This is how the lymphatic system works

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Last Medical Review: March 28, 2020
Medically Reviewed by Dr. Elisabeth Vincent Hamelin

The lymphatic system consists of a network of lymph vessels that carry lymph. It also consists of various organs, such as the spleen and the gut. The lymphatic system is needed for the body to feel good. It is important for the fluid balance in the body and for the body’s defense against infections.

Tasks of the lymphatic system

These are the most important tasks of the lymphatic system:

  • The lymphatic system maintains the fluid balance in the body along with the blood system. This is done by transporting excess fluid from different parts of the body. This fluid is called lymph.
  • The lymphatic system participates in the body’s defense against bacteria, viruses and cancer.

Different parts of the lymphatic system

The lymphatic system consists of several parts:

  • lymph, a fluid found in the body
  • lymphatic vessels transporting the lymph
  • lymph nodes or lymph nodes that absorb part of the lymph, take care of and destroy bacteria, viruses and other things that can be harmful to the body
  • spleen
  • thymus
  • other lymphatic tissue, such as the tonsils.


Between the cells of the body in the tissues there is a transparent tissue fluid. The fluid is squeezed into the tissues of very thin blood vessels, capillaries. In this way, oxygen and nutrition come out to the cells in the body. The cells then release carbon dioxide and waste into the liquid surrounding the cell. This is called cell respiration.

The lymphatic system sucks up the tissue fluid, which forms the lymph

The lymphatic system then sucks up the fluid that is left over and forms lymph. The lymph consists of water, proteins, white blood cells, fatty acids, bacteria and old and damaged cells. The lymph may also contain other things such as color from tattoos. Eventually, these substances are returned to the bloodstream again.

The lymph vessels transport the lymph

It is the lymph vessels that carry the lymph in the body. The fluid is transported by the lymph vessels being compressed by the movements of the body.

The small lymph vessels

The smallest lymph vessels are called lymph capillaries. They have very thin walls that can be opened. This is so that the lymph vessels can easily absorb fluid from the surrounding tissue. The lymph capillaries start out in the tissues between the cells. The small lymph vessels then merge with other small lymph vessels and form larger vessels. The larger the vessel, the thicker the walls.

The larger lymphatic vessels

The larger vessels of the lymphatic system carry lymph in the direction of the chest. The lymphatic vessels pass through several lymph nodes on the way to the chest. In the larger lymph vessels there are flaps for the lymph to be transported in the right direction. Between the flaps are so-called lymph hearts. These contract and relax and thus the lymph is pumped further into the vessel. This movement is slow when you rest and increases during body movements such as when exercising. Another word for lymph hearts is lymphangioma.

The lymph is emptied into the venous system close to the heart

The larger lymph vessels gather together into a larger bundle that goes up through the chest. At the height of the clavicle, the lymph is emptied into a vein and mixed with the blood. Lymph from the entire lower body and from the left upper body half empties back into the bloodstream at the height of the left clavicle. Lymph from the upper right half of the body is emptied in height with the right clavicle.

It happens that the lymphatic system is damaged. You can also have congenital damage to the lymphatic system, although it is unusual. Then the transport and uptake of lymph fluid can be impaired and a swelling is formed. It’s called lymphedema.

lymph nodes

The lymph vessels transport the lymph through so-called lymph nodes. The lymph nodes are often gathered in groups, such as beads on a necklace, for example in the armpits, neck, at the jaws, groin, behind the sternum and along the large blood vessels in the stomach. The lymph nodes can also be scattered one by one in the body. There are between 500 and 1000 lymph nodes in the body. Lymph nodes are also called lymph nodes as they do not really function as glands.

The lymph nodes can swell when you have an infection

The lymph nodes are usually swollen if you have an infection. Then you can feel them as elongated, slightly tender lumps under the skin. The fact that the lymph nodes swell is due to the fact that they are working to activate the immune system.

In the lymph nodes are white blood cells

The lymph nodes have lymphocytes. The lymphocytes are a type of white blood cell. They defend the body against bacteria and other microorganisms. The lymph nodes also contain plasma cells, which form so-called antibodies. The antibodies also participate in the immune system. Lymphocytes and plasma cells are mixed into the lymph as the lymph passes through the lymph node.

Bacteria are destroyed in the lymph nodes

The lymph nodes cleanse the lymph from harmful substances. Several small lymph vessels transport lymph to the lymph node. When the lymph passes through the lymph node, bacteria and other foreign particles that the lymph carries with it are destroyed. Sometimes, tumor cells that have entered the lymph fluid can also be destroyed in the lymph nodes. Some of the lymph fluid is also absorbed by the lymph node. This means that the amount of lymph that is passed on decreases and thickens. The purified lymph then leaves the lymph node and proceeds into the lymphatic system.


The spleen is the body’s largest lymphatic organ. It is located high in the stomach on the left side. It is protected by the lower ribs. The spleen is about twelve inches long. It is surrounded by a protective capsule of connective tissue. The spleen also contains blood-filled cavities. Both blood vessels and lymph vessels pass in and out of the spleen.

Information of the spleen

These are the tasks of the spleen:

  • It participates in the body’s defense against infections.
  • It breaks down old or damaged red blood cells.
  • It acts as a storehouse for red blood cells.
  • It forms blood cells during the fetal stage.

The spleen’s defense against infections proceeds in much the same way as in the lymph nodes. The spleen contains lymphocytes. It’s a kind of white blood cell. In the spleen there are also so-called plasma cells and cells capable of eating invading cells. Bacteria and other foreign particles are destroyed by these.


The bristles are also a lymphatic organ. It lies behind the sternum adjacent to the heart and is surrounded by a capsule of connective tissue. The bouts are important for the development of the immune system in young children. After puberty, it decreases in size and activity. Therefore, it is larger in small children, but small in an adult. The thymus is also called thymus.

T-lymphocytes mature in the gut

In the glands, a type of white blood cell called T lymphocytes matures. They participate in the immune system when they eventually reach the bloodstream. T lymphocytes are transformed into so-called killer cells when they come into contact with foreign microorganisms, such as bacteria. Killer cells can destroy the microorganisms.

Other parts of the lymphatic system

The lymphatic system contains more parts than lymphatic vessels, lymph nodes, the spleen and the glands. In the throat are the tonsils which are also included in the lymphatic system. The neck tonsils together form a ring that protects the entrances to the respiratory tract and the digestive tract. In the walls of the intestines and in tissues around the intestine there are also so-called lymphatic tissues that participate in the body’s immune system.

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