What is the Lymphatic System?

Mary McMahon
Mary McMahon

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 all over again.

The lymphatic system is an interconnected system of vessels, nodes, and spaces in the body.
The lymphatic system is an interconnected system of vessels, nodes, and spaces in the body.

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, this 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 nodes help isolate the agent responsible for sickness in the body.
Lymph nodes help isolate the agent responsible for sickness in the body.

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.

The lymphatic system, shown in green.
The lymphatic system, shown in green.

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.

Swollen lymph nodes are one of the first signs of illness.
Swollen lymph nodes are one of the first signs of illness.

Damage or interruption to this 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.

Elephantitis refers to the abnormal enlargement of extremities as a result of blockages in the lymphatic system.
Elephantitis refers to the abnormal enlargement of extremities as a result of blockages in the lymphatic system.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments

anon330641

It was very informational for lymph, but I never found what the lymph nodes did, or what role the spleen or liver played in the lymphatic system.

anon80003

many thanks to the author of this article. and no, the lymphatic system doesn't have a pump, it relies on muscle contractions and natural movement to travel throughout the body.

Plasma exits the capillaries and becomes interstitial or intracellular fluid. When this fluid eventually enters the lymphatic vessels, it becomes lymph, therefore it's the same fluid throughout but depending on where it's located it's called a different thing.

To answer your question, yes lymph is located in the plasma because it is plasma.

anon75974

I found what I needed. So good job. thanks.

showoff123

Why do lymph nodes in the stomach get infected? And why would they cause continued severe vomiting?

anon25019

Is lymph located in the plasma?

anon15851

what is the pump for the lymphatic system?

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