CELL INJURY, INRACELLULAR ACUMULATIONS & NECROSIS
A normal cell is able to handle normal physiologic demands (homeostasis).
More extensive physiologic “stresses” or abnormal stimuli may produce a number of functional and structural alterations known as cellular adaptations e.g. hypertrophy and atrophy.
If limits of adaptive response are exceeded or when adaptation is not possible, a sequence of events follows, termed cell injury, which is reversible up to a certain point, but if the stimulus persists or is severe enough, the cell reaches a point of “no return” and suffers irreversible cell injury and cell death.
The principal patterns of cell death are necrosis and apoptosis.
Other morphologic cellular alterations in response to injury include:
■ Sub-cellular alterations involving cell organelles or the cytoskeleton.
■ Intracellular accumulations of a number of substances e.g proteins, lipids, carbohydrates, pigments, largely due to metabolic derangements in cells.
■ Pathologic calcification, a common consequence of cell and tissue injury.