Explain phagocytosis with a examples.
The word Phagocytosis breaks down into two sections; phago means eating and cyto means cell. Placed together the term phagocytosis simply means a cell that eats other cells. In the case of phagocytosis a white cell travels to an invading cell and eats it. During the process the cell changes shapes as it engulfs the microbe or other cell. The foreign body is ingested and becomes an intracellular vesicle.
The best examples of the phagocytes are found in the immune system where they perform the process in order to protect the body systems. Types of these cells included: Neutrophils, which address acute inflammation; Macrophages, which address chronic inflammation to reduce inflammation; and Dendritic Cells and B Lymphocytes.
Two difficult forms to destroy are Tuberculosis and Anthrax.
Phagocytosis is the capture, ingestion and destruction by a cell of particles or other cells. Phagocytosis ability is characteristic of certain cells, called phagocytes, like neutrophils and macrophages cells.
By phagocytosis pathogens are destroyed by the macrophages of immune system. Often these agents must be marked by antibodies to be recognized by phagocytes, leukocytes and lymphocytes.
1. Adherence -membrane of phagocytic cell adheres to the membrane of particle to be ingested; this phase is due to lectins on the surface of micro-organisms;
2. Ingestion -invagination of foreign particle ;
3. Digestion - performed by intercellular enzymes.
Phagocytosis is often accompanied by an abrupt rise in cellular oxygen consumption. Oxygenated compounds formed (H2O2, OH • radicals and O2) are in a very high concentration , where carries toxic effects for organisms ingested. Nitrogen monoxide formed leads tobacteria,parasites and fungi destroy.
Phagocytosis involves folding of the plasma membrane around the material that is being engulfed and the subsequent formation of an intracellular vesicle (phagosome). The phagosome fuses with a primary lysosome to form a secondary lysosome in which the food material is digested by enzymes.
Phagocytosis is found in many protozoa, where it serves for the nutrition of the cell. In the Metazoa it is a method of defence against foreign bodies like bacteria, dust and various colloids, e.g. in scavenging white blood cells. Residual undigested material is ejested by exocytosis.