145 Questions
Which of the following is NOT a characteristic feature of reversible cell injury?
Fragmentation of the nucleus
Which of the following light microscopic nuclear changes reflects DNA damage?
All of the above
Which of the following is NOT a functional abnormality that characterizes irreversibly injured cells?
Increased cell division
Which type of necrosis is associated with the presence of caseous (cheese-like) material?
Caseous necrosis
Which of the following is NOT a distinct pathway for initiating apoptosis?
Necrotic pathway
The family of intracellular proteins that regulates the rate of apoptosis is known as the:
Bcl-2 family
Which mechanism promotes the phagocytosis of apoptotic cells by macrophages?
Both a and b
What is the primary characteristic of reversible cell injury caused by ischemia, as shown in the ultrastructural image?
Loss of microvilli and membrane blebs in the lumen
Which of the following is a characteristic of the nuclear changes seen in irreversible cell injury (necrosis)?
Fragmentation of the pyknotic nucleus
What is the main structural difference between normal and reversibly injured renal tubular epithelial cells, as shown in the light microscopy images?
Eosinophilic cytoplasm in normal cells, but swelling and blebs in reversibly injured cells
What is the correct sequence of nuclear changes that occur during irreversible cell injury (necrosis)?
Karyolysis, pyknosis, karyorrhexis
Which of the following is a characteristic of the ultrastructural changes seen in normal proximal tubular cells?
Abundant microvilli and mitochondria
What is the main difference in the cytoplasmic changes between reversible and irreversible cell injury, as described in the text?
Reversible injury causes cytoplasmic swelling and eosinophilia, while irreversible injury leads to ruptured cytoplasmic membranes
Which of the following best describes the ultrastructural changes seen in renal tubular cells undergoing reversible injury due to ischemia?
Loss of microvilli, membrane blebs in the lumen, and mildly dilated mitochondria
What is the main mechanism behind coagulative necrosis?
Denaturation of structural and enzymatic proteins
Which of the following is a characteristic feature of coagulative necrosis?
Preserved cellular outlines with loss of nuclei
What is the most common setting for tissues to undergo coagulative necrosis?
Tissues irreversibly injured by ischemia
Which term describes the fading of nuclear basophilia followed by the disappearance of the nucleus?
Karyolysis
What distinguishes coagulative necrosis from liquefactive necrosis?
Preservation of tissue architecture
Which term refers to the process where dead cells are proteolyzed after coagulative necrosis?
Autolysis
What happens to the phospholipid precipitates formed during cell necrosis?
They are phagocytosed by other cells or further degraded into fatty acids.
Which of the following is NOT a characteristic of necrotic cells observed under an electron microscope?
Continuous plasma and organelle membranes.
Which of the following nuclear changes is NOT observed during necrosis?
Chromatin condensation due to caspase activation.
What is the likely cause of the fading basophilia of chromatin observed during karyolysis?
Deoxyribonuclease (DNase) activity.
What is the appearance of the cytoplasm in necrotic cells?
Vacuolated and 'moth-eaten'.
What is the fate of the nucleus in a necrotic cell over time?
It completely disappears within 1-2 days.
What is the likely composition of the 'fluffy material' observed in necrotic cells under an electron microscope?
Denatured proteins.
What is the characteristic appearance of dry gangrene?
Pink-red areas corresponding to early ischemic necrosis, and blue-black areas indicating more advanced necrosis
What is the cause of wet gangrene?
Bacterial superinfection of long-standing ischemic necrosis, causing liquefactive changes
What is the mechanism behind the formation of chalky white deposits in fat necrosis?
Lipase from inflamed pancreas destroys membranes of adipocytes, converting triglycerides to fatty acids that combine with calcium
What is the characteristic finding in fat necrosis?
White foci of dead fat cells in the retroperitoneum
Which of the following is the mechanism behind fat necrosis?
Release of activated pancreatic lipases into the substance of the pancreas and the peritoneal cavity
What is the characteristic histologic finding in fat necrosis?
Necrotic adipocytes without peripheral nuclei, and phagocytosis of dead cells by macrophages and multinucleated giant cells
In which condition is fat necrosis commonly observed?
Acute pancreatitis
Where can fat necrosis occur?
In the adipose tissue of the pancreas, breast tissue, abdomen, and subcutaneous fat
Which type of necrosis is characterized by a 'cheesy' (yellow, friable) gross appearance?
Caseous necrosis
Which organism is most likely to be detected by performing an acid-fast stain on a lesion exhibiting caseous necrosis?
Mycobacterium tuberculosis
What is the main difference between dry gangrene and wet gangrene?
Dry gangrene has no superimposed infection, while wet gangrene has a superimposed infection.
What is the main structural difference between normal and reversibly injured renal tubular epithelial cells, as shown in the light microscopy images?
Normal cells have a more basophilic cytoplasm, while reversibly injured cells have a more eosinophilic cytoplasm.
What is the main mechanism behind the formation of chalky white deposits in fat necrosis?
Precipitation of calcium salts
What is the characteristic appearance of dry gangrene?
Dry, shrunken, and leathery
What is the primary mechanism behind the formation of calcium soaps during cell necrosis?
Calcification of fatty acid residues
Which of the following is NOT a characteristic of the ultrastructural changes seen in normal proximal tubular cells?
Dilated endoplasmic reticulum
Which of the following is the most accurate description of the nuclear changes observed during karyorrhexis?
Fragmentation of the pyknotic nucleus
What is the likely cause of the fading basophilia of chromatin observed during karyolysis?
Deoxyribonuclease (DNase) activity
Which ultrastructural feature is NOT characteristic of necrotic cells observed under an electron microscope?
Presence of intracytoplasmic lipid droplets
What is the likely composition of the 'fluffy material' observed in the cytoplasm of necrotic cells under an electron microscope?
Denatured proteins
What is the most common setting for tissues to undergo coagulative necrosis?
Ischemic injury
What is the characteristic histologic finding in fat necrosis?
Chalky white deposits
What is the likely fate of a necrotic nucleus that initially undergoes pyknosis?
It remains shrunken and fragmented.
What is a characteristic ultrastructural change observed in normal proximal tubular cells?
Mildly dilated mitochondria
Which of the following represents irreversible injury to renal tubular epithelium?
Ruptured cytoplasmic membranes and increased nuclear basophilia
What distinguishes reversible cell injury due to ischemia from normal proximal tubular cells?
Ruptured cytoplasmic membranes
Which characteristic is indicative of reversible injury due to decreased blood flow in the ultrastructural image?
Intact microvilli and mitochondriae
What type of injury is suggested by the presence of blebs, swelling, and eosinophilia in the cytoplasm?
Reversible injury due to ischemia
What is the probable outcome for a necrotic nucleus that exhibits karyorrhexis?
It regains its normal size and structure.
What is the characteristic appearance of wet gangrene?
Long-standing ischemic necrosis with bacterial superinfection, causing liquefactive changes
What is the mechanism behind the formation of chalky white deposits in fat necrosis?
Lipase from inflamed pancreas destroys membranes of adipocytes, converting triglycerides to fatty acids that combine with calcium
Where can fat necrosis occur?
In the adipose tissue of the pancreas, breast tissue, abdomen, and subcutaneous fat
What is the characteristic histologic finding in fat necrosis?
Phagocytosis of dead cells by macrophages and multinucleated giant cells
What is the likely cause of wet gangrene?
Bacterial superinfection of long-standing ischemic necrosis
What is the main mechanism behind coagulative necrosis?
Denaturation and coagulation of cellular proteins
Which of the following is NOT a characteristic of necrotic cells observed under an electron microscope?
Peripheral nuclei in adipocytes
Which term describes the process where dead cells are proteolyzed after coagulative necrosis?
Autolysis
What is the primary characteristic of reversible cell injury caused by ischemia, as shown in the ultrastructural image?
Swelling and disruption of cellular organelles
Which of the following statements accurately describes the ultrastructural changes seen in irreversible cell injury (necrosis)?
Ruptured plasma membrane, swollen mitochondria with dense deposits, and nuclear pyknosis
In the context of reversible cell injury, what is the significance of steatosis?
It indicates the accumulation of triglycerides within parenchymal cells, which is potentially reversible
Which of the following is the most likely cause of the rash and symptoms experienced by the 45-year-old woman after applying the moisturizing skin cream?
Type I hypersensitivity (IgE-mediated) reaction
What is the main characteristic that distinguishes necrosis from apoptosis?
Necrosis results in the leakage of cellular contents, while apoptosis does not
Which of the following best describes the mechanism behind coagulative necrosis?
Denaturation and coagulation of proteins due to ischemia or toxins
Which of the following statements accurately describes the nuclear changes observed during karyolysis?
The chromatin fades and the nucleus disappears
Which of the following best describes the underlying mechanism behind the formation of chalky white deposits in fat necrosis?
Precipitation of calcium salts from the breakdown of lipids
Phospholipid precipitates are phagocytosed by other cells.
False
Dead cells do not become calcified.
False
Mitochondria in necrotic cells exhibit a decrease in size with increased basophilia.
False
Nuclear pyknosis is characterized by DNA condensing into a solid shrunken mass.
True
Karyorrhexis involves the fusion of pyknotic nuclei.
False
The nucleus in a dead cell completely disappears within 1-2 days.
True
Karyolysis is primarily due to increased chromatin staining.
False
Apoptosis and necrosis are both forms of reversible cell injury.
False
Karyolysis is a light microscopic nuclear change that reflects DNA damage.
False
Liquefactive necrosis is characterized by a 'cheesy' gross appearance.
False
Apoptosis can be initiated through a single pathway.
False
Necrosis is a controlled process regulated by intracellular proteins.
False
Phagocytosis of apoptotic cells by macrophages does not involve any specific mechanisms.
False
Irreversibly injured cells always display the same two functional abnormalities.
False
Coagulative necrosis is characterized by the denaturation of structural and enzymatic proteins leading to cell lysis.
True
Necrosis can be defined as cell death that occurs due to mild damage to cell membranes and intact cellular contents.
False
Caseous necrosis is a morphologic pattern that is typically seen in tissues irreversibly injured by ischemia.
False
Gangrenous necrosis is a morphologic pattern characterized by eosinophilic, anucleate cells that may persist for days or weeks.
False
The mechanism behind fat necrosis involves the formation of chalky white deposits due to enzymatic destruction of cellular contents.
False
Liquefactive necrosis is a morphologic pattern associated with the formation of ghost outlines of dead cells.
False
Electron microscopy can reveal profound nuclear changes that end in nuclear dissolution during coagulative necrosis.
True
Caseous necrosis is typically seen in wet gangrene.
False
Gangrenous necrosis is commonly associated with ischemia.
True
Dry gangrene can transition to wet gangrene if an infection occurs.
True
Gas gangrene is caused by an acute necrotizing infection with Streptococcus pyogenes.
False
Caseating granuloma typically has a peripheral zone of eosinophils and mast cells.
False
Necrosis typically involves only the epidermis and dermis layers of the skin.
False
Acid-fast stain can be used to detect tuberculosis in lesions exhibiting caseous necrosis.
True
Fat necrosis primarily occurs in adipose tissue of the liver.
False
Wet gangrene results from long-standing ischemic necrosis without bacterial superinfection.
False
Dry gangrene is characterized by pink-red areas indicating advanced necrosis.
False
Calcium soaps are formed in fat necrosis due to the action of lipase on triglycerides.
True
Phagocytosis of dead cells in fat necrosis is primarily carried out by fibroblasts.
False
White foci of dead fat cells in retroperitoneum are a characteristic feature of dry gangrene.
False
'Wet gangrene' indicates dry, non-infectious necrosis.
False
Dead adipocytes in fat necrosis are phagocytosed by lymphocytes.
False
'Gangrenous Necrosis' refers to a pattern characterized by liquefactive changes.
True
'Fat Necrosis' primarily involves the release of activated pancreatic amylases into the peritoneal cavity.
False
What is the primary structural difference between normal and reversibly injured renal tubular epithelial cells, as shown in the light microscopy images?
Normal cells have abundant microvilli and mitochondria, while reversibly injured cells have loss of microvilli and mildly dilated mitochondria.
Which of the following is the most likely cause of the characteristic 'cheesy' (yellow, friable) gross appearance in a specific type of necrosis?
Formation of caseous (cheese-like) material due to coagulative necrosis.
What is the likely cause of the fading basophilia of chromatin observed during the nuclear change known as karyolysis?
Dissolution of the nucleus due to the action of DNase enzymes.
Which of the following is a characteristic of the ultrastructural changes seen in normal proximal tubular cells?
Abundant microvilli and mitochondria.
What is the primary mechanism behind the formation of chalky white deposits in fat necrosis?
Precipitation of calcium soaps and fatty acids due to the action of lipases.
Which of the following is a characteristic nuclear change observed during irreversible cell injury (necrosis)?
Nuclear fragmentation (karyorrhexis).
What is the likely outcome for a necrotic nucleus that exhibits the nuclear change known as karyorrhexis?
The nucleus will undergo dissolution due to the action of DNase enzymes (karyolysis).
What is the main characteristic that distinguishes liquefactive necrosis from other forms of necrosis?
The tissue is transformed into a gelatinous, partly solid and partly liquid mass
Which bacterial infections are commonly associated with liquefactive necrosis?
Staphylococcus aureus, Streptococcus pyogenes, and Clostridium perfringens
Where is liquefactive necrosis most commonly seen in the body?
In the central nervous system
What is the likely outcome of a cerebral infarction several years old?
The tissue is reduced to a cystic cavity with residual scar tissue
What is the primary cause of the liquefaction observed in cerebral infarctions?
Intense inflammatory response and release of leukocyte enzymes
What is the characteristic appearance of an acute ischemic infarction in the middle cerebral artery territory?
Early necrosis with tissue damage, 1-3 days after injury
What is the primary mechanism behind the formation of the cystic cavity in a cerebral infarction several years old?
Encapsulation and organization of the necrotic tissue by astrocytes
What is the primary mechanism responsible for the digestion of cellular contents during necrosis?
Autolysis, involving enzymes from the lysosomes of the dying cells themselves
Which of the following cytoplasmic changes is characteristic of necrotic cells observed under a light microscope?
Formation of myelin figures, which are whorled phospholipid masses derived from damaged cell membranes
What is the primary reason for the increased eosinophilia (pink staining) observed in the cytoplasm of necrotic cells?
Increased binding of eosin dye to denatured cytoplasmic proteins
What is the primary reason for the glassy, homogeneous appearance of the cytoplasm in necrotic cells?
Loss of glycogen particles due to enzymatic digestion
Which of the following statements about the time course of necrosis is correct?
Digestion of cellular contents and the host response take hours to develop
Which of the following statements accurately describes the formation of myelin figures in necrotic cells?
Myelin figures are derived from damaged cell membranes and their phospholipid content
What is the primary mechanism responsible for the recruitment of leukocytes during necrosis?
The local host reaction, called inflammation, that attempts to eliminate dead cells
What is the primary mechanism behind fat necrosis?
Release of activated pancreatic lipases into the peritoneal cavity
What is the characteristic appearance of dry gangrene?
Pink-red areas indicating early ischemic necrosis and blue-black areas indicating advanced necrosis
What is the primary cause of wet gangrene?
Bacterial superinfection of long-standing ischemic necrosis
Which of the following is the most accurate description of the nuclear changes observed during karyolysis?
Fading of nuclear basophilia followed by the disappearance of the nucleus
What is the characteristic histologic finding in fat necrosis?
White foci of dead fat cells in the retroperitoneum
Which of the following statements accurately describes the relationship between gangrenous necrosis and ischemia?
Gangrenous necrosis is commonly associated with ischemia
What is the likely fate of a necrotic nucleus that initially undergoes pyknosis?
It will eventually disappear through the process of karyolysis
What is the primary characteristic of fat necrosis?
Formation of chalky-white calcium deposits due to fat saponification
Which of the following conditions is associated with fibrinoid necrosis?
Polyarteritis nodosa
What is the characteristic microscopic finding in fibrinoid necrosis?
Bright pink and amorphous appearance in H&E stains
Which of the following is NOT a characteristic feature of reversible cell injury?
Irreversible DNA damage and karyolysis
What is the primary mechanism behind coagulative necrosis?
Coagulation of intracellular proteins due to ischemia
Which of the following is a characteristic feature of caseous necrosis?
Development of cheese-like necrotic material
What is the primary distinguishing feature of necrosis compared to apoptosis?
Necrosis results in the release of cellular contents and inflammation
Study Notes
- Reversible cell injury due to ischemia in renal tubular epithelium shows cytoplasmic blebs, swelling, and eosinophilia.
- Irreversible cell injury (necrosis) in renal tubular epithelium is characterized by ruptured cytoplasmic membranes and nuclear changes (karyolysis, pyknosis, karyorrhexis).
- Coagulative necrosis is the most common setting in tissues irreversibly injured by ischemia, leading to denaturation of structural and enzymatic proteins, cell lysis, and eosinophilic, anucleate cells persisting for days.
- Gangrenous necrosis is a distinctive form of necrosis usually affecting body parts like the leg, involving epidermis, dermis, subcutis, and deeper tissues, leading to dry or wet gangrene depending on the presence of infection.
- Fat necrosis is characterized by focal areas of fat destruction and can occur in various tissues like the pancreas, breast, abdomen, and subcutaneous fat, often due to the release of activated pancreatic lipases.
- Caseous necrosis is a form of coagulation necrosis associated with granulomatous inflammation, seen in tuberculosis and certain fungal infections, presenting with a "cheesy" gross appearance and distinctive histopathologic features like granulomas.
- Nuclear changes in necrotic cells can present in three patterns: karyolysis (fading of nuclear basophilia), pyknosis (nuclear shrinkage and increased basophilia), and karyorrhexis (fragmentation of pyknotic nucleus).
- Electron microscopy of necrotic cells reveals discontinuities in plasma and organelle membranes, dilation of mitochondria, disruption of lysosomes, and intracytoplasmic myelin figures.
Test your knowledge on apoptosis and necrosis in cell injury and cell death. Learn about the microscopic morphologic features of reversible and irreversible cell injury, as well as nuclear changes reflecting DNA damage.
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