Cellular responses to stress and noxious stimuli:
Normal cells handle normal physiologic demands, maintaining a steady state called homeostasis.
More severe physiologic stresses and some pathologic stimuli may bring about a number of physiologic and
morphologic cellular adaptations, during which new but altered steady states are achieved, preserving the viability of the cell.
The adaptive response may consist of an increase in the number of cells, called hyperplasia, increase in the
sizes of individual cells, called hypertrophy.
Conversely, Atrophy is an adaptive response in which there is a decrease in the size and function of cells.
Nature of the stimulus and Cell response/adaptation towards it
- Increased demand = Hyperplasia and hypertrophy
- Decreased nutrients and stimuli = Atrophy
- Chronic irritation = Metaplasia
- Reduced oxygen supply, chemical and microbial injury = Acute reversible injury
- Progressive damage including the DNA = Necrosis and Apoptosis
- Metabolic alterations = Intercellular accumulations and calcification
