Abnormalities of Growth, Differentiation & Morphogenesis (17) Flashcards
Cellular adaptation
Allows tissues and organs to cope with changes in demand (physiological/pathological)
What adaptations can occur? Change in..
Size, number, phenotype, metabolic activity, function due to changes in environment/demand (reversible)
Failure of adaption leads to
Sub-lethal/lethal cell injury (marked susceptibility to injury, stimulus is too severe)
Cells that don’t need to adapt
Fibroblasts - survive severe metabolic stress without harm e.g. absence of O2
Cells that adapt easily
Epithelial cells, labile cell population - active stem cell compartment
Cells that cannot adapt
Cerebral neurons - terminally differentiated, permanent cell population, high specialised function, easily damaged by environmental change
Physiological cellular adaption
Responding to normal changes in physiology or demand
Pathological cellular adaption
Responding to disease related changes
Increased cellular activity leads to
Increase size/number of cells
Types of adaptive response
Increased/decreased cellular activity, change of cell function and morphology
Hypertrophy
Increase in size of cells, increase in function capacity. increased metabolism, increased synthesis of structural components (seen in permanent cell populations - cardiac/skeletal muscle)
Hyperplasia
Increase in number of cells caused by cell division, possible in labile/stable cell populations
Subcellular hypertrophy and hyperplasia
Increase in size and number of subcellular organelles
Example of physiological hyperplasia
Hormonal, compensatory
Example of pathological hyperplasia
Excess hormones, growth factors