Phagocitálást

Phagocitálást, commonly known as phagocytosis, is a fundamental cellular process where a cell engulfs large particles or other cells. This is a type of endocytosis, meaning it involves the cell membrane folding inward to form a vesicle around the ingested material. The term originates from Greek words "phagein" (to eat) and "kytos" (cell).

Phagocytosis is primarily carried out by specialized cells called phagocytes, which are key components of the immune system. These include macrophages, neutrophils, and dendritic cells. These cells patrol the body, identifying and engulfing foreign invaders such as bacteria, viruses, and fungi, as well as cellular debris, dead cells, and apoptotic bodies.

The process begins when a phagocyte recognizes a target particle. This recognition often involves specific receptors on the phagocyte's surface binding to molecules on the particle. Upon binding, the phagocyte extends its pseudopods (protrusions of the cell membrane) to surround the particle. The pseudopods fuse, enclosing the particle within a membrane-bound sac called a phagosome.

The phagosome then fuses with lysosomes, which are organelles containing powerful digestive enzymes and reactive oxygen species. This fusion forms a phagolysosome, where the engulfed material is broken down and neutralized. The resulting waste products are then expelled from the cell. Phagocytosis is crucial for host defense, tissue homeostasis, and developmental processes.