Fagocitálást

Fagocitálást is the process by which certain cells, known as phagocytes, engulf and absorb foreign particles, pathogens, or dead cells. This is a crucial part of the innate immune system, acting as a first line of defense against invading microorganisms. The term itself derives from Greek words meaning "to eat" and "cell."

The process of phagocitálást typically involves several distinct steps. First, the phagocyte recognizes the target particle, often through specific receptors on its surface that bind to molecules present on the pathogen or cell debris. Once recognized, the phagocyte extends its cell membrane to surround the particle, forming a pocket. This pocket then pinches off from the cell membrane, creating a vesicle within the phagocyte called a phagosome.

Inside the phagosome, the engulfed material is subjected to degradation. The phagosome fuses with lysosomes, which are organelles containing powerful digestive enzymes and reactive oxygen species. This fusion creates a phagolysosome, where the foreign material is broken down into smaller, harmless components. These components can then be released from the cell or used by the phagocyte.

Key phagocytic cells in the human body include macrophages and neutrophils. Macrophages are found in tissues throughout the body, while neutrophils are abundant in the bloodstream and are often among the first responders to sites of infection or injury. Fagocitálást plays a vital role in clearing infections, removing cellular waste, and initiating adaptive immune responses by presenting fragments of the engulfed material to other immune cells.