Phagocytosis is a cellular process in which a cell engulfs and internalizes large particles such as bacteria, dead cells, or foreign substances by wrapping its plasma membrane around the particle to form an internal vesicle called a phagosome. This process is mainly used by immune cells like macrophages and neutrophils to remove pathogens and cell debris as part of the body's defense mechanism.
Phagocytosis Process
- The process begins when a phagocytic cell detects and binds to a particle via specific receptors on its surface.
- The cell's cytoskeleton rearranges to extend membrane protrusions (pseudopods) around the particle, eventually enclosing it within a membrane-bound vesicle called a phagosome.
- The phagosome fuses with a lysosome, forming a phagolysosome where enzymes and reactive oxygen species digest the engulfed material.
Biological Significance
- Phagocytosis is crucial in immune defense, clearing pathogens such as bacteria.
- It also removes dead or damaged cells to maintain tissue health.
- Impaired phagocytosis can lead to infections or autoimmune diseases.
Key Cells Involved
- Macrophages: Tissue-resident cells that perform phagocytosis and antigen presentation.
- Neutrophils: Circulating white blood cells that rapidly engulf pathogens during infection.
In summary, phagocytosis is a vital mechanism of the immune system for eliminating harmful particles and maintaining tissue homeostasis.
