of the
    antigens structure that fit into the
    antigen-binding site of the antibody
  • A given antigen may have multiple epitopes on its
    surface
  • ? multiple antibodies may bind to the same
    antigen
  • Antibodies are proteins called immunoglobulins
    (Igs)
  • 1. Y-shaped w/4 polypeptide chains
  • 2. do not directly destroy pathogens
  • 3. antibodies block viral attachment site, or
    bacterial toxin
  • 4. antigen-antibody complex tags pathogen for
    destruction by a macrophage

14
Humoral and Antibody-Antigen Graphics
Fig. 43.14
Fig. 43.15
click here for video
Fig. 43.16
15
VII. Cell Mediated Response (specific)
  • A. Specificity
  • 1. produces cytotoxic T-cells (TC) which attack
    and destroy infected cells and cancer cells
  • a. many pathogens, including ALL viruses, are
    obligate intracellular parasites
  • Activation of TC cells
  • 1. intracellular parasites are consumed by
    macrophage
  • 2. MHC II-Antigen complex is recognized by CD4
    TH cell
  • 3. TH cell secretes a cytokine called
    Interleukin-2 which activates TC and B- cells

Fig. 43.11
16
C. Active TC cells (effector cell - following
stimulation by Interl-2) 1. effector TC cells
are called CD8 cells - named for the CD8 protein
associated with the T-cell receptor
protein 2. infected host cells present
pathogenic antigens embedded in a MHC I protein
on its surface (recall all nucleated cells
have) 3. T-cell receptor binds with MHC
I-Antigen complex with help from the CD8
protein 4. TC cell secretes the protein perforin
which lyses the infected cell -or- the cancer
cell 5. effector TC can bind to and destroy
multiple cells.
Fig. 43.12(a)
17
A cytotoxic T-cell (Tc) that has already lysed a
cancer cell
Figure 43.12
18
VIII. Secondary Immune Response/Memory
  • A. Result of exposure to previously encountered
    antigen
  • 1. 3-5 day response time vs. 5-10 day primary
    response
  • 2. immunity lasts longer
  • 3. antibodies produced are more effective
  • B. Performed by memory cells
  • 1. produced during 1 response
  • 2. not active during 1 response
  • 3. activated by the original antigen
  • 4. when activated - rapid proliferation to form
    newly cloned effector cells and, in some cases,
    more memory cells.

19
Fig. 43.7 Immunological Memory
20
IX. Suppressor T cells (TS)
  • A. Function to suppress the immune system when
    the antigen in question is no longer present
  • B. TS are not well understood.
  • C. May be effective in stopping a immune response
    through hormonal secretions.

21
X. Acquired Immunity
  • Active Acquired Immunity
  • 1. dependent on persons own immune system
  • 2. based on non-disease causing antigens that
    stimulate an immune response
  • 3. acquired via vaccines or blood transfusions
    (rare)
  • B. Passive Acquired Immunity
  • 1. transferred from one person to another
  • a. mother to fetus
  • b. mother to baby via mothers milk

22
Fig. 43.10 Summary of the Immune Responses
23
The End
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