Phagocytization

Phagocytization is a cellular process by which certain cells engulf and internalize large particles, such as microorganisms, foreign substances, or dead cells. The term "phagocytosis" originates from the Greek words "phagein" meaning "to eat" and "kytos" meaning "cell." This essential mechanism plays a crucial role in the immune system and in the removal of cellular debris.

The process begins when a phagocyte, a type of white blood cell, recognizes a target particle. This recognition is often mediated by specific receptors on the phagocyte's surface that bind to molecules on the particle. Following recognition, the phagocyte extends its cell membrane, forming pseudopods that surround and engulf the particle. This creates a vesicle within the cell called a phagosome.

Once internalized, the phagosome fuses with lysosomes, which are organelles containing digestive enzymes and toxic molecules. This fusion creates a phagolysosome, where the ingested material is broken down and neutralized. The resulting waste products are then expelled from the cell through exocytosis. Key phagocytic cells in mammals include macrophages, neutrophils, and dendritic cells. This process is vital for defending the body against pathogens and maintaining tissue homeostasis.