Download Cellular response to stress

 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
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