I Cell Injury and Death

After you have completed this section of the chapter, you should be able to meet the following objectives:

♦ Describe the mechanisms whereby physical agents such
as blunt trauma, electrical forces, and extremes of
temperature produce cell injury

♦ Differentiate between the effects of ionizing and non-
ionizing radiation in terms of their ability to cause cell
injury

♦ Explain how the injurious effects of biologic agents differ
from those produced by physical and chemical agents

♦ State the mechanisms and manifestations of cell injury
associated with lead poisoning

♦ State how nutritional imbalances contribute to cell injury

♦ Describe three types of reversible cell changes that can
occur with cell injury

♦ Define free radical and relate free radical formation to cell
injury and death

♦ Describe cell changes that occur with ischemic and
hypoxic cell injury

♦ Relate the effects of impaired calcium homeostasis to cell
injury and death

♦ Differentiate cell death associated with necrosis and
apoptosis

♦ Cite the reasons for the changes that occur with the wet
and dry forms of gangrene

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UNIT II Cell Function and Growth

Cells can be injured in many ways. The extent to which any injurious agent can cause cell injury and death de­pends in large measure on the intensity and duration of the injury and the type of cell that is involved. Cell injury is usually reversible up to a certain point, after which irre­versible cell injury and death occur. Whether a specific stress causes irreversible or reversible cell injury depends on the severity of the insult and on variables such as blood supply, nutritional status, and regenerative capacity. Cell injury and death are ongoing processes, and in the healthy state, they are balanced by cell renewal.