Transcript Lymphatic System

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It carries fluid from the
extracellular space to the
bloodstream.
It defends the body
against disease.
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Circulatory system: carries lymphocytes,
macrophages, antibodies, etc in the blood.
Integumentary system: skin is first line of
defense, also contains mucous membranes.
Endocrine system: thymus and WBC
production, hypothalamus and fever.
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Physical Barriers:
Skin: first line of defense
 Mucus membranes: in addition to being a
barrier, they produce chemicals that may trap
microorganisms
 Infection: Invasion by a pathogen that
penetrates the body’s physical barriers
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Phagocytosis: ingestion & destruction of
particles by specialized cells
Phagocyte: Any cell that performs phagocytosis
 Monocytes and neutrophils: most active WBC in
phagocytosis – These cells are wanderers
 macrophages: Often attached. Mononuclear
phagocytic system- lymphatic fluid or blood
moves by them, the cells phagocytize foreign
particles cleaning the passing fluid.
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Natural Killer Cells: WBC that kills invading
foreign cells nonspecifically other than by
phagocytosis. They kill cancer and virus
infected cells by puncturing a hole in the
membrane. (due to the change in MHC
proteins)
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Proteins:
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Complement: includes more than20 types of plasma
proteins that are normally inactive but become
activated by the presence of infection. It then labels
the invaders so that the phagocytes will attack.
Interferon: Main defense against viruses. Cells
infected by viruses secrete them. This causes them
to diffuse to nearby cells and bind to their
membranes. Some how this inhibits proliferation of
the virus.
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Inflammation: prevents spread of infectious
agent, removes dead and damaged cells and
prepares for tissue repair. Damaged cells
release substances into the blood stream
(histamine, serotonin) this causes vasodilation
and increase in permeability of blood vessels. =
redness, swelling, heat, pain.
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Edema: fluid leakage into extracellular space
Pus: living and non living WBC, platelets, fibrinogen
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Components of Immunity:
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Antigens: substances that provoke an immune
response when they enter the body. Could be an
organism, toxin, foods, transplanted tissue, etc.
Sometimes the body recognizes own cells as
antigens = autoimmune disease
Antibodies:
antigen-antibody complex: a complex that
inactivates the effects of the antigen. Produced by
lymphocytes
 immunoglobins (Ig): Proteins with distinct structure
involved in different responses.
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Lymphocytes: WBC produced in the red
bone marrow before birth.
T-cells
 B-cells
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T-cells: The ½ of the lymphocytes that migrate
to the thymus mature into T-cells. They then
migrate to the lymphoid tissue in lymph nodes,
spleen, bone marrow, etc. They go through
mitosis to replicate. They are very active in
destruction of nonself cells.
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Killer T- cells: specialized in destroying virusinfected cells, cancer cells, and foreign cells. They
bind to the non-self cells and release a toxin that
causes lyses (cytolytic T-cells)
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Helper T-cells: Stimulate defense of other cells.
When an antigen is identified, they release proteins
into the blood that signal other cells to attack
(lymphokines). Stimulate killer T cells to grow and
divide, attract neutrophils and monocytes. They
also stimulate the division of B cells and their
production of antibodies.
Suppressor T-cells: slow the defensive mechanism
called into action by the helper T cells. This
prevents uncontrollable activity that can lead to
destruction of healthy self cells.
Memory T-cells: provide a memory of the specific
antigen that caused the initial sensitization.
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B Cells: mature B cells develop from the red
bone marrow, spleen, or intestinal wall.
They migrate to the lymph nodes and other
lymph tissue and accumulate. Sensitization
occurs when macrophages bind to an
antigen and than process it and express the
antigen on its plasma membrane.
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Cell- Mediated Immunity: Provided by T-cells. 1.
Macrophage IDs antigen. 2. Processes it. 3. Antigen
expressed on the membrane. 4. Macrophage
presents the antigen to T-cell = T-cell sensitization.
5. T-cell proliferates into varieties of T-cells. The
killers can only kill one specific nonself cell. The
lymphotoxins can’t finish the job on their own.
Assisted by helper T-cells that release lymphokines
that call phagocytes into action. This stimulates
production of more killer cells and activates humeral
immunity. Memory cells serve as rapid recall in
subsequent invasions.
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Humoral Immunity: B-cells provided.
Macrophage id’s an antigen in the body,
phagocytizes it and processes it. Presents
nonself substance to a B cell. Sensitization
and production of B cell lines with help from
helper Tells. Become antibody secreting
plasma cells and memory B cells.
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Humoral Immunity:
The Allergic Response: most have a tolerance
for many oneself molecules that come into
contact with the skin. 10% of individuals are
intolerant of many of these antigens = allergic.
 Plasma cells secrete a different type of antibody
IgE (norm IgG or IgM) the IgE antibodies are
secreted into the blood come into contact with a
mast cell= inflammation, mucus production and
hives “anaphylaxis”
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Acquired Immunity: ability to mount a defense
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Acquired Immunity: result of previous contact with
antigen
Natural Acquired Active Immunity: exposure to
pathogens or toxins during daily living. Symptoms
of disease expressed the first time because
immunity was not acquired before then.
Naturally Acquired Passive Immunity: antibodies
transferred from an immune person. (pregnancy)
short-lived
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Artificially Acquired Active Immunity:
deliberate artificial introduction of an antigen
stimulated immune response. Vaccine
 Artificially Acquired Passive Immunity: Shortlived immunity – human or animal antibodies
may be injected to provide active defense
Immune serum globulins.
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It takes time for the body to respond to the
invasion or a virus.
The body must first recognize then produce
lymphocytes against the new virus.
Once these have been made it takes time for
these cells to then destroy all of the infected
cells.
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After the initial exposure your body has
created lymphocytes and antibodies against
that invader so that if you are infected again
the body is able to respond immediately,
halting the infection.
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They provide a weakened/dead version of
an invader that posses little threat to the
body but enables the body an opportunity to
recognize and form lymphocytes and
antibodies against it.
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Some invaders mutate while they are in the body
making it necessary to have a T-cell for each new
version. (HIV & Influenza)
Invaders can produce molecules that inhibit actions
of certain leukocytes.
They can create molecules the disrupt the antigen
presentation process so that the T-cells never bind
or never even meet up with the invader.
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Inflammation is swelling in the area of
stress or a disruption to homeostasis that
can follow an injury or infection.
It aids in the prevention of spreading the
infectious agent to nearby tissues and
increases the amount of defensive
substances (WHB, antibodies, clotting
proteins) in the area.
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Pus is a liquid containing blood plasma,
dead or dying leukocytes and body cells as
well as other cell debris that forms during
inflammation.
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The spleen is responsible for creating
lymphocytes, removing foreign particles,
and damaged cells as well as acting as a
blood reservoir.
A person who has lost their spleen is more
susceptible to infections and must have
more immunizations or may be put on an
antibiotic regimen. The liver takes over the
filtering job of the spleen.
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The tonsils can cause common and
recurrent tonsillitis (sore throat).
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Germ theory states that microorganisms are
the cause of many illnesses.
It is important to study the impact of
different microorganisms on the body as
well as ways to prevent infection.
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Children get sick because they haven’t
formed antibodies against common
invaders. In daycare they are exposed to
more people who may be carrying other
illnesses. It wouldn’t any different than
when an child initially enters school (just a
few years earlier).
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Lymphedema is the swelling of lymphoid
tissue disrupting the flow of interstitial fluid
back into the circulatory system.
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The body is continually fighting the AIDS
virus lowering its disease fighting ability
against other invaders.
HIV targets helper T-cells and destroys
them. It can destroy 60-90% of all helper Tcells and suppresses cell-mediated
immunity.
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The immune system recognizes the organ as
a foreign invader and will attack and
possibly destroy all the tissue if the
individual is not given immune system
repressing drugs.
Individuals on these drugs are more likely to
get outside infections if not also put on an
antibiotic regimen.
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Severe combined immunodeficiency (SCID):
When an individual is born with the
inability to produce active T & B cells.
DiGeorge’s Syndrome: a congenital disease
in which the child is born without the
thymus or parathyroid gland.
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It suppresses the immune system by the
release of adrenaline and cortisol (antiinflammatory) as well as the reducing of
blood flow to any non-essential areas.
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The immune system struggles to distinguish
between self and nonself cells.
Macrophages are slower to destroy bacteria
and cancerous cells. (Another reason why older
people are more likely to get cancer.)
T-cells respond more slowly
Fewer WBC
Less antibodies are produced per antigen.
(Why vaccines are less effective on older
people.)
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When a person is intolerant to the antigens
on the surface of a particular kind of
molecule.
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Bone Marrow:
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Thymus:
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Lymphocytes originate here before birth then move
to the thymus where they will mature.
Promotes maturity of lymphocytes into Tlymphocytes. Active only when immune response is
developing (birth -5 yrs).
Lymph Nodes:
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They filter lymph of bacteria, toxins, & viruses. The
macrophages also engulf damaged cells & cell
debris.
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Spleen:
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Removes foreign particles, old & defective cells &
platelets. It also acts as a blood filter and blood
reservoirs.
Mucosal Associated Lymphoid Tissue:
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Small concentrations of lymphoid tissue found in
various sites of the body such as the gastrointestinal
tract, thyroid, breast, lung, salivary glands, eye, and skin.
It is populated by lymphocytes such as T cells and B
cells, as well as plasma cells and macrophages, each of
which is well situated to encounter antigens passing
through the mucosal epithelium.
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Tonsils/ Adenoids:
Lymphoid tissue located in the throat region.
 It gathers & engulfs disease causing organisms
in the mouth & throat region.
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Appendix:
In fetuses in produces endocrine cells.
 In adults it is believed to assist with the
maturation of B-cells and production of
immunoglobin A antibodies. (Most active in 20’s
& 30’s)
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Peyer’s Patch:
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Contains lymphocytes & macrophages that help
identify & prevent microorganisms from
crossing the intestinal wall.
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