The Lymphatic System

What Does The Lymphatic System Do?

The lymphatic system has three main purposes:

  1. It removes excess fluid and waste products from the spaces between the cells and returns them to the blood stream.

  2. It aids the immune system in destroying and removing waste, debris, dead blood cells, pathogens, toxins, and cancer cells.

  3. It absorbs fats and fat-soluble vitamins from the digestive system and delivers these nutrients to be used by the cells of the body.

Lymphatic System

What Makes Up The Lymphatic System?

Lymph leaves the area of the cells through lymph capillaries, which merge together into larger lymphatic vessels that carry lymph throughout the body.

5 Interesting Facts About The Lymphatic System

  1. There are over 500 lymph nodes throughout the body, with the majority of them being located in the neck, groin and armpits.

  2. Lymph is a mixture of about 90% water and 10% solutes such as proteins, cellular waste products, dissolved gases, and hormones.

  3. The lymphatic system returns about 3.17 quarts (3 liters) of fluid each day from the tissues to the circulatory system.

  4. One way that lymph moves is via the squeezing action of the skeletal muscles surrounding the lymph vessels.

  5. On average, at any time about I to 2 quarts of lymph fluid circulates in the lymphatics and body tissues.

Since the lymphatic system does not have a heart to pump it, its upward movement depends on the motions of the muscle and joint pumps as well as the movement of the diaphragm when we breathe.

The lymph passes through Lymph nodes, which are round or kidney-shaped, and, while usually smaller, can be up to one inch in diameter. Most of the lymph nodes are found in clusters in the neck, armpit, and groin area. Nodes are also located along the lymphatic pathways in the chest, abdomen, and pelvis.

All of the lymphatic vessels of the body carry lymph toward the two lymphatic ducts: The thoracic duct connects the lymphatic vessels of the legs, abdomen, left arm, and the left side of the head, neck, and thorax to the left brachiocephalic vein. The right lymphatic duct connects the lymphatic vessels of the right arm and the right side of the head, neck, and thorax to the right brachiocephalic vein.

Outside of the system of lymphatic vessels and lymph nodes, there are masses of lymphatic tissue known as lymphatic nodules. They work to protect the body from pathogens entering the body through open body cavities. The most prominent of these are Tonsils and Adenoids and Peyer’s Patches. Peyer’s Patches are small masses of lymphatic tissue found in the small intestine. Peyer’s patches contain T and B cells that monitor the contents of the intestinal lumen for pathogens. Once the antigens of a pathogen are detected, the T and B cells spread and prepare the body to fight a possible infection.

The lymph system also includes the spleen, thymus and bone marrow.

The Spleen is a flattened, oval-shaped organ located in the upper left quadrant of the abdomen lateral to the stomach. The spleen contains lymphocytes and another kind of white blood cell called macrophages, which engulf and destroy bacteria, dead tissue, and foreign matter and remove them from the blood passing through the spleen

The Thymus produces and trains T cells during fetal development and childhood. By the time a person reaches puberty, the immune system is mature and the role of the thymus is diminished. After puberty, the inactive thymus is slowly replaced by adipose (fat) tissue.

Red bone marrow is mostly found in the ends of long bones and in the flat bones of the body. It contains many stem cells that produce blood cells. All of the leukocytes, or white blood cells, of the immune system are produced by red bone marrow.

How Does The Lymphatic System Work?

Fluid Removal

Arterial blood carries oxygen, nutrients, and hormones for the cells. To reach these cells it leaves the small arteries and flows into the tissues. This fluid is then known as interstitial fluid and it delivers its nourishing products to the cells. Then it leaves the cell and removes waste products.

After this task is complete, 90% of this fluid returns to the circulatory system as venous blood.

The remaining 10% of the fluid that stays behind in the tissues as a clear to yellowish fluid known as lymph.

The lymph is moved through the body in its own vessels making a one-way journey from the interstitial spaces to the subclavian veins at the base of the neck.

As it moves upward toward the neck the lymph passes through lymph nodes which filter it to remove debris and pathogens.

The cleansed lymph continues to travel in only one direction, which is upward toward the neck.

At the base of the neck, the cleansed lymph flows into the subclavian veins on either side of the neck.

Assist The Immune System

There are between 500-600 lymph nodes present in the average human body. It is the role of these nodes to filter the lymph before it can be returned to the circulatory system.

Lymphatic vessels carry unfiltered lymph into the node. There waste products, and some of the fluid, are filtered out.

In another section of the node, lymphocytes, which are specialized white blood cells, kill any pathogens that may be present. This causes the swelling commonly known as swollen glands.

Lymph nodes also trap and destroy cancer cells to slow the spread of the cancer until they are overwhelmed by it.

Lymphatic vessels carry the filtered lymph out of the node so that it can continue its return to the circulatory system.

Assist The Digestive System

Another major function of the lymphatic system is the transportation of fatty acids from the digestive system. The digestive system breaks large macromolecules of carbohydrates, proteins, and lipids into smaller nutrients that can be absorbed through the villi of the intestinal wall. Most of these nutrients are absorbed directly into the bloodstream, but most fatty acids, the building blocks of fats, are absorbed through the lymphatic system.

In the villi of the small intestine are lymphatic capillaries called lacteals. Lacteals are able to absorb fatty acids from the intestinal epithelium and transport them along with lymph. The fatty acids turn the lymph into a white, milky substance called chyle. Chyle is transported through lymphatic vessels to the thoracic duct where it enters the bloodstream and travels to the liver to be metabolized.

What Can Go Wrong With Your Lymphatic System?

These are some potential problems that can occur in your lymphatic system:


This is a condition where the lymph nodes become swollen or enlarged, usually because of a nearby infection. Swollen lymph nodes in the neck, for example, can be caused by a throat infection. Once the infection is treated, the swelling usually goes away. If several lymph node groups throughout the body are swollen, that can indicate a more serious disease that needs further investigation by a doctor.


Also called adenitis, this inflammation of the lymph node is caused by an infection of the tissue in the node. The infection can cause the skin overlying the lymph node to swell, redden, and feel warm and tender to the touch. This infection usually affects the lymph nodes in the neck, and it’s usually caused by a bacterial infection that can be easily treated with an antibiotic.


These cancers start in the lymph nodes when lymphocytes undergo changes and start to multiply out of control. The lymph nodes swell, and the cancer cells crowd out healthy cells and may cause tumors (solid growths) in other parts of the body.

Splenomegaly (enlarged spleen)

In healthy people, the spleen is usually small enough that it can’t be felt when you press on the abdomen. But certain diseases can cause the spleen to swell to several times its normal size. Usually, this is due to a viral infection, such as mononucleosis. But in some cases, more serious diseases such as cancer can cause it to expand..


Tonsillitis is caused by an infection of the tonsils. When the tonsils are infected, they become swollen and inflamed, and can cause a sore throat, fever, and difficulty swallowing. The infection can also spread to the throat and surrounding areas, causing pain and inflammation. A child with repeated tonsil infections may need to have them removed (a tonsillectomy).

How Do Your Keep Your Lymphatic System Healthy?

To keep your Lymphatic System healthy, follow these 3 rules:

  1. Breathe deeply. In the trunk, the diaphragm pushes down into the abdomen when you breathe in. This increased abdominal pressure pushes lymph into the less pressurized thorax.

  2. Get moving. Exercise also ensures the lymph system flows properly because contracting muscles also help to move the lumph.

  3. Drink plenty of water. Without adequate water, lymph fluid cannot flow properly.

This article is part of a series called “Your Body: An Owner’s Manual” which explains how your body systems work and how to maintain them. The first article in the series included a picture of my wife, fitness coach Kathie Lamir, who exemplifies a healthy body. Pictures of Kathie were so well received that I have included one with each article in the series

Fitness Coach Kathie Lamir

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