Reversible Cell Injury Flashcards
What are the 2 main types of reversible cell injury recognized by light microscopy?
1) Cellular swelling / hydropic degeneration
2) Fatty change
In general, when can different s types of cell changes develop after cell injury?
Cell swelling: within minutes
Cell death: irreversible injury may occur within 20 to 60 minutes
Ultrastructural (EM) and histochemical changes and release of enzymes occur within 2 hours.
Light microscopy changes may occur in 4-12 hours.
Gross changes are seen in 12-24 hrs.
Define cellular swelling
It is an early, sub-lethal manifestation of cell damage, characterized by increased cell size and volume.
What is the pathogenesis of cellular swelling?
Overload of intracellular water, evidenced by intracytoplasmic vacuolation, reflects alterations in electrolyte transport across plasma membrane and ER.
Failure of the cell to maintain homeostasis and regulate ingress and excretion of water results in diffuse disintegration of organelles, and cytoplasmic proteins.
What is the pathogenesis of cell swelling due to hypoxia?
Injury >> hypoxia >> decrease in ATP production >> Na and H2O move into cell; K moves out of cell >> Osmotic pressure increases >> More H2O moves into cell >> Cisternae of ER distend, rupture, and form vacuoles >> Extensive vacuolation >> Hydropic degeneration
What is the etiology (causative agents include any entity capable of disrupting cellular homeostasis) of cellular swelling.
Physical/mechanical injury Hypoxia Toxic agents Free radicals Viral organisms Bacterial organisms Immune-mediated injury
What could be the gross appearance of an organ affected by cellular swelling?
Slightly swollen, characterized by rounded edges
Paler than normal
Cut surface: affected tissue bulges and can not be put in correct apposition
Slightly heavy
What is the histological appearance of cells affected by cellular swelling?
A diluted cytoplasm
Affected cells may appear enlarged, with pale cytoplasm
Nucleus is often in normal position
If mild, cells may have a pale slightly granular appearance , also described as cloudy, “cloudy swelling”
Intermediate swelling, cells are swollen, vacuoles of,variable size appear in cytoplasm, “hydropic (vacuolar) degeneration”
Severe case, “ballooning degeneration”, whereby the cells enlarge and eventually rupture. Seen in certain viral diseases.
What are the ultrastructural changes of cellular swelling?
Plasma membrane: loss of microvilli, blebbing, myelin figures, loosening of intercellular attachments.
ER: dilation of cisternae, detachment and disintegration of polysomes
Mitochondria: swelling, appearance of small densities
Nucleus: clumping of chromatin, disintegration granular and fibrillar components
What is the prognosis of cellular swelling?
Early stage: if injurious agent is removed cell damage is reversible
It is irreversible if there’s abundant accumulation if intracellular water occurring in vacuolar degeneration and ballooning degeneration results in lysis of affected cell.
Which type of cells can fatty change occur?
Occurs in cells participating in fat metabolism (hepatocytes), and in cardiomyocytes, renal tubular epithelium,etc
Ex: hepatocytes, b/c decrease in protein synthesis»_space; decrease lipid transport out of hepatocytes
