The complex process of leukocytes movement through the blood vessels are all except
Correct Answer: Phagocytosis
Description: Ref Robbins 8/e p44;9/e p71 Margination and Rolling. As blood flows from capillaries into postcapillary venules, circulating cells are swept by laminar flow against the vessel wall. Because the smaller red cells tend to move faster than the larger white cells, leukocytes are pushed out of the central axial column and thus have a better oppounity to interact with lining endothelial cells, especially as stasis sets in. This process of leukocyte accumulation at the periphery of vessels is called margination. If the endothelial cells are activated by cytokines and other mediators produced locally, they express adhesion molecules to which the leukocytes attach loosely. These cells bind and detach and thus begin to tumble on the endothelial surface, a process called rolling. Adhesion. The rolling leukocytes are able to sense changes in the endothelium that initiate the next step in the reaction of leukocytes, which is firm adhesion to endothelial sur- faces. This adhesion is mediated by integrins expressed on leukocyte cell surfaces interacting with their ligands on endothelial cells (Fig. 2-5 and Table 2-2). Integrins are transmembrane heterodimeric glycoproteins that mediate the adhesion of leukocytes to endothelium and of various cells to the extracellular matrix.
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