What is "phagocytosis"

n. (context immunology cytology English) The process where a cell incorporates a particle by extending pseudopodia and drawing the particle into a vacuole of its cytoplasm.

n. process in which phagocytes engulf and digest microorganisms and cellular debris; an important defense against infection

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 vesicle known as a phagosome.

Phagocytosis is a specific form of endocytosis involving the vascular internalization of solids such as bacteria by an organism, and is therefore distinct from other forms of endocytosis such as the vesicular internalization of various liquids ( pinocytosis). 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 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.