Download The Lymphatic System

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The Lymphatic / Immune System
Biology
Unit 8
Powerpoint #7
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Lymphatic System: Purpose:
Transports
a watery fluid called
lymph.
This
fluid distributes immune
cells throughout the body.
It
drains fluid from cells and
tissues
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Lymphatic System: Functions:
Collect
and return fluids,
including blood plasma, to the
blood, maintaining fluid
homeostasis.
Defends
the body against disease
by producing lymphocytes.
Absorbs
lipids from the intestine,
and transports them to the blood.
+ Why do we need the Lymphatic
System?
Every
24 hours the circulatory
system slowly leaks 3 liters of blood.
 Average
adult has ~100,000 miles of blood vessels if
you were to stretch them out in a line!
 The
earth’s Circumference is 25,000 miles long!
Lymphatic System: Structures:
 white
blood cells
(lymphocytes)
 Bone
marrow
 Thymus
 Spleen
 Tonsils
 lymph
nodes
 lymph
vessels
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Lymph / Lymph Vessels
Lymph:
fluid and protein that
has been squeezed out of the
blood (blood plasma).
Vessels:
A network of
permeable capillaries and
vessels that lymph drains into.
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Lymph Vessels
The
lymph system is one-way,
draining lymph from tissue,
back to the blood.
Lymph
movement depends on
smooth muscle action, and
skeletal system movement.
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Lymph Nodes:
 Filters
Lymph as is travels in the
lymph vessels.
 White
blood cells are located
within the lymph nodes.
 Bean-shaped, size
3mm to 2cm.
ranges from
 Can
become enlarged due to
infection.
A
combination burglar alarm
and West Point. They guard
against intruders, but also train
the ‘military’ to fight.
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White Blood Cells
Bone
marrow produces lymphocytes
Normally
in blood, but can be found at
any location.
Re-enter
blood circulation through
lymph vessels.
Fight
foreign invaders
(microorganisms)
Some
years.
last 2-5 days, others last for
+ Thymus:
Location of the
development of T-cell
lymphocytes.

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Spleen:
Fist-sized
mass of lymphatic
tissue that destroys old or
damaged red blood cells and
platelets.
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Immune System & Disease
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Disease- any change that disrupts normal body
functions (other than injury)
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Causes-
 Bacteria
 viruses
 fungi
 environmental
 genetically
Syndrome)
factors (smoke, lead, pesticides)
inherited (hemophilia, Down's
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Germ Theory of Disease

Proposed by Louis Pasteur & Robert Koch
Infectious
diseases are
caused by microorganisms
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Agents of Disease
Virus-
tiny particles
that invade & replicate
within living cells
Is
not alive, only a
piece of DNA or RNA
bound in a protective
coat
Agents
of
Disease
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Bacteria-
single celled
organisms (prokaryotic)
Most
don’t cause disease
Those
that cause disease
attack cells directly or
produce toxins that harm
cells
Agents of Disease
 Protists-
tiny single
celled organisms that
spread via insects,
blood, food, or water
 Examples:
Malaria,
Sleeping sickness,
traveler’s diarrhea
Agents of Disease
 Worms--
flatworms &
roundworm eggs that
grow inside other
organisms
 Examples:
Schistosoma
 Ascaris
 tapeworm
Agents of Disease
Fungi–
most are
harmless
Tinea
attacks the skin
causes athlete’s foot &
ringworm
Spread of Disease
Coughing,
sneezing, or
physical contact
Contaminated
food & water
Animals
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Fighting Infectious Disease
1. Antibiotics– compounds that kill bacteria
without harming host cells
 Many
are produced naturally by organisms (like
mold creates penicillin) discovered by Alexander
Fleming
2. Antiviral drugs– inhibit their ability to invade
cells
3. Rest & fluids so your own immune system can
work well!
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The Immune System

Immunity- fighting off disease before it
actually makes you ill

2 categories:
1.
Specific- targeted for 1 disease
2.
Nonspecific- general line of defense
against anything
Defense
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A.
First line of defense
1.
2.
3.
4.
Skin
a. Layers of dead cells are hard to penetrate
b. Oil and sweat  acidic environment kills
many bacteria
Mucus: traps dirt and pathogens
Stomach acid: destroys pathogens
Secretions (tears, sweat): lysozyme
breaks down cell walls of bacteria
nd line of defense
2
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
Inflammatory response–
1.
Phagocytes (white blood cells)
go to site of injury to engulf foreign agents
2. Fever can slow down growth or stop growth
of some pathogens (also ‘s heart rate
to get WBC’s to site faster)
3. Interferon proteins help cells resist viruses
by slowing down their replication in cells
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II. Specific Defenses
Humoral Immunity
1.
2.
3.
4.
Antigen: molecule on the surface of foreign
cells that causes an immune response
Antibody: protein that binds to antigens to
mark pathogens for destruction
Macrophage: large white blood cell that
engulfs foreign cells
Phagocyte: white blood cell that engulfs
foreign cells
Step in Immune
Response
1. Pathogen
invades the body
2. Macrophage
samples foreign
cells, engulfs
pathogen.
Labeled Drawing
Step in Immune
Response
3. Antigens from the
pathogen are
displayed on the
surface of the
macrophage.
4. T-cell recognizes
and is activated by the
amino acid sequence
of the antigens on the
macrophage.
Activated T-cell
replicates.
Labeled Drawing
Step in Immune
Response
5. T-cells activate Bcells which make
antibodies.
6. Antibodies bind
antigens on
pathogen –
inactivate pathogen
and mark it for
destruction by
phagocytes.
Labeled Drawing
Step in Immune
Response
7. Phagocytes
consume labeled
pathogens.
Labeled Drawing
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II. Specific Defenses
Permanent Immunity: once the body has
been exposed to a specific pathogen,
memory B and T cells remain capable of
producing antibodies to that pathogen
+ II.
Specific Defenses
C. Vaccination: injection of a weakened
form of a pathogen to produce
immunity
1. active immunity: produced by vaccine;
body is capable of producing antibodies to
a pathogen
2. passive immunity: antibodies produced
by another organism are injected; recipient
is immune as long as antibodies remain in
circulation
3. maternal immunity: antibodies are
passed from mother to fetus or infant;
similar to passive immunity
Passive
Immunity
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 Lasts
only a short time because they are not
created by the body’s own immune system

Examples:
1) Mother passing antibodies through placenta or breast milk to baby
2) Vaccines with antibodies against diseases like malaria, yellow fever,
rabies
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HIV & T-cells
 HIV
replicates inside Tcells, and then destroys
them as they burst open to
release more viruses
 When
Immune cells are
destroyed, other diseases &
infections can weaken & kill
AIDS patients
Immune
System
Disorders
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Allergies- overreactions of immune
system to antigens
 Mast
cells are specialized cells that initiate
the inflammatory response
 Histamines-
chemicals released by mast
cells that increase blood flow & fluids to the
area
 This
causes sneezing, watery eyes, & runny
nose
Autoimmune Diseases
 Body
attacks the body’s own
cells
 Examples:
Type I diabetes,
rheumatoid arthritis,
myasthenia gravis, &
multiple sclerosis (MS),
Lupus