Autophagy (or autophagocytosis) (from the Ancient Greek αá½τÏŒφαγος autóphagos, meaning "self-devouring" and κÏτος kýtos, meaning "hollow" is the natural, regulated mechanism of the cell that removes unnecessary or disfunctional components. It allows the orderly degradation and recycling of cellular components.
Three forms of autophagy are commonly described: macroautophagy, microautophagy, and chaperone-mediated autophagy (CMA). In macroautophagy, cytoplasmic components (like mitochondria) are targeted and isolated from the rest of the cell within a double-membraned vesicle known as an autophagosome,[6][7] which, in time, fuses with an available lysosome, bringing its specialty process of waste management and disposal; and eventually the contents of the vesicle (now called an autolysosome) are degraded and recycled. In disease, autophagy has been seen as an adaptive response to stress, promoting survival of the cell; but in other cases it appears to promote cell death and morbidity. In the extreme case of starvation, the breakdown of cellular components promotes cellular survival by maintaining cellular energy levels.