What Are Lymph Nodes?

Lymph nodes are small glands all around your body that are part of your immune system. You’ve probably heard of lymph nodes—if you’ve heard of them at all–in relation to cancer diagnoses, but everyone has them, and they play a crucial role in keeping us healthy.

But what exactly are the bean-shaped nodes? In this video, we’ll explain everything you need to know about lymph nodes. Technically a part of the lymphatic system, a network of organs, vessels, and nodes throughout the body, lymph nodes act like filters, trapping bacteria, viruses, and other invaders before they can cause an infection.

Lymph nodes also control the transport of infection-fighting liquid called lymphatic fluid around your body, delivering white blood cells via lymph vessels (similarly to how veins transport blood).

Lymph nodes are concentrated in the neck, under the chin, in the armpits, and around the groin, and you might notice they get swollen if you’re fighting an infection in the area. Think back to the last time you had a sore throat—if you felt swollen bumps under your jawbone, you may have been feeling your lymph nodes. Strep, mono, and even a common cold can cause some swelling in lymph nodes, but it’ll usually go away when the infection clears up.

Lymph nodes might also get swollen if you have cancer. Cancer can start in or spread to the lymph nodes, but the lymph nodes are always involved in how doctors classify cancers into stages. The stage is usually determined in part by whether or not cancer has spread to nearby lymph nodes and how many of those nodes are affected. Some of those lymph nodes might need to be biopsied or removed entirely with surgery. Watch the video above for more information on what happens if you have lymph nodes removed—and how to limit lymph node swollen.