Final answer:
The pathological death of cells within a living body can be due to necrosis or apoptosis. Necrosis is accidental cell death, whereas apoptosis is programmed cell death essential for maintaining cellular health and proper development.
Step-by-step explanation:
The pathological death of cells or tissues within the living body is called necrosis, which is an accidental death that occurs due to factors like injury or infection. In contrast, programmed cell death is a controlled process known as apoptosis. Apoptosis is essential for maintaining cellular health by eliminating damaged, superfluous, or potentially dangerous cells. For instance, during T-cell development, if a T-cell receptor binds to self proteins, the cell will undergo apoptosis to prevent autoimmune diseases. In the context of tissue development, apoptosis allows for the correct formation of structures by removing unneeded cells, such as the cells between developing digits. Moreover, disruptions in the cell cycle checkpoints can lead to apoptosis. If the checkpoints fail, cells may initiate apoptosis in response to biochemical anomalies, but if these fail, it may lead to unregulated cell division and cancer.
When discussing the death phase of cells in conditions like a culture medium accumulating toxic waste or end of lifecycle, we observe an exponential decrease in the number of living cells as they die off, which sometimes results in the release of nutrients for persisting cells. Overall, both necrosis and apoptosis are forms of cell death with profoundly different implications for the organism.