Everything You Need to Know About the Lymphatic System

Medically Reviewed By Stacy Sampson, D.O.

The lymphatic system plays an important role in your body’s immune defense system. Here is an overview of the different parts of the lymphatic system. The lymphatic system helps protect your body against disease and infection. It is made up of a network of lymph nodes, lymph fluid, and lymph vessels. It also contains important structures and organs, such as the spleen, tonsils, thymus gland, bone marrow, and appendix. The lymphatic system produces and houses white blood cells that filter out and destroy pathogens.

This article will further define the lymphatic system. It will also discuss the system’s functions, its parts, and conditions that can affect it.

What is the lymphatic system?

Doctor checking a female's lymph nodes
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The lymphatic system is part of the body’s immune system that helps protect against infection and disease. It is made up of a network of:

  • lymph fluid
  • lymph vessels
  • lymph nodes

The lymph fluid flows through a network of lymph vessels, carrying waste products back into the bloodstream. The lymph vessels connect to a group of lymph nodes, which act as a filter. They trap or destroy anything harmful that the body does not need.

Sometimes, cancer cells can spread from their primary site of origin to the lymphatic system, specifically the lymph nodes. When this happens, it is called secondary cancer in the lymph nodes. Cancer can also start in the lymph nodes themselves, which is called lymphoma.

The most common sites where lymph nodes occur near the surface of the skin are the neck, armpits, and groin. They are also located deep inside the body, such as in the abdomen. When the lymph nodes are swollen due to illness, such as a cold or flu, they can be felt just underneath the skin.

Lymph nodes contain specialized white blood cells, called lymphocytes and macrophages, that engulf and destroy:

  • damaged cells
  • cancer cells
  • infectious organisms
  • foreign particles

The lymph fluid contains these foreign materials that strategically pass through the lymph nodes for filtration.

Click here to read about how sleep affects your immune system.

What are the functions of the lymphatic system?

The lymphatic system helps maintain your body’s fluid balance and helps protect you from infection and disease.

The primary functions of the lymphatic system are as follows:

  • It acts as the body’s sewage system, filtering out bacteria and harmful foreign material.
  • It maintains fluid levels in the body’s tissues by removing the fluids that leak out of the blood vessels.
  • It helps with the optimal functioning of general and specific immune responses.
  • It produces cells and stimulates the production of antibodies that protect the body from infection and disease.
  • It detects and responds to pathogens and malignant cells.
  • It plays a role in the absorption of fats from the intestine.

What are the parts of the lymphatic system?

The major parts of the lymphatic system are the spleen, tonsils, thymus gland, bone marrow, and appendix.


The spleen is the largest of the lymphatic organs. It is found on the left side of the abdomen, just under the diaphragm.

The spleen filters and monitors foreign material in the blood through white blood cells, called macrophages. It also stores other types of white blood cells that are important for your body’s defense.

In addition to removing microbes, the spleen destroys old or damaged red blood cells. It can help increase the volume of red blood cells if you lose a lot of blood.


Tonsils are clusters of lymphatic tissue under the mucous membrane lining of the nose, mouth, and throat.

The tonsils contain white blood cells, called lymphocytes and macrophages. These provide protection against bacteria and other germs that enter the body through the mouth or nose.

Thymus gland

The thymus gland is located inside the ribcage, just behind the breastbone. It is another organ that filters and monitors foreign material and harmful substances in the blood.

The thymus produces cells called T lymphocytes, which are part of the immune response when the body has an infection.

Bone marrow

Bone marrow is spongy tissue located in the middle of some of the bigger bones in the body, such as the:

  • thigh bone
  • breastbone
  • hip bone
  • spine

The bone marrow makes blood cells from stem cells. Stem cells are undeveloped cells that divide and grow into the different types of blood cells that the body needs, such as:

  • red blood cells
  • platelets
  • white blood cells

B lymphocytes are a type of fully mature white blood cell that are made in the bone marrow.


The appendix is a thin tube that connects to the large intestine. It sits in the lower right part of the abdomen. The appendix acts as monitor of bad versus good bacteria.

Good bacteria, the kind found in the stomach and intestines, help break down the food you eat. They stave off bad bacteria. They also play a role in processing the vitamins and minerals your body needs.

The appendix helps reboot the intestine with good bacteria before harmful bacteria find a home there.

What are common problems related to the lymphatic system?

If the lymphatic system is not functioning properly, it can lead to problems, such as obstruction, infection, and cancer.

Some of the most common problems related to the lymphatic system include:

  • Lymphedema: This is an accumulation of fluid in the lymphatic system that occurs due to an obstruction or blockage. Obstruction in the lymphatic vessels can occur from scar tissue that develops when the lymph nodes are damaged or removed during surgery, radiation, or injury.
  • Lymphadenitis: This is inflammation of the lymph nodes. Infection can cause the lymph nodes to become swollen due to inflammation. Infection can occur due to organisms that spread throughout the lymphatic system from the original site of infection.
  • Lymphoma: Cancer of the lymphatic system can occur in two ways. One way is when white blood cell cancer develops in the lymph nodes. Another way is when tumor cells in other lymphatic organs travel (metastasize) to nearby lymph nodes or other tissues.

Visit our hub to learn more about types of cancer and treatments.

What are conditions that affect the lymphatic system?

Conditions affecting the lymphatic system are generally the result of infection, disease, or damage to the lymphatic system.

The most common conditions affecting the lymphatic system are:

  • Tonsillitis: This is inflammation in the tonsils in the throat. In some cases of severe swelling, a surgeon needs to remove your tonsils. Tonsillitis is typically due to a bacterial or viral infection. Strep throat is a common bacterial cause. Tonsillitis is most common in children.
  • Glandular fever: Glandular fever, also known as mononucleosis, is most common in teenagers and young adults and is often the result of the Epstein-Barr virus. It usually gets better on its own, but in some cases, it can cause extreme tiredness for a few months. Glandular fever can cause the spleen to swell. For this reason, doctors recommend avoiding strenuous activity or heavy lifting if you have glandular fever.
  • Crohn’s disease: Crohn’s disease is an inflammatory bowel disease that frequently occurs in the small intestine and colon. The lymphatic system plays a role in immune system regulation of the intestinal tract because lymphatic vessels are highly permeable to bacteria.
  • Appendicitis: Appendicitis is inflammation of the appendix. It is commonly due to blockages, infection in the digestive tract, or inflammatory bowel disease. The most common symptom is pain in the abdomen. Appendicitis is a medical emergency that requires immediate surgical removal of the appendix.
  • Hodgkin disease: Hodgkin disease is a type of cancer that develops in the lymphatic system. The cause is unknown, but certain factors place you at a higher risk of developing Hodgkin disease. These factors include being in early or late adulthood, being male, having had a past Epstein-Barr virus infection, and having a parent or sibling with Hodgkin disease.


The lymphatic system plays an important role in the body’s immune response and defense system.

The major parts of the lymphatic system are the spleen, tonsils, thymus gland, bone marrow, and appendix. Each part plays a different role.

When the lymphatic system is not functioning properly, infection or cancer can occur. Some cancers start in the lymphatic system or spread to it from their primary site of origin.

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Medical Reviewer: Stacy Sampson, D.O.
Last Review Date: 2022 May 30
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