cell adaptation Flashcards
hypertrophy
increase in the size of cells. in cells that dont divide eg, cardiac and skeletal muscle. eg, exercise, hypertension
hyperplasia
increase in number of cells eg breast development at puberty/ psoriasis leading to thickened skin
atrophy
shrinkage in cell size due to loss of cell substance, functionally diminished but still alive/ ageing limb muscle
involution
reduction in number of functioning cells, due to reduction in functional demand. usually by programmed cell death (apoptosis)
metaplasia
change in cell type, reprogramming of stem cells. a survival mechanism in response to injury eg, smoking- specialised function is lost. can predispose to neoplasia
neoplasia- (new)(growth)
not an adaptive response. abnormal proliferation in the absence/removal of stimulus. doesn’t respond to normal signals controlling growth.
necrosis
severe damage to cell membranes, enzymes leak from lysosomes into the cytoplasm and digest the cell. cellular contents leak out of the cell eliciting a local reaction. pathologic
apoptosis
cells kill themselves as a result of lack of growth hormones/damage to DNA/proteins. Active, energy dependent, regulated, physiologic and pathologic. cells fragment into packages, plasma membrane remains intact- cells are removed without leakage of contents
failure of ATP production leading to necrosis
failure of energy dependent processes- damage to membrane- sodium flows into the cell, water follows- internal membranes swell and leak. Increased Ca++ initiates apoptosis due to cell damage. cell contents leak out causing inflammation
ischemia (leading to necrosis)
result of impaired vascular perfusion, depriving tissue of vital nutrients esp, oxygen.
infarction
death (necrosis) of tissue as a result of ischaemia
too little apoptosis examples
auto immune disease, cancer, chromic inflammatory diseases
too much apoptosis examples
immunodeficiency eg, AIDS, neurodegenerative diseases
