What’s the Largest Lymphatic Organ?

Written by Rob Amend
Published: May 11, 2023
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The Largest Lymphatic Organ: Introduction

The human body is a wonderful collection of organs and systems, including the lymphatic system. This article will identify and discuss the largest organ in that system.

What Is an Organ?

The heart: an organ in the circulatory system.

The heart is an organ in the circulatory system.

©Explode/Shutterstock.com

When identifying the largest lymphatic organ, we must first look at what we mean by organ. The term ‘organ‘ is a biological one referring to a collection of tissues that performs a function in a living organism. The work done by these organs is responsible for sustaining life. More complex animals—those considered “higher”—have groups of organs that form systems. Animals considered higher have more organ systems than less complex species, including the skeletal, muscular, nervous, digestive, respiratory, circulatory, and reproductive systems. The lymphatic system is a part of the larger circulatory system.

What Is the Lymphatic System?

Lymph nodes are organs in the lymphatic system.

Lymph nodes are organs in the lymphatic system, but not the largest.

©Tinydevil/Shutterstock.com

The lymphatic system is a collection of organs, tissues, and vessels that balance bodily fluids. As blood circulates through the body, some passes through the sides of capillaries into the surrounding tissue. The lymphatic system collects this lost fluid (called lymph once it is within the lymphatic system), cleans it, and returns it to the circulatory system through lymphatic vessels.

The lymphatic system also assists in immunity by producing white blood cells called lymphocytes. The body creates two types of lymphocytes: T lymphocytes (T cells) and B lymphocytes (B cells.) Although lymphocytes can be found throughout the body, they are primarily found in the body’s lymphatic organs.

The major primary organs in the lymphatic system are the thymus and bone marrow. The secondary lymphoid organs include the spleen, lymph nodes, tonsils, and the appendix.

The Largest Lymphatic Organ: The Spleen

The spleen (shown here in cross-section with staining) is the largest organ in the lymphatic system.

The spleen (shown here in cross-section with staining) is the largest organ in the lymphatic system.

©micro.journey/Shutterstock.com

Although a secondary organ, the spleen is the largest organ in the lymphatic system. Its length and width are about 5 by 3 inches, it is 1.5 inches thick, and it weighs about 6 ounces. It filters blood by releasing lymphocytes that destroy harmful microscopic organisms and irritants. It also holds some blood in reserve, which can be pumped into the circulatory system in an emergency, like hemorrhaging. This is one reason that a damaged spleen can be life-threatening.

Though the lymphatic system is not a popularly understood organic system, it plays a vital part in the body’s function. Consequently, besides being the largest lymphatic organ, the spleen is crucial in blood filtration, storage, and circulatory function.

The photo featured at the top of this post is © greenbutterfly/Shutterstock.com


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About the Author

Rob Amend is a writer at A-Z Animals, primarily covering meteorology, geology, geography, and animal oddities. He attained a Master's Degree in Library Science in 2000 and served as reference librarian in an urban public library for 22 years. Rob lives in Cincinnati, Ohio, and enjoys spending time with his family, hiking, photography, woodworking, listening to classic rock, and watching classic films—his favorite animal is a six-foot-tall rabbit named Harvey.

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