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The Human Spleen

The spleen is the largest lymphatic organ in the lymphatic system and is involved in the production and removal of blood cells. The spleen is located in the upper left region of the abdominal cavity, just behind the stomach and is protected by the 9th and 11th ribs. The spleen is a soft oval shaped organ and is purple in colour. A human spleen is approximately  5 inches long x 3 inches wide and 1 ½ inches thick.  A healthy adult will have a spleen that weights approx. 6 oz.

Anatomy of the Spleen

The spleen is rich with blood, the blood is supplied by the splenic artery and exits through the splenic vein. The splenic artery branches off from the aorta and the celiac ruck to deliver oxygenated blood to the spleen. The splenic vein carries deoxygenated blood way from the spleen. The spleen consists of lymphatic vessels that help transport lymph away from the spleen. Lymph is a clear fluid that comes from blood plasma that exits the blood vessels at capillary beds. The outer tissue that is covering the spleen is called a capsule.  The spleen is divided into 4 smaller sections which are called lobules.

Spleen Anatomy Illustration. TTSZ/iStock/Getty Images Plus 

The spleen consists of 2 types of tissues:

  Red Pulp Tissue: Consists of sinuses (cavities that are filled with blood) and splenic cords (connective tissues containing red blood cells and some white blood cells (lymphocytes and macrophages))

  • Filters the blood and helps to destroy old damaged red blood cells.
  • Recycles the iron and protein components of hemoglobin

White Pulp Tissue:

Made of lymphatic tissue that destroys pathogens in the blood & produces antibodies.

  • Is lymphatic tissue and consists of lymphocytes called B lymphocytes and T lymphocytes.
  • Surrounds the arteries.
  •  Immune cells – helps fight infection.

    “The spleen contains two different tissues, white pulp (A) and red pulp (B). The white pulp functions in producing and growing immune and blood cells. The red pulp functions in filtering blood of antigens, microorganisms, and defective or worn-out red blood cells.”

What Does the Spleen Do?

1.  Filter’s Blood

The spleens main function is to act as a filter for your blood. It recognizes and removes blood that has damaged cells, pathogens such as viruses and bacteria. Red blood cells must pass through a maze of narrow passages within the spleen; the healthy blood cells will pass through but blood cells that are pathogenic will be broken down by macrophages. Macrophages are large white blood cells that destroy unhealthy blood cells and help reduce inflammation.

The spleen will save the useful components from the old blood cells such as iron in the form of ferritin and bilirubin and eventually returns the iron back to your bone marrow where hemoglobin is made.

2.  Stores Blood.

 The spleen can hold up to 1 cup of reserve blood in your spleen.  The spleen can release stored blood into circulation to replace blood that was lost during trauma/injury to the body. The spleen also stores red blood cells and platelets, platelets help to form blood clots which prevent further blood loss. The vessels in the spleen are able to get wider or narrower depending on your body’s needs. When extreme bleeding occurs due to injury the red blood cells and platelets are released from the spleen. The Macrophages are also released and they help to reduce inflammation & also help to destroy pathogens to the injured area. If trauma occurs and you lose blood, your spleen responds by releasing reserved blood back into your system. 

3. Immune System

The spleen develops and produces mature immune cells that are capable of identifying and destroying pathogens in the blood. These immune system cells are called Lymphocytes.

Lymphocytes: White blood cells that protect the body against foreign organisms that infect the body.

T Lymphocytes – immune response which activates certain immune cells to fight infection. They are derived from the thymus and travel to the spleen through blood vessels. B Lymphocytes – are found in bone marrow stem cells. They create antibodies that are specific to an antigen. The BL binds to the antigen and “marks” it for destruction by other immune cells.

Can you Live Without your Spleen?

Yes you can! Although the spleen is a very important organ in the human body, the spleen can be removed if necessary. Some people may need to have their spleen removed to prevent internal bleeding that could occur due to an injury, or to treat illness etc.  An enlarged spleen may occur due to bacterial/viral infection, increased splenic vein pressure, vein blockage and cancer. The spleen can rupture, which causes serious internal bleeding and can become fatal.

Splenectomy: surgery to remove your spleen.

Illnesses that can put your spleen at risk:

-          Sickle Cell Anemia ( irregularly shaped red blood cells)

-          Mononucleosis

-          Low Platelet count

-          Cancer

What happens if you don’t have a spleen?

If you have to have your spleen removed it will not regenerate but the liver, lymph nodes and bone marrow will step in to perform the filtration functions that the spleen previously did. Patients who have had their spleen removed will be more vulnerable to infections as their body will have a much lower amount of antibodies to help fight off infections. Antibiotics are also recommended for patients as well. Children who have had their spleen removed are recommended to be on a protocol of antibiotics.



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