Cellular Responses and Adaptations to Stress Lecture Notes PDF

Cellular Responses and Adaptations to Stress  Cellular Response to Stress Normal cell needs special conditions “environment” to function properly. Cells try to adapt to surrounding stimuli or changes → so it can survive.  Cellular Responses  Adaptation: hypertrophy,...

Cellular Responses and Adaptations to Stress  Cellular Response to Stress Normal cell needs special conditions “environment” to function properly. Cells try to adapt to surrounding stimuli or changes → so it can survive.  Cellular Responses  Adaptation: hypertrophy, hyperplasia, atrophy, metaplasia.  Injury: reversible and irreversible (cell death).  Intracellular accumulation, calcification  Cellular aging.  Cellular Adaptations Reversible changes in size, number, phenotype, metabolic activity or function in response to changes in their environment.  Hypertrophy Hypertrophy is an increase in cell size resulting in increase in the size of the organ.  Hypertrophy Muscle  Hyperplasia: Increased number of cells resulting in increased mass of the organ or tissue.  Atrophy  Reduced size of tissue or organ due to loss of cell substance (size and number).  Atrophy Atrophy of muscle fibers.  Atrophy Brain  Metaplasia  Metaplasia is a “reversible” change in which one differentiated cell type (epithelial or mesenchymal) is replaced by another cell type.  New epithelium is better in dealing with the current stress or irritation.  Metaplasia Replacement of ciliated columnar epithelium by stratified squamous epithelium in the respiratory tract of a smoker.