Spleen Download For Pc [FULL]
Hanne Rylaarsdam
The spleen plays very important roles in regard to red blood cells (erythrocytes) and the immune system.[2] 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 amino acids, and the heme portion is metabolized to bilirubin, which is removed in the liver.[3][4]
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 dendritic cells and macrophages while promoting tissue healing.[5][6][7] 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 infections.[8][4]
The spleen is underneath the left part of the diaphragm, and has a smooth, convex surface that faces the diaphragm. It is underneath the ninth, tenth, and eleventh ribs. The other side of the spleen is divided by a ridge into two regions: an anterior gastric portion, and a posterior renal portion. The gastric surface is directed forward, upward, and toward the middle, is broad and concave, and is in contact with the posterior wall of the stomach. Below this it is in contact with the tail of the pancreas. The renal surface is directed medialward and downward. It is somewhat flattened, considerably narrower than the gastric surface, and is in relation with the upper part of the anterior surface of the left kidney and occasionally with the left adrenal gland.
An easy way to remember the anatomy of the spleen is the 135791011 rule. The spleen is 1 by 3 by 5 inches (3 by 8 by 13 cm), weighs approximately 7 oz (200 g), and lies between the 9th and 11th ribs on the left-hand side and along the axis of the 10th rib. The weight varies between 1 oz (28 g) and 8 oz (230 g) (standard reference range),[12] correlating mainly to height, body weight and degree of acute congestion but not to sex or age.[13]
Near the middle of the spleen is a long fissure, the hilum, which is the point of attachment for the gastrosplenic ligament and the point of insertion for the splenic artery and splenic vein. There are other openings present for lymphatic vessels and nerves. In addition to the splenic artery, collateral blood supply is provided by the adjacent short gastric arteries.[14]
Asplenia refers to a non-functioning spleen, which may be congenital, or caused by traumatic injury, surgical resection (splenectomy) or a disease such as sickle cell anaemia. Hyposplenia refers to a partially functioning spleen. These conditions may cause[6] a modest increase in circulating white blood cells and platelets, a diminished response to some vaccines, and an increased susceptibility to infection. In particular, there is an increased risk of sepsis from polysaccharide encapsulated bacteria. Encapsulated bacteria inhibit binding of complement or prevent complement assembled on the capsule from interacting with macrophage receptors. Phagocytosis needs natural antibodies, which are immunoglobulins that facilitate phagocytosis either directly or by complement deposition on the capsule. They are produced by IgM memory B cells (a subtype of B cells) in the marginal zone of the spleen.[23][24]
A splenectomy (removal of the spleen) results in a greatly diminished frequency of memory B cells.[25] 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.[26]
An accessory spleen is a small splenic nodule extra to the spleen usually formed in early embryogenesis. Accessory spleens are found in approximately 10 percent of the population[27] and are typically around 1 centimeter in diameter. Splenosis is a condition where displaced pieces of splenic tissue (often following trauma or splenectomy) autotransplant in the abdominal cavity as accessory spleens.[28]
Polysplenia is a congenital disease manifested by multiple small accessory spleens,[29] 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.
There has been a long and varied history of misconceptions regarding the physiological role of the spleen, and it has often been seen as a reservoir for juices closely linked to digestion.[35] In various cultures, the organ has been linked to melancholia, due to the influence of ancient Greek medicine and the associated doctrine of humourism, in which the spleen was believed to be a reservoir for an elusive fluid known as "black bile" (one of the four humours).[35] The spleen also plays an important role in traditional Chinese medicine, where it is considered to be a key organ that displays the Yin aspect of the Earth element (its Yang counterpart is the stomach). In contrast, the Talmud (tractate Berachoth 61b) refers to the spleen as the organ of laughter while possibly suggesting a link with the humoral view of the organ.
In English, William Shakespeare frequently used the word spleen to signify melancholy, but also caprice and merriment.[36] In Julius Caesar, he uses the spleen to describe Cassius's irritable nature:
The spleen, as a byword for melancholy, has also been considered an actual disease.[38] In the early 18th century, the physician Richard Blackmore considered it to be one of the two most prevalent diseases in England (along with consumption).[38] In 1701, Anne Finch (later, Countess of Winchilsea) had published a Pindaric 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.[39] Both Blackmore and George Cheyne treated this malady as the male equivalent of "the vapours", while preferring the more learned terms "hypochondriasis" and "hysteria".[38][40][41] In the late 18th century, the German word Spleen came to denote eccentric and hypochondriac tendencies that were thought to be characteristic of English people.[36]
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 Sicilian cuisine.[42] Chicken spleen is one of the main ingredients of Jerusalem mixed grill.[43]
In cartilaginous and ray-finned fish, the spleen consists primarily of red pulp and is normally somewhat elongated, as it lies inside the serosal lining of the intestine. In many amphibians, especially frogs, it has the more rounded form and there is often a greater quantity of white pulp.[44]
In reptiles, birds, and mammals, 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.[44] The spleens of aquatic mammals differ in some ways from those of fully land-dwelling mammals; in general they are bluish in colour. In cetaceans and manatees they tend to be quite small, but in deep diving pinnipeds, they can be massive, due to their function of storing red blood cells.
The only vertebrates lacking a spleen are the lampreys and hagfishes (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.[44]
An enlarged spleen usually doesn't cause symptoms. It's often discovered during a routine physical exam. A doctor usually can't feel the spleen in an adult unless it's enlarged. Imaging and blood tests can help identify the cause of an enlarged spleen.
The spleen is the largest secondary lymphoid organ in the body and, as such, hosts a wide range of immunologic functions alongside its roles in hematopoiesis and red blood cell clearance. The physical organization of the spleen allows it to filter blood of pathogens and abnormal cells and facilitate low-probability interactions between antigen-presenting cells (APCs) and cognate lymphocytes. APCs specific to the spleen regulate the T and B cell response to these antigenic targets in the blood. This review will focus on cell types, cell organization, and immunologic functions specific to the spleen and how these affect initiation of adaptive immunity to systemic blood-borne antigens. Potential differences in structure and function between mouse and human spleen will also be discussed.
A ruptured spleen is a medical emergency that occurs as a result of a break in your spleen's surface. Your spleen, situated just under your rib cage on your left side, helps your body fight infection and filter old blood cells from your bloodstream.
If the spleen is already enlarged due to infection or another cause, there is increased risk that the spleen might rupture. Contact sports that involve blows to the chest also increase the risk of a ruptured spleen.
If you've been diagnosed with an enlarged spleen, ask your health care provider whether you need to avoid activities for several weeks that could cause it to rupture. These might include contact sports, heavy lifting and other activities that increase the risk of stomach trauma.
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