The lymphatic system is an extensive drainage network that helps keep
bodily fluid levels in balance and defends the body against infections.
It is made up of a network of lymphatic vessels that carry lymph — a
clear, watery fluid that contains protein molecules, salts, glucose,
urea, and other substances — throughout the body.

The spleen, which is located in the upper left part of the abdomen
under the ribcage, works as part of the lymphatic system to protect the
body, clearing worn out red blood cells and other foreign bodies from
the bloodstream to help fight off infection.

About the Spleen and Lymphatic System



One of the lymphatic system's major jobs is to collect extra lymph
fluid from body tissues and return it to the blood. This process is
crucial because water, proteins, and other substances are continuously
leaking out of tiny blood capillaries into the surrounding body tissues.
If the lymphatic system didn't drain the excess fluid from the tissues,
the lymph fluid would build up in the body's tissues, and they would
swell.

The lymphatic system also helps defend the body against germs like
viruses, bacteria, and fungi that can cause illnesses. Those germs are
filtered out in the lymph nodes, small masses of tissue located along
the network of lymph vessels. The nodes house lymphocytes, a type of
white blood cell. Some of those lymphocytes make antibodies, special
proteins that fight off germs and stop infections from spreading by
trapping disease-causing germs and destroying them.

The spleen also helps the body fight infection. The spleen contains
lymphocytes and another kind of white blood cell called macrophages,
which engulf and destroy bacteria, dead tissue, and foreign matter and
remove them from the blood passing through the spleen.Basic Anatomy



The lymphatic system is a network of very small tubes (or vessels)
that drain lymph fluid from all over the body. The major parts of the
lymph tissue are located in the bone marrow, spleen, thymus gland, lymph
nodes, and the tonsils. The heart, lungs, intestines, liver, and skin
also contain lymphatic tissue.

One of the major lymphatic vessels is the thoracic duct, which begins
near the lower part of the spine and collects lymph from the pelvis,
abdomen, and lower chest. The thoracic duct runs up through the chest
and empties into the blood through a large vein near the left side of
the neck. The right lymphatic duct is the other major lymphatic vessel
and collects lymph from the right side of the neck, chest, and arm, and
empties into a large vein near the right side of the neck.

Lymph nodes are round or kidney-shaped, and can be up to 1 inch in
diameter. Most of the lymph nodes are found in clusters in the neck,
armpit, and groin area. Nodes are also located along the lymphatic
pathways in the chest, abdomen, and pelvis, where they filter the blood.
Inside the lymph nodes, lymphocytes called T-cells and B-cells help the
body fight infection. Lymphatic tissue is also scattered throughout the
body in different major organs and in and around the gastrointestinal
tract.

The spleen helps control the amount of blood and blood cells that circulate through the body and helps destroy damaged cells.

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 fight 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.Problems of the Lymphatic System



Certain diseases can affect the lymph nodes, the spleen, or the collections of lymphoid tissue in certain areas of the body.

• Lymphadenopathy. This is a condition where the
  lymph nodes become swollen or enlarged, usually because of a nearby
  infection. Swollen lymph nodes in the neck, for example, can be caused
  by a throat infection. Once the infection is treated, the swelling
  usually goes away. If several lymph node groups throughout the body are
  swollen, that can indicate a more serious disease that needs further
  investigation by a doctor.
  
• Lymphadenitis. Also called adenitis, this
  inflammation of the lymph node is caused by an infection of the tissue
  in the node. The infection can cause the skin overlying the lymph node
  to swell, redden, and feel warm and tender to the touch. This infection
  usually affects the lymph nodes in the neck, and it's usually caused by a
  bacterial infection that can be easily treated with an antibiotic.
  
• Lymphomas. These cancers start in the lymph nodes
  when lymphocytes undergo changes and start to multiply out of control.
  The lymph nodes swell, and the cancer cells crowd out healthy cells and
  may cause tumors (solid growths) in other parts of the body.
  
• Splenomegaly (enlarged spleen). In healthy people,
  the spleen is usually small enough that it can't be felt when you press
  on the abdomen. But certain diseases can cause the spleen to swell to
  several times its normal size. Usually, this is due to a viral
  infection, such as mononucleosis. But in some cases, more serious
  diseases such as cancer can cause it to expand. Doctors usually tell
  someone with an enlarged spleen to avoid contact sports like football
  for a while because a swollen spleen is vulnerable to rupturing
  (bursting). And if it ruptures, it can cause a huge amount of blood
  loss.
  
• Tonsillitis. Tonsillitis is caused by an infection
  of the tonsils, the lymphoid tissues in the back of the mouth at the top
  of the throat that normally help to filter out bacteria. When the
  tonsils are infected, they become swollen and inflamed, and can cause a
  sore throat, fever, and difficulty swallowing. The infection can also
  spread to the throat and surrounding areas, causing pain and
  inflammation. A child with repeated tonsil infections may need to have
  them removed (a tonsillectomy).