Cell Injury Flashcards
Distinguish reversible from irreversible cell injury.
Reversible: normal cell —injury—> altered cell —recovery—> normal cell
Permanent: normal cell —injury—> permanently altered cell
Identify the cytological changes that are associated with irreversible injury. (4)
Increased cytosolic Ca concentration
Mitochondria swelling, Ca precipitates form
Pyknotic nuclei
Apoptosis
Mallory’s hyaline in liver cells damaged by alcohol
Explain how steatosis occurs due to alcohol ingestion. (5 effects)
Alcohol gets metabolized to ACETATE, making NADH
- Mobilization of FA from body stores
- Decreased FA oxidation
- Increased TG synthesis
- Decreased lipoprotein synthesis
- Decreased transport/glycosylation/secretion of VLDL
Name and briefly distinguish 4 types of pathological necrosis.
- Coagulative necrosis: preservation of the structural outline of dead cells
- Liquefactive necrosis: tissue is digested and liquefied
- Caseous necrosis: mix of coagulative and liquefactive, seen in TB
- Enzymatic fat necrosis: necrosis of fat cells around damaged pancreas
Explain the relationship between hemochromatosis and cirrhosis.
Over time, hemochromatosis results in damage to cells due to a variety of mechanisms, including free radical injury
-> Cirrhosis
Name four features of cellular injury that are reversible.
Cell swelling: lost ability to regulate Na/K gradient
Loss of eosinophilia
Nuclear chromatin clumps
Lactic acidosis
Explain the role of calcium ions in irreversible cell injury.
Injurious agent -> increased cytosolic Ca ->…
- Activated phospholipases -> membrane damage
- Activated proteases -> disruption of membrane/cytoskeletal proteins
- Activated endonuclease -> damaged chromatin
- Activated ATPase -> decreased ATP
Key = MEMBRANE DAMAGE
Coagulative necrosis
Definition: preservation of the structural outline of dead cells
Mechanism: denaturation of enzymes and structural proteins; inactivation of enzymes prevents autolysis of the cell
- -Typically caused by ischemia, heavy metals, IR
- -Characterized by the ‘ghostly’ appearance of cells
Liquefactive necrosis
Definition: necrosis resulting in degradation and liquification of tissue
–Usually with extensive acute inflammation (infections)
Mechanism: release of lysosomal enzymes by necrotic cells or release of hydrolytic enzymes by neutrophils
Example: abscess, cerebral infarction (neutrophils come in and digest everything)
Caseous necrosis
A combination of coagulative and liquifactive necrosis
- -Classically associated with TB
- -Used to describe the amorphous, eosinophilic, acellular material in the center of a granuloma
Gangrenous necrosis
The consequence of bacterial colonization of tissue which has already undergone necrosis, usually due to ischemia
Enzymatic fat necrosis
Seen in pancreas
Lipases from pancreas, released in acute pancreatitis, digest surrounding fat, causing characteristic yellow flecks
Necrosis
Cell death at the level of tissues, often accompanied by an inflammatory infiltrate
Represents the morphologic changes from cell death in living tissues
Effect of enzymatic degradation (primarily by lysosomal enzymes) and denaturation of proteins
Causes of apoptosis (4)
Injury: radiation, toxins, free radicals
CTLs
Withdrawal of growth factors, hormones
Receptor ligand interactions (FAS, TNF)
Define steatosis. Is it reversible?
Accumulation of fat (triglyceride) in hepatocytes
“Fatty change”
Accumulation of lipid appears as clear circular areas in the cytoplasm of the liver cells
IT IS REVERSIBLE