<prompt> Endothelium activation refers to ?Aberration of anatomy of vessel wallIrreversible changes in functional state of vessel wallSmooth muscle proliferationIncreased expression of adhesion molecules for leukocyte recruitment  <response>: Ans. is d i.e., Increased expression of adhesion molecules for leukocyte recruitmentVascular endothelium in its normal, unactivated state does not bind circulating cells or impede their passage.In acute inflammation, the endothelium is activated and can bind leukocytes as a prelude to their exit from the blood vessels.Inflammatory mediators like thrombin, IL - 1, Platelet Activating Factor, Histamine And TNFactivate endothelial cells by increasing expression of adhesion molecules which can bind leukocytes for leukocyte recruitment. 