Dictionary:

spleen

  (splēn)

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1. 1. A large, highly vascular lymphoid organ, lying in the human body to the left of the stomach below the diaphragm, serving to store blood, disintegrate old blood cells, filter foreign substances from the blood, and produce lymphocytes.
   2. A homologous organ or tissue in other vertebrates.
2. Obsolete. This organ conceived as the seat of emotions or passions.
3. Ill temper: vent one's spleen.
4. Archaic. Melancholy.
5. Obsolete. A whim; a caprice.

[Middle English splen, from Old French esplen, from Latin splēn, from Greek.]

An organ of the circulatory system present in most vertebrates, lying in the abdominal cavity usually in close proximity to the left border of the stomach.

In humans the spleen normally measures about 1 by 3 by 5 in. (2.5 × 7.5 × 12.5 cm) and weighs less than ½ lb (230 g). It is a firm organ with an oval shape and is indented on its inner surface to form the hilum, or stalk of attachment to the peritoneum. This mesentery fold also carries the splenic artery and vein to the organ.

The spleen is an important part of the blood-forming, or hematopoietic, system; it is also one of the largest lymphoid organs in the body and as such is involved in the defenses against disease attributed to the reticuloendothelial system. Although the chief functions of the spleen appear to be the production of lymphocytes, the probable formation of antibodies, and the destruction of worn-out red blood cells, other less well-understood activities are known. For example, in some animals it may act as a reservoir for red blood cells, contracting from time to time to return these cells to the bloodstream as they are needed. In the fetus and sometimes in later life, the spleen may be a primary center for the formation of red blood cells. Another function of the spleen is its role in biligenesis. Because the spleen destroys erythrocytes, it is one of the sites where extrahepatic bilirubin is formed. See also Bilirubin; Spleen disorders.

The spleen was linked in past centuries to a variety of emotions, characteristics, or behaviours — usually spitefulness, bad temper, or melancholy, but also sometimes to general liveliness and explosive wit. In the seventeenth century Shakespeare provided many a quote, including the tag ‘spleeny Lutheran’. In the eighteenth century we have Addison's ‘touchy testy pleasant fellow’ with ‘so much Wit and Mirth and Spleen’, whilst less positively a ‘touch of the spleen’ was what we would now call psychosomatic illness. In the late nineteenth century the concept still survived in such whimsies as Gilbert's in Patience: ‘… a sentimental passion of a vegetable fashion must excite your languid spleen’. And ‘venting one's spleen’ has traditionally described a vituperative outburst.

There seems no good reason why the spleen should have deserved these associations — unlike, say, the heart which manifests its link with love by an increase in beating rate with excitement. The spleen is physiologically and anatomically unobtrusive. It is in fact — unusually in the body for an unpaired organ — dispensible. We can live without it because its functions can be taken over elsewhere. It is a small spongy purple mass in a fibrous capsule, tucked under the left side of the diaphragm (smaller than the liver which is tucked under the right side).

The spleen is in a way a poor relation among organs in that it is rarely in the public eye — not even on the butcher's counter. It is not susceptible to dramatic televisual imaging and it does not invite transplantation. It does however sometimes need to be removed: it can suffer hidden injury, for example in crushing or road traffic accidents, when its rupture can cause internal bleeding; other causes for splenectomy include some blood diseases.

Although we can do without it if necessary, the spleen does normally have important functions. In fetal life it is the site of red blood cell formation, until this is taken over by the bone marrow. It contributes to the immune system, forming antibodies and producing and storing masses of lymphocytes. It contains extensive channels and spaces (sinuses) where the blood flows slowly and where senescent red blood cells break down and are removed from the circulation. It therefore becomes enlarged in some infective, parasitic, and blood diseases.

The spleen acts to some extent as a blood reservoir, although this mechanism for increasing circulating blood volume is relatively minor and unimportant in humans compared with some other animals. The smooth muscle in its capsule is activated by the autonomic nervous system in conditions of ‘fight or flight’ or after blood loss, squirting a little extra blood into the circulation — which is perhaps the nearest physiological equivalent to the metaphoric ‘venting’.

— Sheila Jennett

See lymphatic system. See also blood; humours; immune system.

Gland near the stomach with main function of destroying ‘worn-out’ red blood cells and recycling the iron. As a food it is called melts; A 150-g portion of calf spleen is a rich source of iron, vitamins B₂, niacin, and C; a good source of vitamin A; contains 6 g of fat; supplies 150 kcal (630 kJ).

The most commonly injured organ within the abdomen. The spleen lies just below the 9th and 11th ribs, making it very susceptible to puncture by a fractured rib or a direct blow to the trunk. It can even be ruptured during a non-contact sport as a result of very strenuous activity, especially if it has become enlarged by a viral infection (in athletes, nearly 40 per cent of splenic ruptures are associated with glandular fever caused by a viral infection called infectious mononucleosis). This is one of several important reasons for resting during a fever.

The spleen has a number of functions, including removing worn out red blood cells and dealing with some types of foreign body. In order to carry out these functions, it is very well supplied with blood, making it quite soft and fragile. A rupture often results in torrential internal bleeding which is difficult to stop. If untreated, this can lead to a serious lowering of blood pressure and death. Sometimes bed rest is sufficient treatment, but often surgical removal is the only viable course of action. Abdominal injuries are often underestimated in sports, especially when young people with enormous reserves of enthusiasm are involved. Consequently, a ruptured spleen may go unnoticed and untreated until the injured person loses so much blood he or she suffers from potentially fatal shock. Abdominal injuries are very difficult to diagnose, but expert medical assistance should always be sought if a person is suffering from persistent abdominal discomfort after a blow or after extreme exertion.

noun

A tendency to become angry or irritable: irascibility, irascibleness, temper, temperament, tetchiness. Informal dander. Slang short fuse. Idioms: low boiling point. See feelings.

A soft, highly vascular, roughly ovoid organ situated between the stomach and the diaphragm in the left hypochondriac region of the body. It is considered part of the lymphatic system.

For more information on spleen, visit Britannica.com.

A large, highly vascularized organ situated beneath the stomach. It is part of the reticuloendothelial system producing white blood cells, and removing worn out red blood cells and some foreign bodies. It is the most commonly injured organ in the abdomen. Its position just below the ninth and eleventh ribs makes it very susceptible to puncture by a fractured rib or a direct blow to the trunk. It can even be ruptured during a non-contact sport as a result of very strenuous activity, especially if it has become enlarged during a viral infection. About 40% of sport-related splenic ruptures are associated with infectious mononucleosis, emphasizing the need to avoid strenuous activity during the febrile stage of an illness. A splenic rupture often results in massive internal bleeding, which can lead to a potentially fatal lowering of blood pressure. Usually, surgical removal of the spleen is the only viable course of action. Splenic ruptures can easily go unnoticed. Expert medical assistance should be sought whenever an athlete is suffering from persistent abdominal discomfort after a blow or extreme physical exertion.

An organ in the lymphatic system, in the upper left part of the abdomen, that filters out harmful substances from the blood. The spleen also produces white blood cells, removes worn-out red blood cells from circulation, and maintains a reserve blood supply for the body.

A large lymphoid organ usually situated in the cranial part of the abdominal cavity on the left of the stomach. The spleen contains the largest collection of reticuloendothelial cells in the body. In ruminants the spleen is located on the left lateral wall of the reticulum and under the last two ribs on the left side. Called also lien.

• accessory s. — a small mass of tissue, histologically and functionally identical with that composing the normal spleen but found elsewhere in the body.
• slaughter s. — see slaughter spleen.

Spleen
Spleen
Laparoscopic view of a horse's spleen (the purple and grey mottled organ)
Latin	splen, lien
Gray's	subject #278 1282
Artery	Splenic artery
Vein	Splenic vein
Nerve	Splenic plexus
Precursor	Mesenchyme of dorsal mesogastrium
MeSH	Spleen
Dorlands/Elsevier	s_19/12750780

The spleen is an organ located in the abdomen of the human body, where it functions in the destruction of old red blood cells and holding a small reservoir of blood. It is regarded as one of the centers of activity of the reticuloendothelial system (part of the immune system). Until recently, the purpose of the spleen was not known. It is increasingly recognized that its absence leads to a predisposition to certain infections.

Anatomy

The human spleen is located in the upper left part of the abdomen, behind the stomach and just below the diaphragm. In normal individuals this organ measures about 125 × 75 × 50 mm (5 × 3 × 2 inches) in size, with an average weight of 150 grams (5 oz).

The spleen is the largest organ derived from mesenchyme and lying in the mesentery. It consists of masses of lymphoid tissue of granular appearance located around fine terminal branches of veins and arteries. These vessels are connected by modified capillaries called splenic sinuses.

Approximately 10% of people have one or more accessory spleens. They may form near the hilum of the main spleen, the junction at which the splenic vessels enter and leave the organ.

There are several peritoneal ligaments that support the spleen^[1] (to understand their naming it helps to know that "lien" is an alternate root for "spleen")

• gastrolienal ligament (gastrosplenic) - connects stomach to spleen.
• lienorenal ligament (splenorenal) - connects spleen to kidney.
• phrenicocolic ligament - connects left colic flexure to the thoracic diaphragm. The middle connects to the spleen.

Cross sections of the spleen reveal a red soft surface which is divided into two types of pulp which correspond to the two most important functional roles of the spleen, summarized below:^[2]

Area	Composition	Function
red pulp	* "sinuses" (or "sinusoids") which are filled with blood * "splenic cords" of reticular fibers * "marginal zone" bordering on white pulp	Mechanical filtration. Removes unwanted materials from the blood, including senescent red blood cells.
white pulp	Composed of nodules, called Malpighian corpuscles. These are composed of: * "lymphoid follicles" (or "follicles"), rich in B-lymphocytes * "periarteriolar lymphoid sheaths" (PALS), rich in T-lymphocytes	Helps fight infections.

Other functions of the spleen are less prominent, especially in the healthy adult:

• Production of opsonins, properdin, and tuftsin.

• Creation of red blood cells. While the bone marrow is the primary site of hematopoeisis in the adult, up until the fifth month of gestation, the spleen has important hematopoietic functions. After birth, no significant hematopoietic function is left in the spleen except in some hematologic disorders: e.g. myelodysplastic syndrome, hemoglobinopathies.

• Storage of red blood cells and other formed elements. This is only valid for certain mammals, such as dogs and horses. In horses roughly 50% of the red blood cells are stored there. The red blood cells can be released when needed. In humans, however, the spleen does not function as a depository of red blood cells, but instead it stores platelets in case of an emergency .^[3] These animals also have large hearts in relation to their body size to accommodate the higher-viscosity blood that results. Some athletes have tried doping themselves with their own stored red blood cells to try to achieve the same effect, but the human heart is not equipped to handle the higher-viscosity blood.

Disorders

Enlargement of the spleen is known as splenomegaly. It may be caused by sarcoidosis, malaria, Infectious mononucleosis, bacterial endocarditis, leukemia, pernicious anaemia, Gaucher's disease, leishmaniasis, Hodgkin's disute splenomegaly includes a complete blood count with differential, platelet count, and reticulocyte and atypical lymphocyte counts to exclude hemolytic anemia and leukemia. Assessment of IgM antibodies to viral capsid antigen (a rising titer) is indicated to confirm Epstein-Barr virus or cytomegalovirus. Other infections should be excluded if these tests are negative.

Absence

The absence of a spleen predisposes to some septicaemia infections. Vaccination and antibiotic measures are discussed under asplenia.

• Some people congenitally completely lack a spleen, although this is rare.

• Sickle-cell disease can cause a functional asplenia (or autosplenectomy) by causing infarctions of the spleen during repeated sickle-cell crises.

• It may be removed surgically (known as a splenectomy), and indeed often is. For example, it may be removed following abdominal injuries with rupture and hemorrhage of the spleen, or in the treatment of certain blood diseases (Idiopathic thrombocytopenic purpura, hereditary spherocytosis, etc.), certain forms of lymphoma or for the removal of splenic tumours or cysts.

Etymology and cultural views

The word spleen comes from the Greek splēn. In Latin its name is lien.

In French, spleen refers to a state of pensive sadness or melancholy. It has been popularized by the poet Charles Baudelaire (1821-1867) but was already used before, in particular in the Romantic literature (18th century). The connection between spleen (the organ) and melancholy (the temperament) comes from the humoral medicine of the ancient Greeks. One of the humours (body fluid) was the black bile, secreted by the spleen organ and associated with melancholy. In contrast, the Talmud (tractate Berachoth 61b) refers to the spleen as the organ of laughter, possibly suggesting a link with the humoral view of the organ.

In German, the word "spleen", pronounced as in English, refers to a persisting somewhat eccentric (but not quite lunatic) idea or habit of a person; however the organ is called "Milz", (cognate with Old English milte).

In 19th century England, women in bad humour were said to be afflicted by the spleen, or the vapours of the spleen. In modern English, "to vent one's spleen" means to vent one's anger, e.g. by shouting, and can be applied to both males and females; similarly, the English term "splenetic" is used to describe a person in a foul mood.

In China, the spleen '脾 (pí)' counts as the seat of one's temperament and is thought to influence the individual's willpower. Analogous to "venting one's spleen", "發脾氣" is used as an expression for getting angry, although in the view of Traditional Chinese Medicine, the view of "脾" does not correspond to the anatomical "spleen".

See also

• marginal zone

Additional images

The celiac artery and its branches.	The celiac artery and its branches.	Horizontal disposition of the peritoneum in the upper part of the abdomen.	Transverse section through the middle of the first lumbar vertebra.
The duodenum and pancreas.	The visceral surface of the spleen.	Transverse section of the spleen, showing the trabecular tissue and the splenic vein and its tributaries.	Transverse section of the human spleen, showing the distribution of the splenic artery and its branches.
Section of the spleen, showing the termination of the small bloodvessels.	Back of lumbar region, showing surface markings for kidneys, ureters, and spleen.	Side of thorax, showing surface markings for bones, lungs (purple), pleura (blue), and spleen (green).	Lymphatic system

Footnotes

External links

• SUNY Figs 38:03-01 - "The visceral surface of the spleen."
• SUNY Anatomy Image 7881
• "spleen" from Encyclopedia Britannica Online

Immune system: Lymphatic system (Lymph, Lymphocytes)
Primary	Bone marrow - Thymus (Hassall's corpuscles)
Secondary: Spleen (blood)	Hilum - Trabeculae - Red pulp (Cords of Billroth, Marginal zone) - White pulp (Periarteriolar lymphoid sheaths)
Secondary: Lymph nodes (extracellular fluid)	Subcapsular sinus - Paracortex - Lymph vessels - High endothelial venules
Secondary: MALT (mucosa)	GALT - Peyer's patches

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Dansk (Danish)
n. - milt, tungsind, dårligt humør, spleen, livslede

Nederlands (Dutch)
milt, boosheid

Français (French)
n. - (Anat) rate, (fig) mauvaise humeur, spleen

Deutsch (German)
n. - Milz, Zorn

Ελληνική (Greek)
n. - (ανατ.) σπλήνα, (μτφ.) μελαγχολία, κακοκεφιά, οργή

Italiano (Italian)
milza

Português (Portuguese)
n. - baço (m), mau humor (fig.)

Русский (Russian)
селезенка, злоба, недоброжелательство, раздражительность

Español (Spanish)
n. - bazo

Svenska (Swedish)
n. - mjälte, dåligt humör, svårmod, mjältsjuka

中文（简体） (Chinese (Simplified))
脾脏, 怨恨, 坏脾气

中文（繁體） (Chinese (Traditional))
n. - 脾臟, 怨恨, 壞脾氣

한국어 (Korean)
n. - 비장, 악의 , 낙담

日本語 (Japanese)
n. - 脾臓, 腹立ち

العربيه (Arabic)
‏(الاسم) الطحال, حنق, غضب شديد‏

עברית (Hebrew)
n. - ‮טחול, דכדוך, כעס, זעם‬

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