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The immune system
Andrea Duncan
Non-specific defenses
(innate)
Physical barriers
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Skin and mucous membranes
Bark
Biochemical barriers
Stomach
Saliva, sweat, tears
Fever
inflammation
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Phagocytes: Consume foreign or aged materials in
bloodstream and lymphatic system
Leukocyte (white blood cell)—natural killer cell, kills
virus-infected cells
Specific defenses
(adaptive)
Components of blood
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erythrocytes (red blood cells)
leukocytes (white blood cells)
platelets
Leukocytes
Granulocytes
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Eosinophils—focus on parasites of the skin and lungs
Neutrophils—Most common leukocyte, short-lived,
respond to inflammation in an injury (chemotaxis),
macrophagial and cytotoxic to foreign bodies
Basophils—cause inflammation and produce histamine
Monocytes—turn into specified macrophages, ingest
dead neutrophils
Leukocytes continued
Lymphocytes
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Develop in primary lymphoid organs and live in secondary
lymphoid organs (lymph nodes, spleen, appendix, tonsils,
intestinal tract, under skin)
Bone marrow—produces stem cells, which differentiate
into different types of blood cells
Travel through both blood and lymphatic systems, pass
from blood through lymph nodes, pass from lymphatic
system through thoracic duct
Two types
B cells
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Produced and Develop in bone marrow
Antibody-mediated immune response
Produce antibodies (protein) when they encounter an
antigen
B cell Antibodies
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Each B-cell is covered with the same antibody,
therefore can only bind to that specific antigen
Structure: 4 polypeptide chains, two identical sides, 2
binding sites; many different amino acid sequences
on binding sites for different purposes, different
combinations of antibody chains account for more
types of antibodies than there are genes (antibody
diversity)
Antibodies mark antigen for non-specific destruction
by binding to them
May bind multiple antigens together for easy
destruction, or mark them for other cells to destroy—
complement system
Once bound to an antigen, cell
multiplies into 2 types of cell:
Plasma cells
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Produce more of the same antibody to fight specific
antigen, short lifespan
Memory B cells
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Exist to respond if antigen returns to body, less of these
made
T cells
Produced in bone marrow, Develop in thymus (just above
heart)
Cell-mediated immune response
Produce chemicals that produce and maintain an immune
response
T-cell receptors on surface
activate when parts of an antigen are recognized on an
MHC protein—both occur on the surface of a cell that is
infected by a virus
Differentiate between foreign and self by recognizing HLA
molecules on a cell…all cells of the body except for red
blood cells have a different combination of these
molecules on their surface—tolerance
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Organ transplant—more successful if HLAs of donor and
recipient are mostly identical (lesser immune response)
Types of T cell:
CTLs—Cytotoxic T lymphocytes
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Limit viral infections by killing virus-infected cells
TH—Helper T cells
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Produce cytokines, which stimulate other lymphocytes to
reproduce
Speeds up production of B plasma cells, which in turn
boosts release of specific antibodies into the bloodstream
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Th1—stimulate cytotoxic response
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Th2—stimulate antibody response
video
Immune memory
Long-term resistance to repeat offenders—clonal
selection
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Primary immune response—when first exposed to antigen
Secondary immune response—reaction using memory B
cells
Antiviral drugs—prevent virus from reproducing
Antibiotics—attack bacteria
Vaccines
dead or weakened organisms that make body create
immunity without organism actually getting infected
Inactivated=unable to reproduce
Attenuated=unable to cause disease
Chicken pox, smallpox, measles, mumps, Hepatitis A
and B, rabies, rubella, typhoid, tuberculosis
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Edward Jenner—cured smallpox
Louis Pasteur—vaccine for rabies and others
Currently research occurring for a vaccine for AIDS
Immune system malfunctions
Immune suppression
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Medication and illegal drugs
Infectious agents—HIV
Immune hyperactivity
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Allergic reactions—poison ivy, metallic, asthma, seasonal
allergies
Autoimmunity
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Body attacks its own cells—rheumatoid arthritis, MS, diabetes
Caused by combination of genetic susceptibility and
environmental factors
Leukemia
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Lymphocytes turn cancerous, malfunctioning lymphocytes crowd
out normal ones and decrease immune system
May break off into bloodstream or bone marrow
HIV/AIDS
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HIV=human immunodeficiency virus
AIDS=acquired immunodeficiency
syndrome
HIV/AIDS
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Affects helper T cells, sometimes macrophages
and nerve cells
Attachment site: CD4 protein, attaching protein:
gp 120
Viral infection…(steps review?)
Result: decrease in helper T cells, greatly
weakens immune system; constant war between
helper T cells and HIV
Why no cure?
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Retrovirus—RNA material, mutation
Most of life cycle inside cells
video
Works Cited
"Discovery Health "How Your Immune System Works"" Discovery Health "Health Guides"
Web. 13 June 2011.
<http://health.howstuffworks.com/humanbody/systems/immune/immune-system11.htm>.
Greenberg, Jon. BSCS Biology: a Molecular Approach. New York: Glencoe McGraw-Hill, 2001. Print.
"HIV, AIDS and the Immune System." Information Technology. Web. 13 June 2011.
<http://people.ku.edu/~jbrown/hiv.html>.
Leukocyte functions. Digital image. Immune Cell Survival: Walking a Tightrope. Web. 13 June 2011.
<http://lpi.oregonstate.edu/sp-su98/images/immune1.gif>.
"Untitled Document." University of Virginia | Department of Biomedical Engineering (BME).
<http://bme.virginia.edu/ley/leukocytes.html>.
Web. 13 June 2011.
YouTube - 3D Medical Animation: Antibody Immune Response. YouTube - Broadcast Yourself.
June 2011. <http://www.youtube.com/watch?v=lrYlZJiuf18>.
Web. 13
YouTube - HIV Destroys Helper T-cells | Biology | Anatomy | Immunology. YouTube - Broadcast
Web. 13 June 2011. <http://www.youtube.com/watch?v=U2h0ECyMWhE>.
Yourself.
YouTube - Introduction to How the Immune System Works | Biology | Anatomy | Immunology. YouTube - Broadcast
Yourself. Web. 13 June 2011.
<http://www.youtube.com/watch?v=IWMJIMzsEMg>.
YouTube - Macrophages, B-cells, Pathogens, Antibody Immune Response. YouTube - Broadcast
Web. 13 June 2011. <http://www.youtube.com/watch?v=iDYL4x1Q6uU>.
Yourself.