Pathology the big Picture

Pathology, in the broadest terms, is the study of disease. Disease occurs for many reasons. Some diseases represent spontaneous alterations in the ability of a cell to proliferate and function normally, and in other cases, disease results when external stimuli produce changes in the cell's environment that make it impossible for the cell to maintain homeostasis. In such situations, cells must adapt to the new environment. These adaptations include hyperplasia, hypertrophy, atrophy, and metaplasia, and can be physiologic or pathologic, depending upon whether the stimulus is normal or abnormal. A cell can adapt to a certain point, but if the stimulus continues beyond that point, failure of the cell, and hence the organ, can result. If cells cannot adapt to the pathologic stimulus, they can die. This chapter will discuss cellular adaptation, cell injury, cellular accumulations, and cellular aging.