Fagocitat

Fagocitat is a biological process by which cells engulf and internalize larger particles or other cells. The term comes from the Greek words "phagein" meaning "to eat" and "kytos" meaning "cell". This process is carried out by specialized cells called phagocytes, which are a type of white blood cell.

The mechanism of phagocitation involves the phagocyte extending its cell membrane, forming pseudopods, which surround and enclose the particle to be ingested. This creates a membrane-bound vesicle within the cell called a phagosome. Once inside the phagosome, the particle is typically subjected to degradation by enzymes released from lysosomes, which fuse with the phagosome.

Phagocitation plays a crucial role in the immune system, where phagocytes engulf and destroy pathogens such as bacteria and viruses, as well as cellular debris and foreign substances. This process is essential for clearing infections and maintaining tissue homeostasis. Beyond immunity, phagocitation is also involved in developmental processes, such as tissue remodeling during embryonic development, and in the removal of dead or dying cells in adult tissues.

Different types of phagocytes exist, including macrophages, neutrophils, and dendritic cells, each with specific roles and locations within the body. The efficiency and specificity of phagocitation can be enhanced by opsonization, a process where particles are coated with molecules like antibodies or complement proteins, making them more readily recognized and engulfed by phagocytes.