Cells respond to changes in their environment, constantly adjusting their structure and function to accommodate changing demands and extracellular stresses in order to maintain a steady state, a process called homeostasis .
As cells encounter physiologic stresses or injurious stimuli, they can undergo adaptation , achieving a new steady state and preserving viability and function.
If the adaptive capability is exceeded or if the external stress is inherently harmful, cell injury occurs.
Cell injury is the basis of all disease.
Within certain limits, injury is reversible , and homeostasis is restored; however, if the stress is severe or persistent, it results in irreversible injury and death of the affected cells. Cell death is a crucial event in the development of many diseases.