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Cellular response to stress Maybe sudden or gradual and it differs according to the age . Sudden as in case of blood loss . Gradual as in case of diseases . Cellular response to stress Non Adaptive Adaptive 2Inflammation and repair 3 – Immune response 1- change in structure , number , size and type of cells . e.g.: Atrophy Hypertrophy Hyperplasia Metaplasia Degeneration Necrosis Dysplasia Neoplasia Adaptive changes 1- Atrophy : decrease in cell size Causes : either physiological or pathological 1- Disuse atrophy is seen in muscles of paralysed limlos . 2- Denewation and ischaemia : localized atrophy as which appear in extremety affected by peripheral vas-cular disease . 3- nutrition as in starvation . 2- Hypertrophy : Increase in cell size due to in functional demand . Causes : either physiological or pathological Physiological : 1- hypertrophy of skeletal muscles in Exercise . 2 – hypertrophy of uterine muscles in pregnancy . Pathological: Adaptive : Myocardium hypertrophy in hypertension Compensatory : Enlargement of the remaining part of the kidney occurs after nephrectomy 3- Hyperplasia : Increase in number of cells capable of mitotic division Such as : epidermis , glandular tissues , epithelium of intestine . e.g. : Breast and Uterus enlargement during pregnancy . 4- Metaplasia : Conversion of one adult cell type to another within the same tissue . Non adaptive changes Dysplasia : Variation in size and shape caused by chronic irritation or inflammation . It might lead to Neoplasia . Effects of cell injury : maybe 1- Reversible (degeneration ) : mild injury or injury of short duration . It includes Cloudy swelling Hydropic swelling Fatty changes 2- Irreversible : sever injury or injury of long duration . There are 3 types : necrosis apoptosis gangrene Degeneration Reversible sublethal tissue injury it includes the following mechanisms : 1- Cloudy swelling : Accumulation of water caused by ATP . 2- Hydropic swelling : Excess water accumulation inside the cells . 3- Fatty changes : Pathological accumulation of excess fat in the cells . Miscellaneous tissue accumulation and deposit: 1-extracellular acccumulation of amyloid (abnormal protein)in case of amyloidosis 2-intracellular and extracellular accumulation of carbon incase of anthracosis Necrosis Irreversible lethal cell injury Necrosis mean death of the cell /organ or tissue in necrosis the microscopic changes are apparen in the nucleus and the cytoplasmic contents. In necrosis there is realease of enzymes which ; 1-causes structural changes (autolysis) 2-released in the blood and help in the diagnosise Types of necrosis : 1-coagulative necrosis e.g.in case of infarction (infarction occurs when the artery that supplies an organ becomes occluded 2-liquefactive necrosis ;e.g. abscess 3- caseous necrosis e.g.tuberculosis 4- fat necrosis it is of two types ; 1-traumatic fat necrosis occurs in breast 2-enzymatic fat necrosis occurs in pancreas Apoptosis Programmed cell death affecting a singel cell or small group of cell . it is either physiological or Pathological Normal cell turn over physiologicai12-embryonic development 3-endometrium during the menstwal cycle Pathological; as radiation cell injury and liver injury in viral hepatitis Gangrene Means ;necrosis+putrefaction Types: 1- dry gangrene: gradual arterial occlusion usually affect the extremeties.the skin is dark brown or black and dry . there line of demarcation between the gangrenous area and the healthy tissues best e.g is senile gangrene of the lower limb 2- Moist gangrene: sudden arterial and venous occlusion usually affect the intenal organs or extremeties bacterial invasion plays an important role . the skin is black moist and foulodour (d.t.bacteria)the symptoms are severe And may lead to death . no line of demarcation. Best e.g. strangulated hernia 3-gas gangrene: due to infection with gas producing organism e.g.clostridium welchii good luck