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The spleen (, from Ancient Greek σπλήν, splḗn) is an organ found in almost all . Similar in structure to a large lymph node, it acts primarily as a blood filter.
The spleen plays important roles in regard to red blood cells (erythrocytes) and the immune system. It removes old red blood cells and holds a reserve of blood, which can be valuable in case of hemorrhagic shock, and also recycles iron. As a part of the mononuclear phagocyte system, it metabolizes hemoglobin removed from senescent red blood cells. The globin portion of hemoglobin is degraded to its constitutive , and the heme portion is metabolized to bilirubin, which is removed in the liver.
The spleen houses antibody-producing lymphocytes in its white pulp and monocytes which remove antibody-coated bacteria and antibody-coated blood cells by way of blood and lymph node circulation. These monocytes, upon moving to injured tissue (such as the heart after myocardial infarction), turn into and while promoting tissue healing. "Finally, the Spleen Gets Some Respect" By Natalie Angier, The New York Times, August 3, 2009 The spleen is a center of activity of the mononuclear phagocyte system and is analogous to a large lymph node, as its absence causes a predisposition to certain .
In humans, the spleen is purple in color and is in the left upper quadrant of the abdomen. (2025). 9780071466332, McGraw-Hill Medical. ISBN 9780071466332 The surgical process to remove the spleen is known as a splenectomy.
There are four ligaments attached to the spleen: gastrosplenic ligament, splenorenal ligament, colicosplenic ligament, and phrenocolic ligament.
| + 90% reference range (5th to 95th percentile) of spleen length by abdominal ultrasonography by height of the person |
| 8.9–11.3 cm |
| 8.5–12.5 cm |
| 8.6–13.1 cm |
| 8.6–13.4 cm |
| 9.3–13.4 cm |
| 9.3–13.6 cm |
| 9.7–14.3 cm |
| 10.2–14.4 cm |
The spleen, in healthy adult humans, is approximately in length. It weighs between and (standard reference range), correlating mainly to height, body weight and degree of acute congestion but not to sex or age.
Like the thymus, the spleen possesses only efferent lymphatic vessels. The spleen is part of the lymphatic system. Both the short gastric arteries and the splenic artery supply it with blood.
The are supplied by called penicilliary radicles.
The underlying central nervous processes coordinating the spleen's function seem to be embedded into the hypothalamic-pituitary-adrenal-axis, and the brainstem, especially the subfornical organ.
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| White pulp]]s. These are composed of: |
The spleen is the largest collection of lymphoid tissue in the body. It is normally palpable in preterm infants, in 30% of normal, full-term neonates, and in 5% to 10% of infants and toddlers. A spleen easily palpable below the costal margin in any child over the age of three to four years should be considered abnormal until proven otherwise.
Splenomegaly can result from antigenic stimulation (e.g., infection), obstruction of blood flow (e.g., portal vein obstruction), underlying functional abnormality (e.g., hemolytic anemia), or infiltration (e.g., leukemia or storage disease, such as Gaucher's disease). The most common cause of acute splenomegaly in children is viral infection, which is transient and usually moderate. Basic work-up for acute 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.
Calculators have been developed for measurements of spleen size based on CT scan, Ultrasound, and MRI findings.
A splenectomy (removal of the spleen) results in a greatly diminished frequency of memory B cells. A 28-year follow-up of 740 World War II veterans whose spleens were removed on the battlefield showed a significant increase in the usual death rate from pneumonia (6 rather than the expected 1.3) and an increase in the death rate from ischemic heart disease (41 rather than the expected 30), but not from other conditions.
Polysplenia is a congenital disease manifested by multiple small accessory spleens, rather than a single, full-sized, normal spleen. Polysplenia sometimes occurs alone, but it is often accompanied by other developmental abnormalities such as intestinal malrotation or biliary atresia, or cardiac abnormalities, such as dextrocardia. These accessory spleens are non-functional.
Splenic infarction occurs when the splenic artery or one of its branches are occluded, for example by a blood clot. Although it can occur , the typical symptom is severe abdominal pain in the left upper quadrant of the abdomen, sometimes radiating to the left shoulder. Fever and chills develop in some cases. It has to be differentiated from other causes of acute abdomen.
Etymologically, spleen comes from the Ancient Greek σπλήν ( splḗn), where it was the idiomatic equivalent of the heart in modern English. Persius, in his satires, associated spleen with immoderate laughter. The native Old English word for it is , now primarily used for animals; a loanword from Latin is .
In English, William Shakespeare frequently used the word spleen to signify melancholy, but also and merriment. In Julius Caesar, he uses the spleen to describe Cassius's irritable nature:
Must I observe you? must I stand and crouch Under your testy humour? By the gods You shall digest the venom of your spleen, Though it do split you; for, from this day forth, I'll use you for my mirth, yea, for my laughter, When you are waspish. Julius Caesar by William Shakespeare Act 4:1
The spleen, as a byword for melancholy, has also been considered an actual disease. In the early 18th century, the physician Richard Blackmore considered it to be one of the two most prevalent diseases in England (along with Tuberculosis). In 1701, Anne Finch (later, Countess of Winchilsea) had published a Ode, The Spleen, drawing on her first-hand experiences of an affliction which, at the time, also had a reputation of being a fashionably upper-class disease of the English. Both Blackmore and George Cheyne treated this malady as the male equivalent of "the vapours", while preferring the more Learned medicine terms "hypochondriasis" and "hysteria".Cheyne, George: The English Malady; or, A Treatise of Nervous Diseases of All Kinds, as Spleen, Vapours, Lowness of Spirits, Hypochondriacal and Hysterical Distempers with the Author's Own Case at Large, Dublin, 1733. Facsimile ed., ed. Eric T. Carlson, M.D., 1976, Scholars' Facsimiles & Reprints, Blackmore, Richard: Treatise of the spleen and vapors. London, 1725 In the late 18th century, the German language word Spleen came to denote eccentric and hypochondriac tendencies that were thought to be characteristic of English people.
In French language, "splénétique" refers to a state of pensive sadness or melancholy. This usage was popularised by the poems of Charles Baudelaire (1821–1867) and his collection Le Spleen de Paris, but it was also present in earlier 19th-century Romantic literature.
In , birds, and , white pulp is always relatively plentiful, and in birds and some mammals the spleen is typically rounded, but it adjusts its shape somewhat to the arrangement of the surrounding organs. In most vertebrates, the spleen continues to produce red blood cells throughout life; only in mammals this function is lost in middle-aged adults. Many mammals have tiny spleen-like structures known as haemal nodes throughout the body that are presumed to have the same function as the spleen. The spleens of aquatic mammals differ in some ways from those of fully land-dwelling mammals; in general they are bluish in colour. In and , they tend to be quite small, but in deep diving , they can be massive, due to their function of storing red blood cells.
Marsupials have y-shaped spleens, and it develops postnatally.
The only vertebrates lacking a spleen are the and (the early-branching Cyclostomata, or jawless fishes). Even in these animals, there is a diffuse layer of haematopoeitic tissue within the gut wall, which has a similar structure to red pulp and is presumed homologous with the spleen of higher vertebrates.
In mice, the spleen stores half the body's so that, upon injury, they can migrate to the injured tissue and transform into and to assist wound healing.
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Food
The spleen is one of the many organs that may be included in offal. It is not widely eaten as a principal ingredient, but cow spleen sandwiches are eaten in Sicily cuisine. Chicken spleen is one of the main ingredients of Jerusalem mixed grill.
Other animals
In cartilaginous and ray-finned fish, the spleen consists primarily of red pulp and is normally somewhat elongated, as it lies inside the lining of the intestine. In many , especially , it has the more rounded form and there is often a greater quantity of white pulp.
See also
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