The Immune System
By Lexy Mcalpin
All Systems Go:
• The immune system is the body's defense
against infectious organisms and other
invaders. Through a series of steps called the
immune response, the immune system
attacks organisms and substances that invade
body systems and cause disease.
• The immune system is made up
of a network of cells, tissues,
and organs that work together
to protect the body. The cells
involved are white blood cells,
or leukocytes, which come in
two basic types that combine
to seek out and destroy
disease-causing organisms or
substances.
• The organs of the immune system are positioned throughout the
body. They are called lymphoid organs because they are home to
lymphocytes, small white blood cells that are the key players in
the immune system.
• Bone marrow, the soft tissue in the hollow center of bones, is the
ultimate source of all blood cells, including lymphocytes. The
thymus is a lymphoid organ that lies behind the breastbone.
• Lymphocytes known as T lymphocytes or T cells (“T” stands for
“thymus”) mature in the thymus and then migrate to other
tissues. B lymphocytes, also known as B cells, become activated
and mature into plasma cells, which make and release antibodies.
• Lymph nodes, which are located in many parts of the body, are
lymphoid tissues that contain numerous specialized structures.
• T cells from the thymus concentrate in the paracortex.
• B cells develop in and around the germinal centers.
• Plasma cells occur in the medulla.
•Bone Marrow
All the specialized cells of the immune system are
formed in the bone marrow, where they mature. When
they are fully mature they move into the blood stream
where they do their work.
•Thymus
This small but important organ is where
lymphocyte precursors become thymocytes, which in
turn mature into T-cells. In addition, the thymus actually
chooses which T-cells are best suited for the immune
system. The remaining ones are eliminated by the body,
assuring a healthy, effective immunity.
•Spleen
You can think of the spleen as a filter for the blood. It catches
foreign material in the blood and activates different types of immune
system cells.
•Lymph Nodes
The lymph nodes filter foreign material from the lymph fluid.
Fluid that drains from various tissues in the body collects in the lymph
system and passes through the nodes, being filtered as it passes.
T-Cells:
There are two subsets of T-cells: CD4 cells and CD8 cells. CD4
cells secrete factors that activate other white blood cells that participate
in the immune response. HIV attacks CD4 cells, damaging the body's
ability to initiate the immune response. CD8 cells are important in
directly killing tumor cells, viral infected cells and some parasites.
WHAT
functions
with
the
IMMUNE
SYSTEM.
• Skeletal System: The skeletal system makes up
the framework of the body and allows
movement for when our muscles contract. This
system protects internal organs and produces
blood cells. It also stores minerals such as
calcium and releases them into the body when
they are needed.
• The skeletal system provides the blood cells
that the immune system needs as a method of
transportation
• Integumentary System: The integumentary
system contains receptors that respond to
touch, regulates body temperature, and
protects the inside of the body from damage.
• The integumentary system works along with
the immune system in defending your body
against various diseases, for this system fights
infection on the outside of the body.
• Circulatory System: The circulatory system is
responsible for transporting materials, such as
nutrients, water, and oxygen, throughout the entire
body. It transports those materials to billions of body
cells and carries away wastes such as the carbon
dioxide that body cells produce.
• The immune system works closely with the
circulatory system for transportation needs by means
of blood cells, allowing the immune cells to travel
throughout the body and survey the body for
infection.
WHAT KIND?
• What is natural and acquired immunity?
1. Natural immunity is created by the body's natural
barriers, such as the skin, and protective substances
in the mouth, the urinary tract, and on the eye
surface. Another type of natural immunity is in the
form of antibodies passed on from mother to child.
2. Acquired immunity develops through exposure to
specific foreign particles which are "remembered" by
the body's immune system. When that antigen enters
the body again, the immune system "remembers"
exactly how to respond to it.
Active and Passive Immunity
Active immunity
Lymphocytes are activated by antigens on
the surface of pathogens
Natural active immunity - acquired due to
infection
Artificial active immunity – vaccination
Takes time for enough B and T cells to be
produced to mount an effective response.
Active and Passive Immunity
Passive immunity
B and T cells are not activated and plasma
cells have not produced antibodies.
The antigen doesn’t have to be encountered
for the body to make the antibodies.
Antibodies appear immediately in blood but
protection is only temporary.
Active and Passive Immunity
Artificial passive immunity
Used when a very rapid immune response
is needed e.g. after infection with tetanus.
Human antibodies are injected. In the
case of tetanus these are antitoxin
antibodies.
Antibodies come from blood donors who
have recently had the tetanus vaccination.
Only provides short term protection as abs
destroyed by phagocytes in spleen and
liver.
Active and Passive Immunity
Natural passive immunity
A mother’s antibodies pass across the
placenta to the foetus and remain for
several months.
Colostrum (the first breast milk) contains lots
of IgA which remain on surface of the
baby’s gut wall and pass into blood
Homeostasis:
• The lymphatic system, also known as the
immune system, is responsible for protecting
the body from foreign invasion. Lymph, lymph
nodes, vessels, tonsils, thymus and the spleen
all comprise the organs of the lymphatic
system to help keep temperature maintained,
and bodily fluids free from foreign particles
maintaining homeostasis.
FUN FACT!
Lack of immune system response
indicates immunodeficiency!
This may be acquired through
family genetics
or may be acquired through
infection
(Mrs. Sullivan)
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