Apoptosis - definition and cell death

Apoptosis - definition and cell death

Apoptosis - the natural mechanism through which a cell engages in actions that lead to its death, often called programmed cell death or cell suicide. Apoptosis appears linked to SENESCENCE, an inherent limitation on the number of times a cell can divide. Both apoptosis and senescence play significant roles in the aging process. Once the cell initiates apoptosis there is no reversal; the process proceeds until the cell dies.

Apoptosis begins when the cell’s DNA fragments, signaling or switching the rest of the process in motion. Once activated apoptosis sets in motion the subsequent events result in the cell’s dismantling, assimilation, and recycling. In some respects cells become endlessly renewable resources for the body. Specialized cells called phagocytes break down dying and dead cells into basic components such as amino acids that other the body can use to construct new cells.

Apoptosis is necessary for growth, development, and change in the body. The process of the death of cells that experience injury or damage is called necrosis and by definition occurs outside the natural order of cell life expectancy. Extrinsic, rather than intrinsic, factors initiate necrosis.

See also CELL STRUCTURE AND FUNCTION; METABOLISM; PHAGOCYTE; PHAGOCYTOSIS; STEM CELL.

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Genetics and Molecular Medicine

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