Lymph Nodes Definition and Overview

Definition and Function of Lymph Nodes

image of the human body with the location of lymph nodes
What are lymph nodes and why are they important?. istockphoto.com

Definition: Lymph Nodes

Lymph nodes are small, bean-shaped glands that are located along the lymphatic system (a system of vessels similar to arteries and veins that lymph fluid travels through).

Location and Structure

Lymph nodes are small "masses" of tissue that lie along the lymphatic vessels of the body. You can think of them as rest stops along the lymphatic highway. These highways are the routes that our immune response uses to survey the body, similarly to how our blood system has highways that carry oxygen and nutrients to the body.

You may think of lymph nodes in your neck when you think of lymph nodes, but these nodes are located throughout our bodies.

Lymph Node Function

Lymph nodes work to as "sieves" or more like security guards to filter bacteria, viruses, parasites, other foreign material, and even cancer cells from the body. This is the reason that lymph nodes are evaluated in people with cancer, as this is the first place where cancer cells may be "caught" on their journey to explore and set up home elsewhere in the body.

"Swollen Glands"

Lymph nodes are well-known as the "swollen glands" people may note in their neck when they are fighting a cold or sore throat. If you are thin you may be able to feel lymph nodes in your groin as well. Not all lymph nodes are "palpable" which means that you cannot feel all of the lymph nodes in your body.

Conditions Involving Lymph Nodes

There are many conditions in which lymph nodes become involved.

 Some of these include:

  • Infections - Since lymph nodes store white blood cells which are our first line of defense against infection, they are often enlarged due to activity with infections. Enlargement of lymph nodes with an infection can be good or bad. It is good in the sense that they are the powerhouses storing immune cells. In other words, enlargement of the lymph nodes may mean your body is doing its job to resolve infection. We didn't always know this. An example is with the tonsils which are similarly immune tissue. For a long time, it was thought that removing the tonsils would help prevent strep throat. It is true that if an infection has messed up the glands, removing them is a good idea. But it was also found that removing the tonsils could result in infections farther down the line. What we were doing is removing the functional first place where bacteria would travel.
  • Cancer - Lymph nodes are enlarged in many cancers and this can be related to cancer cells from a blood cancer such as lymphoma, or due to other cancers in the body which have spread.
  • Trauma - Since the lymph nodes are the rest stops for the "workers" - the white blood cells which clean up a site of trauma, they are often enlarged with any injury. You can think of the lymph nodes as being a truck stop near a natural disaster where the firemen and paramedics are hanging out ready to do their job.

Lymph Nodes in Lung Cancer

With lung cancer, cancer cells can spread through the lymphatic system and become trapped in lymph nodes. Determining which, if any, of these nodes contain cancer cells help doctors determine the stage of a cancer -- that is, how far the cancer has spread. Subsequently, they can choose the best treatment.

Further Reading:

Also Known As: lymph glands

Examples: To determine the stage of her lung cancer, Joan's doctor told her he would need to see if it had spread to any of her lymph nodes.

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