L3 patho
•Cellular Response to Injury•
•Reversible cell injury•
1-*Definition of cell injury▪ Variety of changes (molecular and structural) of the stressed
cell due to external as well as internal environmental changes (altered hemostasis)
*Causes:
1) Hypoxia Caused by:
a) Ischemia:eg:arterial occlusion
b) Inadequate oxygenation.: heart or lung disease
c) Decreased oxygen carrying capacity of the RBCs: anemia
2) Infectious agents: Bacteria, viruses,
3) Physical agents: trauma, extremes of temperature, radiation
4) Chemical agents: concentrated acids, alkalies, poisons
5) Immunologic reactions: autoimmune diseases.
6) Nutritional disturbance: excess as in obesity or deficient as in protein and vitamins
deficiency.
7) Genetic and chromosomal defects
*Mechanisms of cell injury:
Biochemical disturbance of:
1) Cell membrane integrity which preserve cellular homeostasis.
2) Aerobic respiration involving oxidative phosphorylation by mitochondria and ATP Production
(energy source).
3) Synthesis of the enzymatic and structural protein.
4) The integrity of the cellular genetic apparatus (DNA-RNA).
5) Reactive oxygen metabolites
*Effects of cell injury:
The effects of cell injury depend up on
• the type and state of injured cell
• the duration, nature and severity of injurious agents.
This could be in the form of one of the following:
1- adaptation
2- reversible cell injury
3- irreversible cell injury
4- Intracellular and extracellular deposits.
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L3 patho
2-Reversible cell Injury
*Caused by mild injury or injury of short duration
* Active parenchymatous cells with higher rate of metabolism suffer more than supporting
stromal cells.(liver-kidney-heart)
*includes:
a) Acute cellular swelling (cloudy swelling and hydropic swelling).
b) Fatty change.
*A-cloudy swelling & hydropic degeneration
*Definition: Reversible cell injury characterized by mild (in cloudy) and excess (in hydropic)
intracellular water accumulation.
*Cause: mild injury or injury of short duration
*pathogenesis Injurious agents mainly hypoxia -----> inhibit oxidative
phosphorylation and ATP to formation by the mitochondria - ----> Loss of
ATP, which is the energy source causes:
1) Failure of the active cell membrane transport (sodium pump). Sodium
enters the cell (followed by water entry) and potassium diffuses out of
the cell.
2) Anaerobic ATP synthesis occurs and catabolites as lactate and inorganic
phosphates accumulate increasing the intracellular osmotic load resulting
in water entry.
*Pathological Features
-Gross picture The affected organ appears:
▪ swollen,
▪ soft
▪bloodless and pale due to compression of the capillaries by the swollen cells.
▪outer surface: smooth with rounded borders.
▪ cut surface: appears cloudy (less glistening), opaque and bulges outwards .
- Microscopic picture
CLOUDY SWELLING
▪1-The cells are swollen.
▪2- The cytoplasm is granular.
▪3-The nucleus is normal.
▪4- The capillaries between the cells are compressed.
HYDROPIC DEGENERATION
▪The cells are swollen.
▪ The cytoplasm is pale and Show multiple Vacuoles
▪The nucleus is normal.
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L3 patho
*Cell swelling due to accumulation of water
Hydropic change kidney. The tubular epithelial
cells are distended with cytoplasmic vacuoles while
the interstitial vasculature is compressed.
The nuclei of affected tubules are pale
Example
B- FATTY CHANGE/ degeneration
▪ Definition: Reversible cell injury
characterized by accumulation of natural fat
in parenchymatous cells.
▪ causes:
▪1) Hypoxia.
▪2) Viral infections e.g: HCV
▪3) Bacterial toxins of acute and chronic
infections.
▪ 4) Chemical agents as alcohol, phosphorous
and carbon tetrachloride.
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Cloudy swelling
L3 patho
Pathological Feature
Gross Picture
The affected organ is:
• enlarged and soft
• outer surface: smooth, pale yellow rounded
borders.
• The capsule is tense.
• The cut surface bulges and is greasy to touch.
•Fatty liver
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Microscopic Picture
•The cells appear swollen and
Show multiple tiny cytoplasmic vacuoles
(microvesicular steatosis)
•The fat globules fuse together forming a
big globule (macro vesicular steatosis) that
pushes and flattens the nucleus against
the cell membrane giving the cell a signet
ring appearance
•The swollen cells compress the
intercellular capillaries.
.•Steatosis= fatty degeneration
L3 patho
*Injury(Altered homeostasis)
Write the scientific term▪
Reversible morphological changes affecting cells in the absence of adaptation or in case of
exceeded cell adaptation
▪ I am a reversible cell change characterized by abnormal intracellular accumulation of fat
Q: ▪Can you explain the mechanism of abnormal intracellular accumulation of water?
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