Which abdominal structure is the largest of the lymphatic organs

The spleen is part of the lymphatic system , which is an extensive drainage network. The lymphatic lim-FAT-ik system works to keep body fluid levels in balance and to defend the body against infections.

It is made up of a network of lymphatic vessels that carry lymph — a clear, watery fluid that contains proteins, salts, and other substances — throughout the body. The spleen acts as a filter. It weeds out old and damaged cells and helps control the amount of blood and blood cells that circulate in the body. The spleen also helps get rid of germs.

It contains white blood cells called lymphocytes and macrophages. These cells work to attack and destroy germs and remove them from the blood that passes through the spleen. Bleeding may be minor or it may be a life-threatening medical emergency. The full blood count FBC test looks for abnormalities in the blood, such as unusually high or low numbers of blood cells.

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Skip to main content. Immune system. Home Immune system. Lymphatic system. Actions for this page Listen Print. Summary Read the full fact sheet. On this page. The lymphatic system and fluid balance Lymphatic vessels Spleen Thymus Other lymphoid tissue Lymph nodes Common problems involving the lymphatic system Where to get help.

The main roles of the lymphatic system include: managing the fluid levels in the body reacting to bacteria dealing with cancer cells dealing with cell products that otherwise would result in disease or disorders absorbing some of the fats in our diet from the intestine. The lymphatic system and fluid balance The blood in our blood vessels is under constant pressure. Lymphatic vessels The lymphatic vessels are found everywhere in our body.

Spleen The spleen is located in the abdominal tummy area on the left side, just under the diaphragm. It most commonly affects muscles that control the eyes and eyelids, resulting in droopy eyelids and difficulty making facial expressions; chewing, swallowing and speaking also become difficult.

In most cases of either MG or thymic cancer, thymectomy is recommended. Patients who have had a thymectomy may develop an immunodeficiency known as Good syndrome, which increases their susceptibility to bacterial, fungal and viral opportunistic pathogens; this condition is, however, relatively rare. When foreign antigens reach these organs, they initiate lymphocyte activation and subsequent clonal expansion and maturation of these important white blood cells.

Mature lymphocytes can then leave the secondary organs to enter the circulation, or travel to other areas, and target foreign antigens.

The spleen is the largest lymphoid organ. Due to its extensive vascularisation, the spleen is a dark-purplish oval-shaped organ; in adults it is approximately 12cm long, 7cm wide and weighs around g.

However, the size of the spleen can vary with circumstance: it diminishes in starvation, after heavy exercise and following severe haemorrhage Gujar et al, , and recent investigations indicate an increase in size in well-fed individuals and during the ingestion of food Garnitschnig et al, Blood enters the spleen from the splenic artery and leaves via the splenic vein, both of which are at the hilum; the splenic vein eventually becomes a tributary of the hepatic portal vein.

White pulp is a mass of germinal centres of dividing B-lymphocytes B-cells , surrounded by T-cells and accessory cells, including macrophages and dendritic cells; these cells are arranged as lymphatic nodules around branches of the splenic artery. As blood flows into the spleen via the splenic artery, it enters smaller, central arteries of the white pulp, eventually reaching the red pulp.

Splenic cords are made up of red and white blood cells and plasma cells antibody-producing B-cells ; therefore, the red pulp primarily functions as a filtration system for the blood, whereas the white pulp is where adaptive T- and B-cell responses are mounted.

The lymphatic nodules are arranged as sleeves around the blood vessels, bringing blood into the spleen. Within the white pulp are splenic nodules called Malpighian corpuscles, which are rich in B-cells, so this portion of lymphoid tissue is quick to respond to foreign antigenic stimulation by producing antibodies. The walls of the meshwork of sinuses in the red pulp also contain phagocytes that engulf foreign particles and cell debris, effectively filtering and removing them from circulation.

The haemoglobin is then split apart into haem and globin. The globin is broken down into its constituent amino acids, which can be utilised in the synthesis of a new protein. Haem consists of an iron atom surrounded four non-iron pyrrole rings.

The iron is removed and transported to be stored as ferritin, then reused to make new haemoglobin in the red bone marrow; macrophages convert the pyrrole rings into the green pigment biliverdin and then into the yellow pigment bilirubin. Both are transported to the liver bound to plasma albumin. Bilirubin, the more toxic pigment, is conjugated in the liver to form a less toxic compound, which is excreted in bile. In some animals — particularly athletic mammals such as horses, greyhounds and foxes — the spleen is also an important reservoir of blood, which is released into circulation during times of stress to improve aerobic performance.

In humans, however, the spleen contributes only a small percentage of blood cells into active circulation under physiological stress; the total stored blood volume is believed to be only ml Bakovic et al, The capsule of the spleen may contract following haemorrhage, releasing this reserve into circulation in the body. As the spleen is the largest collection of lymphoid tissue in the body, infections that cause white blood cell proliferation and antigenic stimulation may cause germinal centres in the organ to expand, resulting in its enlargement splenomegaly.

This happens in many diseases — for example, malaria, cirrhosis and leukaemia. The spleen is not usually palpable, but an enlarged spleen is palpable during deep inspiration.

Enlargement may also be caused by any obstruction in blood flow, for example in the hepatic portal vein. The anatomical position of the spleen coincides with the left tenth rib. Given its proximity to the abdominal wall, it is one of the most commonly injured organs in blunt abdominal trauma. The spleen is a fragile organ and, due to its highly vascularised nature, any injury causing rupture will rapidly lead to severe intraperitoneal haemorrhage; death may result due to massive blood loss and shock.

A moderate splenic injury may be managed conservatively, but an extensively burst or ruptured spleen may be treated by complete and prompt removal splenectomy. However, current data supports successful non-operative management of many traumatic splenic injuries, with the intention of reducing the need for complete removal Armstrong et al, The white pulp is lymphatic tissue consisting mainly of lymphocytes around arteries.

The red pulp consists of venous sinuses filled with blood and cords of lymphatic cells, such as lymphocytes and macrophages. Blood enters the spleen through the splenic artery , moves through the sinuses where it is filtered, then leaves through the splenic vein.