Download The Immune System and Its Functioning

The Immune System and Its Functioning
Infants are given their first vaccinations shortly after birth. Children receive rounds of
immunizations long into adolescence. These vaccines indeed protect us, but the body already
possesses an effective defense system. The immune system is a bodily system, made up of
organs and vessel systems, which protects us from foreign substances such as bacteria and
viruses. This system produces white blood cells and antibodies which attack and destroy foreign
substances. Let’s take a closer look at the different body parts that make up the immune system.
Components of the Immune System and their Functions
Tonsils and Thymus
As you can see in the figure, the tonsils are
located in the throat. This location allows
their defense cells to quickly target
pathogens and activate the immune system.
The Thymus gland produces antibodies.
Antibodies are proteins that eliminate
antigens which are substances found on cell
surfaces. The body contains some benign
antigens that the antibodies will not attack.
Lymph nodes and vessels
Lymph nodes and vessels work like a filter
system in the body. They form a network
throughout the body carrying nutrients and
waste material between body tissues and the
bloodstream. Lymph nodes filter the fluid as
it flows through them. Their job is to trap
foreign substances so that white blood cells
can come in and destroy them.
Bone Marrow
Bone marrow is soft tissue found inside the
long bones of our arms and legs as well as in
our vertebrae. Most defense cells, such as
white blood cells are produced and
multiplied in the bone marrow. These cells
then enter the bloodstream and are
transported to organs and tissues. From
there, these cells will mature and become
specialized.
Spleen
The spleen is located in the upper left side of
the abdomen. Its function is to remove old
or damaged blood cells and platelets from
the body. Platelets are responsible for blood
clotting, and are stored in the spleen. The
spleen aids the immune system by housing
defense cells that can directly attack foreign
substances while blood is being cleaned.
Also contained in the spleen are specialized
bodies that inspect cell surfaces.
-Components of the Immune System
Image adapted from
http://www.webmd.com/a-to-zguides/components-of-the-immunesystem
Immune Response
Innate Immunity
Innate or nonspecific immunity is the defense system we are all born with. It is also the
immune system’s first line of action in immune response. It protects us from all types of
antigens. The body’s innate immunity includes all barriers that block the entry of harmful
materials. If an antigen gets past the innate immunity it is up to other parts of the immune system
to attack and destroy it. Here are a few of the body’s innate immunities:
 Cough Reflex
 Skin
 Stomach Acid
 Mucous (traps bacteria and small particles)
An example of innate immunity in action is the body’s inflammatory response. This occurs when
tissues are injured by bacteria, toxins, or trauma. The inflammatory response causes blood
vessels to leak fluid into the damaged area. Then, the area will swell, allowing the foreign
substance to be isolated. White blood cells are attracted to the area and destroy the germs or
damaged cells.
Passive Immunity
Another type of immune response is passive immunity. The antibodies functioning in
passive immunity were produced somewhere other than your own body. Infants have passive
immunity because they are born with antibodies that were transferred through their mother’s
placenta. These antibodies will not remain in the body for very long. Most of the time they will
disappear between the ages of 6 and 12 months. We can also receive passive immunity by
injecting antibodies formed in another person or animal. These will provide an immediate
response to a particular antigen, but will not offer long term protection. An example of this type
of injection is a tetanus shot.
Acquired Immunity
Acquired Immunity is another mechanism the immune system uses to fight off antigens.
Acquired Immunity refers to the immune system’s ability to build up a defense against specific
antigens. Suppose an unknown bacteria has entered the body. The immune response will be
triggered, and the bacteria will be eliminated. The antibodies that were produced to eliminate the
bacteria will remain in the body. If this bacteria enters the body again, these new antibodies will
immediately locate and destroy all harmful cells.
The vaccinations we are given as children work in a similar way. Vaccines contain a
weakened version of a particular virus. The body will produce antibodies to destroy the virus.
Once again, these antibodies will remain in our bodies and will activate we ever come in contact
with the virus. It is a way of giving the body acquired immunity.
Blood Components of the Immune System
White blood cells, antibodies, and complement proteins are components of the immune
system found in the blood. Antibodies and white blood cells attack foreign substances directly,
while complement proteins work together to aid immune system cells. Lymphocytes are a type
of white blood cell. They are further broken down into B and T type lymphocytes based on their
function in the immune system. The B types produce antibodies that attach to antigens to aid in
their destruction. The T types attack antigens directly and help activate immune response. As
lymphocytes develop, they learn to tell the difference between normal body tissue and foreign
substances. This allows immune response to occur quickly and efficiently. The figure below
shows a T type attacking a cell infected by a virus:
-T type lymphocyte cell targeting and destroying a
virus
-
Image adapted from
http://www.wikidoc.org/index.php/Immune_system#cite_
note-NIAID-41
Immune System Disorders
A person’s immune system can be defective in two ways. The immune response towards
body tissue can either be excessive or lacking. You are especially susceptible to getting viruses if
your body lacks immune response. On the other hand, an example of an excessive immune
response to a foreign substance is an allergy. Allergies involve the body producing an immune
response to a substance that is otherwise harmless.
Conclusion
Our immune systems are made up of multiple body parts that work together as a team to
keep us safe from foreign substances. In order to optimize immune response, multiple types
exist. Specialized antibodies that are created to eliminate viruses or diseases remain in the body
so they can quickly diagnose future problems. Our immune systems are highly versatile and
adept at destroying germs. Vaccines can be helpful, but are not necessary. Perhaps you can save
yourself some time and pain and avoid getting all those shots.