is the process by which phagocytic cells enter the tissues from capillaries
Chemotaxis
title: Phagocytosis text: Phagocytosis In cell biology, phagocytosis () is the process by which a cell - often a phagocyte or a protist - engulfs a solid particle to form an internal compartment known as a phagosome. It is distinct from other forms of endocytosis, like pinocytosis, that involve the internalization of extracellular liquids. Phagocytosis is involved in the acquisition of nutrients for some cells. The process is homologous to eating at the level of single-celled organisms; in multicellular animals, the process has been adapted to eliminate debris and pathogens, as opposed to taking in fuel for cellular processes, except in the case title: Phagocytosis text: phagocytes (such as dendritic cells) to engage in phagocytosis. Some white blood cells in human immune system perform phagocytosis by gulping in some pathogenic and disease causing cells. Leukocytes generate hydrogen cyanide during phagocytosis, and can kill bacteria, fungi, and other pathogens by generating several other toxic chemicals. Following apoptosis, the dying cells need to be taken up into the surrounding tissues by macrophages in a process called efferocytosis. One of the features of an apoptotic cell is the presentation of a variety of intracellular molecules on the cell surface, such as calreticulin, phosphatidylserine (from the inner layer of the title: Phagocyte text: located in the tissue near the infection site. Another group of chemical attractants are cytokines that recruit neutrophils and monocytes from the blood. To reach the site of infection, phagocytes leave the bloodstream and enter the affected tissues. Signals from the infection cause the endothelial cells that line the blood vessels to make a protein called selectin, which neutrophils stick to on passing by. Other signals called vasodilators loosen the junctions connecting endothelial cells, allowing the phagocytes to pass through the wall. Chemotaxis is the process by which phagocytes follow the cytokine "scent" to the infected spot. Neutrophils travel across title: Phagocytosis text: of the animal "Trichoplax". In an organism's immune system, phagocytosis is a major mechanism used to remove pathogens and cell debris. For example, when a macrophage ingests a pathogenic microorganism, the pathogen becomes trapped in a phagosome which then fuses with a lysosome to form a phagolysosome. Within the phagolysosome, enzymes and toxic peroxides digest the pathogen. Bacteria, dead tissue cells, and small mineral particles are all examples of objects that may be phagocytized. Phagocytosis was first noted by Canadian physician William Osler (1876), and later studied and named by Élie Metchnikoff (1880, 1883). Phagocytosis in mammalian immune cells is title: Phagocyte text: normal healthy function of cells. The body has to rid itself of millions of dead or dying cells every day, and phagocytes play a crucial role in this process. Dying cells that undergo the final stages of apoptosis display molecules, such as phosphatidylserine, on their cell surface to attract phagocytes. Phosphatidylserine is normally found on the cytosolic surface of the plasma membrane, but is redistributed during apoptosis to the extracellular surface by a hypothetical protein known as scramblase. These molecules mark the cell for phagocytosis by cells that possess the appropriate receptors, such as macrophages. The removal of dying cells