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The Lymphatic System
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What Does the Lymphatic
System Do?
carries dissolved
oxygen and nutrients to
the cells.
Collects cellular waste
Plays an important role
in the immune system.
What Is the Lymphatic System?
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A system of thin tubes that
run through the body
called lymph vessels
The liquid that is inside
these vessels is called
lymph.
Lymph comes from
extracellular fluid.
Extracellular Fluid
Plasma leaks out of
capillaries and fills
empty spaces
between blood
vessels and tissues.
 The leaked plasma is
called extracellular
fluid.
 It contains water and
other substances
from blood plasma as
well as white blood
cells.

This
fluid is collected by the
lymph vessels to make lymph.
Lymph is:
A fluid that fills the spaces
between the blood vessels
and body cells. It allows for
exchanges between blood
and body cells.
-circulates in the lymphatic
vessels to evacuate waste
from cells
Functions of the
lymphatic system
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To collect excess lymph and return
it to blood circulation; (along with
any waste that may be collected)
Fight infections: carries elements of
the immune system such as
antibodies and white blood cells
that will neutralize antigens (viruses
and bacteria);
Transports molecules of fat
Filters the blood and lymph
Lymphatic vessels
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Similar to blood vessels, they
are located near them;
They carry lymph and return
it to the blood by emptying it
into the two subclavian veins
(located near the heart);
– Right subclavian vein for
the upper part of the body;
– Left subclavian vein for the
rest of the body;
Lymph circulates as a result of
the contracting of the muscles
on the lymphatic vessels (like
blood in veins).
Lymph Nodes (ganglions)
Small round structures found along the lymph
vessels
 Found in 4 areas:
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– Groin
– Neck
– Armpits
– Abdomen
During an infection such as tonsillitis or the flu,
lymph nodes swell and harden
Lymph is filtered by lymph nodes which are
filled with white blood cells that attack
bacteria and viruses

They make white blood cells
Filtering Lymph
 The
lymph is filtered by the lymph
nodes
 In the lymph nodes are white blood
cells that attack bacteria and viruses
 Cancer cells often end up here
Organs That are Part of the
Lymphatic System:
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Spleen (abdomen, left
of stomach)
Tonsils (mouth
bordering pharynx)
Thymus (beneath heart)
Bone marrow (found in
long bones)
– All these organs are filled
with white blood cells that
filter blood and collect
harmful bacteria and
viruses
– This is how the lymphatic
system plays a role in
immunity;
Filtering Blood

The spleen filters the blood
– It destroys old worn out red blood cells
– It has white blood cells that attack viruses and
bacteria
The immune system
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Includes vessels and organs of the lymphatic
system as well as other structures or cells, such as
white blood cells, which help to protect the body;
Immunity: ability of the human body to protect
itself against foreign antigens;
Antigens are viruses, bacteria, abnormal cells or
any other substances that can trigger a reaction of
the immune system;
Antibody: substance produced by certain white
blood cells and that is able to neutralize a specific
antigen.
When the Lymphatic System Goes
Wrong
Elephantiasis
-Happens when the
lymphatic vessels
are blocked due to
a parasite
When the Lymphatic System Goes
Wrong
Lymphedema
-Happens when the
lymphatic vessels
are blocked
-This may be caused
by an injury to the
lymph vessels or it
may be inherited
Non-specific immunity
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Human body’s ability to protect itself against a
wide range of antigens (white blood cells)
Skin acts as a barrier and is one of the
mechanisms of non-specific immunity
Your lymph nodes or glands become swollen
when you are sick because they are working to
make cells to fight infections.
diapedesis is the process through which white
blood cells move outside of capillaries and enter
the lymphatic system to reach the site of
infection. White blood cells will circle the antigens
and form pseudopods
Once they reach the pathogen they surround and
destroy it through phagocytosis
EX: Otitis
 An
inflammation of the ear caused by
an infection.
 The infection is not in the blood
vessels, white blood cells move out
of the capillaries to fight the infection
Diapedesis
Phagocytosis
Specific immunity
Human body’s ability to protect itself against a
particular antigen using specific antibodies
1) Natural acquisition: ex. being exposed to an
infection like chicken pox. Cells of immune system
have a memory of the antibodies produced by white
blood cells to fight against the antigen causing the
infection. If the antigen enters the body again,
body can produce the specific antibodies quicker,
and the person will not develop the illness again
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2) Artificial acquisition: being given a
vaccine. Vaccines contain
dead/weakened antigens which trigger
the production and memory of
antibodies without causing the illness.
Vaccinated person has immunity to
that illness if they would encounter it.
**Vaccines do not cure you of
diseases – you need to be vaccinated
BEFORE getting sick!
Vaccines
 Were
investigated by Edward Jenner
in the 1700s.
 Later, Pasteur conducted a few
experiments on fowl cholera 0ver
100 years later
Vaccines Defined
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A dead or weakened bacteria or virus that is injected
into the blood
When introduced into the body, it stimulates the
immune system; which learns to protect itself from
the pathogen by making specific antibodies which
immunizes the individual against the disease.
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What are they used for?
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– To protect the health of the people that receive them which
will prevent them from developing diseases with dangerous
consequences
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How does it work?
– They contain antigens (bacteria, viruses, virus fragments,
etc.) that are weakened and cannot transmit disease. The
body still produces antibodies to eliminate these antigens
that will be effective if in contact with the real disease.
Pathogens
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Pathogens are viruses and bacteria.
Virus
Smallest pathogen
Bacteria
Single cell organisms
Invade cells
Reproduce quickly
Few drugs to fight
them
Produce toxins which
destroy cells
To kill the virus, you
must kill the cell
Can be killed with
antibiotics
Viruses & Bacteria
Vaccines: Facts
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If a vaccine is administered to an entire population,
epidemics can be prevented.
You can get vaccinated against diseases caused by
viruses, bacteria (measles, whooping cough, hepatitis B
and even chicken pox.
There are some vaccines recommended for children and
adolescents in Québec: DTaP-Polio-Hib, MMR and others.
There are some vaccines for adults: Gardasyl, influenza
and others.
There are some vaccines that need to be given to a
person traveling in tropical countries: hepatitis A and
typhoid.
Vaccine Manufacturing
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Attenuated vaccines are prepared from living
bacteria or viruses. Manufacturers select strains
that have lost their power to cause disease but
are still recognized as foreign (measles, rubella,
mumps etc)
Inactivated vaccines are prepared from
bacteria or viruses that have been inactivated or
killed by chemicals, heat or UV rays. No longer
pathogenic, but stimulate the immune system
(typhoid, cholera, etc)
Vaccines can also be prepared through genetic
manipulation, where scientists replace or
remove genes in viruses and bacteria that cause
disease (hepatitis B)
Different vaccines can sometimes have different
side effects
The Difference between
Antibiotics and Vaccines
• Antibiotics cure disease by killing or
injuring bacteria
• Although antibiotics are useful in a wide
variety of infections, it is important to realize
that antibiotics only treat bacterial
infections. Antibiotics are useless against
viral infections (for example, the common
cold) and fungal infections (such as
ringworm).