tailieunhanh - Ebook The washington manual of surgery: Part 2

(BQ) Part 2 book "The washington manual of surgery" presentation of content: Colon and rectum, anorectal disease, cerebrovascular disease, thoracoabdominal vascular disease, peripheral arterial disease, hemodialysis access, cardiac surgery, pediatric surgery, plastic and hand surgery,.and other contents. | > Table of Contents > 23 - Spleen 23 Spleen Timothy M. Nywening Maria B. Doyle A. Anatomy. The spleen is derived from the mesoderm and resides in the left upper quadrant of the abdomen, where it is protected by the ninth to eleventh ribs. The average adult spleen is 12 cm long × 7 cm wide × 4 cm thick and weighs between 1,000 and 1,500 g. The spleen is highly vascularized, receiving up to 5% of cardiac output. The splenic artery, a branch of the celiac axis, runs posterior to the pancreas and most commonly arborizes into multiple small arteries to enter the hilum of the spleen. The inferior mesenteric vein drains into the splenic vein, which ultimately joins with the superior mesenteric vein to form the portal vein. Accessory spleens are found in 10% to 20% of the population and can be located anywhere in the abdomen but are most commonly found in the splenic hilum (Fig. 23-1). B. Function. Histology of the spleen reveals highly vascularized red pulp interspersed with areas of white pulp. Red pulp consists of branching, thin walled sinuses and splenic cords filled with red blood cells (erythrocytes) and phagocytic cells. White pulp consists of T-cell rich periarteriolar sheaths, B-cell containing lymphoid nodules, and the marginal zone that serves as an interface between the lymphoid-dominant white pulp and erythrocyte-rich red pulp. These two histologies constitute the two major functions of the spleen: 1. Reticuloendothelial system: The red pulp serves to cull senescent erythrocytes and remodel healthy red cells. The spleen also serves as a reservoir for platelets. While extramedullary hematopoiesis uncommon in adults, the spleen may be a site of erythrocyte production in some disease states (., myelofibrosis). 2. Immune system: The spleen is involved in both the innate (opsonization) and adaptive (antigen presentation) immune system. Opsonization of pathogens by the complement system results in enhanced phagocytosis and clearance in the spleen. The white .