Spleen and Lymphatic System (page 2)

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).

Reviewed by: Yamini Durani, MD
Date reviewed: October 2012