Spleen

The spleen ( lien Latin, Greek σπλήν SPLEN ) is a switched into the bloodstream organ of the lymphatic system and is located in the abdomen near the stomach. The spleen has three basic tasks. First, it serves to increase the white blood cells belonging to the lymphocyte and, therefore, plays a role in the defense against foreign substances ( antigens). Second, it is an important location for the counting of white blood monocytes also. Third, it serves the separation of outdated red blood cells. In the late fetal development and in children beyond the spleen plays a role in the formation of red blood cells.

Anatomy

The spleen is in man an approximately 11 × 7 × 4 cm large organ ( mass 150-200 grams), located in the left upper abdomen below the diaphragm and above the left kidney. In mammals, the spleen can occupy significant proportions, the horse she is 50 cm long. In birds, the spleen is spherical. It is the largest organ of mesodermal origin lymphoreticular, which is divided into segments.

In humans, a distinction is concave visceral surface ( visceral surface ) and the convex diaphragmatic surface ( diaphragmatic surface ). Separately, these surfaces through the dorsal blunt edge ( Margo inferior obtusus ) and the ventral, sharp, often notched edge ( Margo superior acutus ). On the visceral surface is the hilum - a usually V- shaped structure, move through the blood vessels and nerves. From the hilum the anterior abdominal skin fold ( ligament gastrolienale ) draws on the greater curvature of the stomach, as well as the posterior abdominal skin fold ( ligament phrenicolienale ) the diaphragm.

The spleen is surrounded by a connective tissue, covered by peritoneal epithelium capsule from which a bälkchenartiges ( trabecular ) connective tissue and some smooth muscle cells in the parenchyma of the splenic pulp ( pulp from the Latin " pasty mass " ) radiate. It is therefore intraperitoneally.

The spleen combines two organs in construction and structure. The white pulp as an internal organ takes over as lymphatic organ immunological purposes. The red pulp removes harmful particles from the blood by their phagocytes ( macrophages ). It also stores white blood cells and platelets, which can distribute them.

The dichtmaschige reticulum contains the macroscopically whitish and in their entirety as white pulp (pulp alba) designated Milzknötchen, also known as Malpighian corpuscles. It involves lymph follicles, consisting of lymphoid tissue B lymphocytes. In addition, part of the white pulp which are arranged around the vessels periarterial lymphatic sheaths ( PALS ) of T lymphocytes.

The space between the nodules is completed by a wide-meshed reticulum, the flows through the blood and as the red pulp (pulp rubra) is referred to. In her aged red blood cells ( erythrocytes) are degraded by squeeze through the narrow connective tissue network of Milzstränge. Old red blood cells are not as easily formed as young and caught in the mesh. Finally, they are eliminated by macrophages. In the areas located under the splenic capsule of the red pulp monocytes are stored in larger cell clusters.

The blood supply is via the splenic artery entering at the hilus. They branched into trabeculae and trabecular arteries, revealing the opening into the center of the Milzfollikel central arteries. The splenic vein (also splenic vein ) carries blood from the portal vein ( portal vein ).

Accessory spleens

In some individuals exist alongside the " Hauptmilz " one or more accessory spleens ( Splen accessory ). These are small nodular organs from spleen tissue, with the same fine structure and function. This comes at 5-30 % before examined people. They are usually located near the Milzpforte ( hilum splenicum ), the tail of the pancreas, in the ligamentum gastrosplenic ( band between the stomach and spleen) or in the large network.

Clinically relevant they are, when due to a disease, surgical removal of the spleen ( splenectomy ) is needed, because the disease disappears before all the spleens were removed.

The main functions of the spleen

In the spleen, are over-aged and changed in their deformability or membrane enzyme defects or damaged blood cells, especially red blood cells (RBCs ) and platelets (thrombocytes) receptors and degraded by macrophages., Cells that are loaded with antibody, microorganisms, immune complexes, fibrin, and other colloidal particles are separated in this way.

As part of the immune system, the antigen -induced proliferation and differentiation of B and T lymphocytes takes place in the spleen.

In fetuses and children up to the age of six, the spleen is significantly involved in the formation of red blood cells. In diseases of the hematopoietic bone marrow, the spleen can become a blood-forming organ in old age again.

Study possibilities of spleen

The spleen is palpable only with significant enlargement below the left costal margin. As imaging techniques are ultrasound, computed tomography (CT, see Tigermilz ) and magnetic resonance imaging (NMR, MRI ) are used. With angiography, the splenic vessels can be displayed. A biopsy of the spleen to Gewebsuntersuchung is unusual and dangerous because the spleen is a well- perfused organ.

Diseases of the spleen

The spleen is an organ that causes problems rarely. A dangerous situation is the Milzverletzung with splenic rupture during blunt abdominal trauma, gunshot or stab wounds or broken ribs on the left, as there is a possibility of hemorrhage into the abdominal cavity.

Other conditions are:

• Milzentzündung ( Splenitis )
• Spleen ( splenomegaly): An enlarged spleen can have many causes. Among others, it can be (e.g., Epstein -Barr virus infection), a sign of a leukemia, a malaria infection or a viral disease.
• Splenic tumors and Milzmetastasen
• Splenic infarction
• Amyloidosis of lymphoid follicles ( Sagomilz )
• Postsplenektomie syndrome ( OPSI syndrome, overwhelming postsplenectomy infection): septic disease after removal of the spleen ( splenectomy )

In people with inoperable or missing ( asplenia ) spleen is an immune deficiency especially for bekapselte bacteria (eg, Haemophilus influenzae B, pneumococcus ). For these people there is rarely a OPSI syndrome, that is, a rapidly-progressing bacterial infection and sepsis with high mortality.