spleen (splēn) a large, glandlike organ situated in the upper left part of the abdominal cavity, lateral to the cardiac end of the stomach. Among its functions are the disintegration of erythrocytes and the setting free of hemoglobin, which the liver converts into bilirubin; the genesis of new erythrocytes during fetal life and in the newborn; serving as a blood reservoir; and production of lymphocytes and plasma cells.
Spleen
spleen
spleen [splēn]
spleen,
accessory spleen a connected or detached outlying portion, or exclave, of the spleen.
diffuse waxy spleen amyloid degeneration of the spleen involving especially the coats of the venous sinuses and the reticulum of the organ.
floating spleen , movable spleen one displaced and abnormally movable.
sago spleen one with amyloid infiltration, the malpighian corpuscles looking like grains of sand.
wandering spleen floating s.
waxy spleen a spleen affected with amyloid degeneration.
spleen (spl n)n. A large, highly vascular lymphoid organ, lying to the left of the stomach below the diaphragm and serving to store blood, disintegrate old blood cells, filter foreign substances from the blood, and to produce lymphocytes. |
Spleen
An organ located at the left side of the stomach that acts as a reservoir for blood cells and produces lymphocytes and other products involved in fighting infection.
spleen
Etymology: Gk, splen
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 because it contains localized lymphatic nodules. It is dark purple and varies in shape in different individuals and within the same individual at different times. The precise function of the spleen has baffled physiologists for more than 100 years, but research indicates it performs various tasks, such as defense, hemopoiesis, blood storage, and destruction and recycling of red blood cells and platelets. The spleen also produces leukocytes, monocytes, lymphocytes, and plasma cells in response to an infectious agent. It produces red cells before birth and is believed to produce red cells after birth only in extreme and hemolytic anemia. If the body suffers severe hemorrhage, the spleen can contract and increase the blood volume from 350 mL to 550 mL in less than 60 seconds. In the adult the spleen is usually about 12 cm long, 7 cm wide, and 3 cm thick. Its weight increases from 17 g or less in the first year to about 170 g at 20 years of age, then slowly decreases to about 122 g at 75 to 80 years of age. The variation in the weight of adult spleens is 100 to 250 g and, in extreme cases, 50 to 400 g. The size of the spleen increases during and after digestion and often increases during illness. Compare thymus. splenic [splen′ik] , adj.
spleen [splēn]
a large glandlike but ductless organ in the upper part of the abdominal cavity on the left side, lateral to the cardiac end of the stomach. Called also lien. adj., adj splen´ic. It is the largest collection of reticuloendothelial cells in the body and is composed of spongelike tissue of two types: red pulp, which is the dark reddish brown substance filling the interspaces of the sinuses of the spleen, and white pulp, which consists of sheaths of lymphatic tissue surrounding the arteries of the spleen. It is enclosed in a dense capsule. In a normal adult the spleen is about 12.5 cm long and weighs about 140 to 210 g. After gastric digestion and in the presence of disease the spleen enlarges.
During fetal life the spleen and liver produce erythrocytes, but after birth that function is taken over by the bone marrow. However, if there is bone marrow failure, the spleen may again produce erythrocytes. In the normal adult the spleen is a reservoir for blood, and contains a high concentration of erythrocytes. In times of exertion, emotional stress, pregnancy, severe bleeding, carbon monoxide poisoning, or other occasions when the oxygen content of the blood must be increased, the spleen contracts rhythmically to release its store of erythrocytes into the bloodstream.
The spleen also acts to help keep the blood free of unwanted substances, including wastes and infecting organisms. The blood is delivered to it by the splenic artery, and passes through smaller branch arteries into a network of channels lined with leukocytes known as phagocytes (see reticuloendothelial system). These clear the blood of old erythrocytes, damaged cells, parasites, and other toxic or foreign substances. Hemoglobin from the removed red cells is temporarily stored.
During fetal life the spleen and liver produce erythrocytes, but after birth that function is taken over by the bone marrow. However, if there is bone marrow failure, the spleen may again produce erythrocytes. In the normal adult the spleen is a reservoir for blood, and contains a high concentration of erythrocytes. In times of exertion, emotional stress, pregnancy, severe bleeding, carbon monoxide poisoning, or other occasions when the oxygen content of the blood must be increased, the spleen contracts rhythmically to release its store of erythrocytes into the bloodstream.
The spleen also acts to help keep the blood free of unwanted substances, including wastes and infecting organisms. The blood is delivered to it by the splenic artery, and passes through smaller branch arteries into a network of channels lined with leukocytes known as phagocytes (see reticuloendothelial system). These clear the blood of old erythrocytes, damaged cells, parasites, and other toxic or foreign substances. Hemoglobin from the removed red cells is temporarily stored.
accessory spleen a small mass of tissue elsewhere in the body, histologically and functionally identical with that composing the normal spleen.
spleen,
n 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.
spleen
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 spleen
a small mass of tissue, histologically and functionally identical with that composing the normal spleen but found elsewhere in the body.
slaughter spleen
see slaughter spleen.
Want to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit the webmaster's page for free fun content.
| ?Page tools | ||
|---|---|---|
|