the inflammatory response is an important non-specific defense against tissue damage it begins when injured tissue cells release chemical signals that activate the endothelial cells of nearby capillaries within the capillaries adhesion molecules called selectins are displayed on the activated endothelial cells these adhesion molecules attract neutrophils slow them down and cause the neutrophils to Roll Along the endo iium as the neutrophils Roll Along the endothelium they encounter chemicals that activate integrin which are adhesion receptors on their surfaces these integrin then tightly attach to adhesion receptor molecules on the endothelial cells this causes the neutrophils to stick to the endothelium and stop rolling this accumulation of neutrophils along the walls of the capillary is referred to as margination the INF inammatory mediators released by the injured tissue bring about changes in the environment that cause masted cells to degranulate and release histamine histamine causes vasod dilation and an opening of the Junctions between the endothelial cells allowing fluid and Lucy to leave the capillary and enter the infected tissue the neutrophils now undergo dramatic changes in shape and squeeze through the endothelial wall into the inter itial tissue fluid this process is called extravasation the neutrophils followed by other types of phagocytes are attracted to the damage site by chemotactic substances released by bacteria and tissue breakdown products they ingest and Destroy invading bacteria