What is the spleen?
The spleen (splen, lien) is the largest lymphoid organ in the human body. It houses one third of the total lymphoid tissue. Unlike the lymph nodes, however, it is not involved in the lymphatic circulation, but in the blood circulation.
The coffee bean-shaped organ is approximately thirteen centimeters long, eight centimeters wide, and three to four centimeters high. When empty of blood, it weighs about 160 grams.
The spleen is surrounded by a thin, tight, mesh-like connective tissue capsule. Numerous tissue bars (trabeculae) extend from this capsule into the interior of the organ. This creates a three-dimensional bar that surrounds the actual splenic tissue (pulp).
Red and white pulp
The cut surface of a fresh spleen shows an extensive dark red tissue, the red pulp. Interspersed with the red pulp is the white pulp. These can be seen as pinhead-sized white specks scattered throughout the red pulp.
The white pulp consists of lymphatic tissue. This spreads along the arterial vessels and forms the so-called periarterial lymphatic sheaths (PALS) and spherical lymph follicles. The white pulp accounts for about 15 percent of the total organ volume.
Splenic artery and vein
The organ is supplied with blood by the splenic artery (lienal artery, splenic artery). This branches into small and minute blood vessels that carry blood through the tissues. The blood flows out of the organ again via fine venous vessels that finally unite to form the lienal vein (splenic vein).
The splenic hilus is that point on the organ where the lienal artery enters and the lienal vein exits.
Ancillary spleens
Most people have only one spleen. About one in five people have an additional one or even more. They are called accessory spleens or secondary spleens and are smaller than the main organ.
Not a vital organ
Such an operation is necessary, for example, if the organ tears or ruptures completely (rupture) when injured in the abdominal cavity. Because it is so well supplied with blood, this rupture can lead to life-threatening bleeding and shock.
Splenectomy can have one drawback, however: Sufferers are often more susceptible to infections and blood poisoning (sepsis) and have an increased risk of severe disease progression if infected with certain bacteria. Those affected therefore receive preventive vaccinations against Streptococcus pneumoniae (common causative agent of pneumonia), Haemophilus influenzae (responsible for various diseases) and meningococci (causative agent of meningitis).
What is the function of the spleen?
Read more about the various functions of the organ, such as immune defense and blood storage, in the article Spleen Function.
Where is the spleen located?
The stomach and large intestine are found in the immediate vicinity. Both organs are connected to the spleen and diaphragm by ligaments.
The exact location of the organ depends on breathing, body position, the filling state of neighboring organs and the shape of the chest.
What problems can the spleen cause?
A diseased spleen is often enlarged (splenomegaly) and then palpable below the left costal arch (it cannot be palpated in a healthy state). It itself and surrounding tissues may be tender to pressure, indicating a diseased condition.
Major diseases of the spleen include:
- Splenomegaly: usually caused by infection or leukemia. It can result in both hypo- and hypersplenism.
- Splenic congestion: blood stasis in the organ caused by liver cirrhosis or right heart failure.
- Inflammation of the organ
- Hyposplenia (Hyposplenisums): Underfunction of the organ; has an effect on the immune system, especially in children and adolescents
- Asplenia: lack of organ function – in the case of congenital or acquired (splenectomy) absence of the organ or total loss of the organ (in various diseases)
- Hypersplenism: hyperfunction of the organ: increased breakdown of blood cells, usually associated with splenomegaly and a lack of blood cells in the body
- Splenic cysts: fluid-filled capsules on or in the organ
- Splenic abscess: pus-filled cavity on or in the organ
- Splenic rupture: rupture of the spleen due to blunt trauma (such as after an accident). It can lead to life-threatening massive bleeding into the abdominal cavity.
