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Overview of the Lymphatic System

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The Manual's Editorial Staff

Last full review/revision Sep 2019
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What is the lymphatic system?

The lymphatic system is a network of lymphatic vessels and lymph nodes that carry fluid called lymph. The lymphatic system is part of your immune system, which helps defend against infection and cancer.

Lymph is fluid that oozes out of your tiniest blood vessels. The fluid goes between your cells and brings nourishment and carries away damaged cells, cancer cells, and germs.

Lymphatic vessels are tiny tubes that carry lymph from your tissues to lymph nodes and then from the lymph nodes back into your blood vessels.

Lymph nodes are collection points full of specialized white blood cells that filter out the germs and cells from lymph. These nodes and white blood cells help your body defend against infection and cancer. That's why sometimes an infection or cancer makes nearby lymph nodes swell up. For example, a throat infection can make lymph nodes in your neck swell up. People call these "swollen glands," but lymph nodes aren't really glands.

You have lymphatic vessels all around your body. Lymph nodes tend to cluster in certain places such as on the side of your neck, under your arms, or in your groin.

Lymphatic System: Helping Defend Against Infection

The lymphatic system is an important part of the immune system. The system carries lymph throughout your body, and your lymph nodes filter out dead germs and cells.

Lymphatic System: Helping Defend Against Infection

What is the immune system?

The immune system is your body's defense system. The immune system's job is to attack things that don’t belong in your body, including:

  • Germs, such as bacteria, viruses, and fungi

  • Parasites

  • Cancer cells

  • Other things that can get inside your body, such as pollen

The important parts of your immune system include:

  • White blood cells

  • Antibodies

  • The lymphatic system

What can go wrong with the lymphatic system?

The lymphatic system may not work well because of:

  • Blockage: If lymph vessels or nodes become blocked because of surgery, radiation therapy, injury, or infection, lymph builds up and causes swelling called lymphedema

  • Infection: If your body can't kill all the germs brought to a lymph node, the lymph nodes themselves can become infected

  • Cancer: If your body can't kill all the cancer cells brought to a lymph node, cancer can grow in the lymph nodes

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