Synonyms in a broader sense
Medical: splenic fever, ruptured spleen, immune defence, thrombocytes, blood platelets
Anatomy of the spleen
The spleen is an organ that is located in the abdominal cavity (abdomen) and performs various functions. It is about the size of a kidney and nestles in the left upper abdomen against the diaphragm (diaphragm), the stomach and the left kidney. The average size of the spleen is 4x7x11 cm.
Thus wedged between other organs, its shape is often compared to that of an orange segment. Since the spleen is so close to the diaphragm, it moves with the breathing, but at normal size it is mostly covered by the ribs and thus not palpable from the outside. On the one hand, it acts as a filter station in the bloodstream and on the other hand, it plays an important role in the body’s defense against “intruders”, i.e. the spleen is part of the immune system.
Furthermore, it is a part of the lymphatic system. These different functions can also be seen in the color. The blood filter of the spleen is red and the area that is responsible for the defense appears white (red pulp and white pulp).
The organ is made of a very soft material (pulp) and only gets a little stability from a thin capsule (and fibers that are drawn from the capsule to the inside). It is very important for the blood filter function of the spleen that a large artery delivers blood and an equally large vein (artery) removes the blood. One can imagine the spleen as a sponge into which the blood is pressed.
The red blood cells (erythrocytes), which are still young and flexible, can slip through the meshes of the sponge, whereas the old ones (usually around 120 days old) get stuck in it and are broken down. The defensive function of the spleen can be described as a parking lot or collection point for white blood cells (leukocytes). The white blood cells do not float continuously in the bloodstream, but accumulate at different stations in the body, for example in the spleen.
In contrast to the lymph nodes, which are a filter station for a certain region of the body, the spleen is a filter station for the entire bloodstream. The white pulp, which is responsible for defence, is grouped around the vessels as a lymph sheath (vagina periarterialis lymphatica) and as splenic nodules (Malphigi corpuscles). The white blood cells that play the greatest role in the spleen’s defense system are the so-called lymphocytes.
They wait in the white pulp in order to be able to react to pathogens that have flushed past or to re-enter the bloodstream after a certain time and patrol the bloodstream. Thus the spleen has a special role in blood poisoning, in which bacteria multiply in the blood. New lymphocytes can also be formed in the white pulp of the spleen.
Although the spleen has important functions, it is not an organ essential for survival. For example, if it is injured in an accident and bursts because of the thin capsule (rupture of the spleen), it must be removed because of the strong blood circulation. The tasks of the spleen are then taken over by the liver and other organs, whereby one can be more susceptible to infections.
Especially in children whose immune system against pathogens is not yet fully developed, the spleen would not be removed lightly. After a splenectomy, one must be vaccinated against certain diseases or certain pathogens, for example meningitis and pneumonia. The pathogens responsible for this are the so-called pneumococci, menigococci and Haemophilus influenzae.
