Chapter one Tissue and Cellular Injury Su Min

CPC case （ NO: A1-1 ） A 48 year old diabetic developed a non- healing ulcer on his right foot. The foot became black and developed a bad odor. Cultures were positive for anerobic organisms and gram-negative bacilli. Amputation was finally carried out when medical treatment was unsuccessful. What has happened to this patient's foot?

Major Objectives of this Chapter: To master the concepts of : 1. Adaptation of cells and tissues to injury. 2. Morphologic responses to cell injury including intracellular edema, fatty change, hyaline change, amyloidosis, mucoid degeneration, pathologic pigments. 3. Mechanisms, morphology and consequences of cell death (necrosis) and apoptosis.

The function and structure of normal cells is controlled by genetic programs for metabolism, differentiation, and specialization, by adjacent cells, and by the cellular environment. Most cells can adapt to normal physiologic changes (normal homeostasis). More stressful demands and some abnormal stimuli can initiate several functional and structural adaptations. In response to these abnormal stimuli, a new steady state is achieved, keeping the cell alive but changing its function or structure. Cells will be injured if they cannot adapt to the abnormal stimulus. Cell injury is reversible up to a certain point, but if the stimulus persists or is severe enough, the cell reaches the point of no return (cell death). This can be shown diagrammatically as follows:

（ From ROBBINS BASIC PATHOLOGY ， 2003 ）

Adaption Tissue and Cellular Degeneration: reversible injury Injury sublethal Necrosis: irreversible injury lethal