MOD 3 - Cell Injury Flashcards
in cellular adaptation, increased cellular activity = ?
hyperplasia/hypertrophy
in cellular adaptation, decreased cellular activity = ?
atrophy
in cellular adaptation, change in cell morphology = ?
metaplasia
what are the 9 common aetiology of cell injury
physical trauma, oxygen availability, chemical agents, infectious organisms, irradiation, others - immunological, lack of essential nutrient/vitamin, genetic disorders, ageing
what are the 2 main causes of physical trauma?
mechanical trauma - disruption of cells & thrombosis leading to ischaemia, extremes of temperature - heat denatruration of proteins, ice crystals, fever
what are the 2 main causes of oxygen availability ?
hypoxia/anoxia - reduction or loss of oxygen delivered to cells often caused by ischaemia, reoxygenation - reprefusion - can generate oxygen free radical which can lead to further cell death ie reprefusion injury
what are some of the common chemical agents which can cause cell injury
alcohol, tobacco smoke, drugs, poisons, environmental, occupational
what are the common mechanism which infectious organisms cause cell injury
bacterila toxi - exotoxins & endotoxins, hijacking of cell machinery by viral infection - cell lysis, collateral damage by inflammation.
what happen to the level of Ca2+ should mitochondria is damaged as part of cell injury
ATP drop - Na pump deactivate - Ca2+ influx along with H2O, Na - cell swell
what happen to the level of pH should mitochondria should fail
ATP drop - glycolysis increase (anaerobic production of ATP - lactic acid) - pH drops - nuclear chromatin clumping
what happens to the level of protein synthesis should mitochondria should fail
ATP drops - ribosomes detachment - decreased protein synthesis - lipid deposition within the cell (steatosis) (usually exported accompanied by exportation of protein) ie fatty change / cloudy swelling
what is a free radical?
it is a highly reactive ions/molecules with single unpaired electron in outer orbital eg oxygen free radicals
what does free radical do to proteins and nucleic acids & cel membrane?
chain reaction with the cell membrane to produce more free radical, damages proteins and nucleic acid - causing apoptosis
how is free radical detoxified
by superoxide dismutase and antioxidants eg vitamins A, C&E
what does superoxide do in our body?
bacterial killing by neutrophils and macrophages depends on superoxide (another reaction used by the body to produce free radical for its own good)
what happens when cell membrane is defective?
loss of membrane barriers leads to break down in metabolite gradients - increased Ca2+ which activates a number of enzymes eg ATPase (ATP depletion), prtoeases (break down membrane& cytoskeletal proteins), endonuclease (responsible for DNA fragmentation)
what is necrosis?
cll death as a result of lethal cell injury - passive process