What Is the Lymphatic System? The lymphatic system is part of the immune system. It keeps body fluid levels in balance and defends the body against infections. Lymphatic (lim-FAT-ik) vessels, tissues, organs, and glands work together to drain a watery fluid called lymph from throughout the body. What Does the Lymphatic System Do? One of the lymphatic system's major jobs is to drain extra lymph (LIMF) fluid from body tissues and return it to the blood. Lymph contains white blood cells called lymphocytes (LIM-fuh-sites) and chyle (KYE-ul), which is made of fats and proteins from the intestines. This is important because water, proteins, and other substances are always leaking out of tiny blood capillaries into the body tissues around them. If the lymphatic system didn't drain it, this extra fluid would build up in the tissues and make them swell. What's in the Lymphatic System? Organs and tissues that are part of the lymphatic system include: bone marrow, the thick, spongy kind of jelly inside bones that makes many kinds of blood cells, including immune system cells thymus gland, which makes immune system cells called T cells, especially before and during puberty tonsils appendix lymph nodes Lymph nodes are small clumps of tissue along the network of lymph vessels that clean lymph as it moves through them. They filter out viruses, bacteria, and fungi that can cause illnesses. Most lymph nodes are in clusters in the neck, armpit, and groin area. They're also found along the lymphatic pathways in the chest, abdomen, and pelvis, where they filter blood. Inside the lymph nodes, T-cells and another type of lymphocyte, B-cells, help the body fight infection. B cells make antibodies — special proteins that stop infections from spreading by trapping disease-causing germs and destroying them. When someone has an infection, germs collect in the lymph nodes. If their throat is infected, for example, the lymph nodes in the neck may swell. That's why doctors check for swollen lymph nodes (sometimes called swollen "glands") in the neck when someone has a sore throat. When lymphatic nodes swell, it's called lymphadenopathy (lim-fad-n-OP-uh-thee). Lymphatic vessels, or tubes, are the pathways that carry lymph. The major lymphatic vessels are: The thoracic duct: It begins near the lower part of the spine and collects lymph from the pelvis, abdomen, and lower chest. The thoracic (thuh-RA-sik) duct runs up through the chest and empties into the blood through a large vein near the left side of the neck. The right lymphatic duct: It collects lymph from the right side of the neck, chest, and arm, and empties into a large vein near the right side of the neck. Back to Articles Related Articles Immune System The immune system, composed of special cells, proteins, tissues, and organs that protect against germs and microorganisms, is the body's defense against disease. Read More Lymphatic Malformations A lymphatic malformation is a clump of lymph vessels that form a growing spongy cluster. They're unusual growths, but are not cancerous. Read More Non-Hodgkin (Non-Hodgkin's) Lymphoma Non-Hodgkin lymphoma (also called non-Hodgkin's lymphoma) is a is a cancer of the lymphatic system. The majority of kids with this type of cancer are cured. Read More Tonsillectomy A tonsillectomy is surgery to remove the tonsils. It's one of the most common surgeries kids and teens get. Find out more. Read More Mononucleosis (Mono) Mononucleosis - or "mono" - is an infection that causes flu-like symptoms. It usually goes away on its own in a few weeks with the help of plenty of fluids and rest. Read More Lymphoma Lymphoma is cancer that begins in the body's lymphatic tissue. It's a common type of cancer in children, but most recover from it. Read More Tonsillectomy Everybody's heard of tonsils, but not everyone knows what tonsils do in the body or why they may need to be removed. Find out here. Read More Mononucleosis (Mono) It's sometimes called "the kissing disease," but kissing is just one of the ways that someone can catch mono. Read More Cat Scratch Disease Cat scratch disease is an infection that causes swelling of the lymph nodes after a cat scratch or bite. Learn about signs and symptoms, prevention, treatment, and more. Read More Hodgkin Lymphoma Hodgkin lymphoma is a type of cancer that affects the lymphatic system. Most kids and teens who get Hodgkin lymphoma get better. Read More Tonsillitis If your tonsils get infected, it can make your throat feel very sore. Find out more in this article for kids. Read More Spleen and Lymphatic System The lymphatic system is an extensive drainage network that helps keep bodily fluid levels in balance and defends the body against infections. Read More Blood Here are the basics about the life-sustaining fluid called blood. Read More What Are Glands? You've heard of glands, but what are they? Find out in this article for kids. Read More Word! Lymph Node Your wonderful lymph nodes! Lymph nodes are little round or bean-shaped bumps that you usually can't feel unless they become swollen. Read More Your Immune System The immune system keeps you healthy. How does it work? Find out in this article for kids. Read More Word! Lymph Lymph is a clear fluid that flows through its own vessels located throughout the body. Read More Chylous Ascites Chylous ascites is when chyle collects in the belly. Depending on what's causing it, doctors can treat chylous ascites and often cure it. Read More Chylothorax A chlylothorax happens when chyle (lymphatic fluid) collects in the space around a lung. Read More Chyluria Chyluria is when there is chyle in the pee. Depending on what's causing it, chyluria can be treated and often can be cured. Read More Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.