The lymphatic system is an
extensive and interconnected system of vessels,
spaces, and nodes in the body which circulates
lymph, a fluid made from protein and other
fluids. Lymph is initially part of the blood,
but as blood flows through the body, lymph
slowly leaks out, taking hazardous substances
with it and filtering these substances through
the lymph nodes, which trap these substances.
Over time, the lymph slowly works its way around
the body, eventually re-entering the heart so
that it can be circulated a ll
over again.
Many people are familiar with
the circulatory system, which moves blood around
the body, but they may not be as familiar with
the lymphatic system, because it isn't quite as
flashy. However, the lymphatic system is still
extremely important, as lymph performs a number
of vital functions in the body, especially in
the context of the immune system. You have
probably seen your own lymph; if a cut has ever
oozed a clear fluid, that was lymph.
Lymph can be found all over the
body, filling the spaces between muscles,
organs, and other structures in the body, and
circulating through a series of valves which
allow the lymph to flow only in one direction.
Unlike the blood, lymph does not have a central
pump, relying instead on muscle contractions and
other natural functions of the body to force
lymph through the lymphatic system, where it
will eventually drain into the thoracic duct,
which brings lymph back to the heart.
How A Healthy
Lymph System Typically Works
Carrying Away Waste
Lymph fluid drains into lymph
capillaries, which are tiny vessels. The fluid
is then pushed along when a person breathes or
the muscles contract. The lymph capillaries are
very thin, and they have many tiny openings that
allow gases, water, and nutrients to pass
through to the surrounding cells, nourishing
them and taking away waste products. When lymph
fluid leaks through in this way it is called
interstitial fluid.
Lymph vessels collect the interstitial fluid and
then return it to the bloodstream by emptying it
into large veins in the upper chest, near the
neck.
Fighting Infection
Lymph fluid enters the lymph nodes, where
macrophages figh t
off foreign bodies like bacteria, removing them
from the bloodstream. After these substances
have been filtered out, the lymph fluid leaves
the lymph nodes and returns to the veins, where
it re-enters the bloodstream.
When a person has an infection, germs collect in
the lymph nodes. If the throat is infected, for
example, the lymph nodes of the neck may swell.
That's why doctors check for swollen lymph nodes
(sometimes called swollen "glands" — but they're
actually lymph nodes) in the neck when your
throat is infected.
Lymph generates several types of cells
which are important to the immune system, and it
also traps substances which the body identifies
as dangerous. It also plays a role in the
transport of fatty acids and other substances,
helping the digestive tract process food more
efficiently. As lymph circulates, passing
through the lymph nodes, it becomes more turbid,
abandoning potentially hazardous materials and
seeking others to quarantine to keep the body
healthy.
Damage
or interruption to the lymphatic system
can result in a range of medical conditions. You
may be familiar with lymphedema, a condition in
which lymph pools in the limbs because it cannot
circulate. Lymphoma is also related to the
lymphatic system, as the name implies, and
elephantiasis is also linked with disruption to
the lymphatic system. You may also notice that
your lymph nodes become swollen when you are
sick, because your body is isolating the agent
responsible to help you get better. |
