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Questions and Answers
Which type of necrosis is most commonly associated with ischemia and preserves the outlines of the cells?
Which type of necrosis is most commonly associated with ischemia and preserves the outlines of the cells?
What is a distinguishing feature of liquefactive necrosis?
What is a distinguishing feature of liquefactive necrosis?
Which type of necrosis is primarily associated with acute pancreatitis?
Which type of necrosis is primarily associated with acute pancreatitis?
Which type of necrosis results from cell-mediated immunity and is associated with tuberculosis?
Which type of necrosis results from cell-mediated immunity and is associated with tuberculosis?
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What is the primary fate of necrotic tissue?
What is the primary fate of necrotic tissue?
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Which types of necrosis generally occur in organs other than the brain?
Which types of necrosis generally occur in organs other than the brain?
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Which of the following statements about necrosis is true?
Which of the following statements about necrosis is true?
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Which of the following changes is characteristic of irreversible cell injury?
Which of the following changes is characteristic of irreversible cell injury?
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Study Notes
Cell Response to Injury
- Learning Objectives: Identify irreversible cell injury types; understand apoptosis and necrosis pathologically; and classify necrosis types.
Types of Cell Injury
- Reversible Cell Injury: Cellular swelling, fatty change
- Irreversible Cell Injury: Necrosis, apoptosis
Apoptosis
- Definition: Programmed cell death, affecting single or small groups of cells.
- Description: Cells "fall away" from surrounding tissue.
- Physiological Causes: Embryogenesis, cell loss in proliferating populations, hormone dependent death of host cells that have finished their function.
- Pathological Causes: DNA damage (anticancer drugs, radiation), cell death in certain infections.
Necrosis
- Definition: Death of large groups of cells or tissues within the living body. Can either follow or directly result from reversible injury.
- Causes: Trauma, radiation, physical agents, hypoxia, chemical agents, infections, immunological reactions.
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Types:
- Coagulative necrosis. Most common type, caused by ischemia (restricted blood supply). Preserves cell outlines. Affects all organs except the brain.
- Liquefactive necrosis. Occurs in the brain, caused by ischemia. Tissues become structureless due to necrotic cells and neutrophil enzyme action.
- Caseous necrosis. Induced by cell-mediated immunity, like tuberculosis. Affected tissue becomes yellowish, cheesy-like. Combination of coagulative and liquefactive necrosis.
- Fat necrosis. Enzymatic: occurs in acute pancreatitis, lipase enzymes digest peritoneal fat. Traumatic: occurs due to breast trauma, fat cells rupture and self-digest. Clinically, can be mistaken for cancer.
- Fate: Small area - engulfed by macrophages; drained by lymphatics. Large area - fibrosis, calcification.
Microscopic Picture of Necrosis
- Nuclear Changes: Live cells have normal nuclei; dead cells show pyknosis, karyorrhexis, karyolysis.
- Cytoplasmic Changes: Cell swelling; disruption of cell membranes; cytoplasmic eosinophilia; inflammation.
Microscopic Picture of Apoptosis
- Normal Cell: No inflammation.
- Cell Shrinkage: Cells shrink.
- Nuclear DNA Condensation: Nucleus condenses
- Membrane Blebbing (Projections): Membrane forms external blebs
- Apoptotic Body Formation: Cells break into apoptotic bodies.
- Nuclear Collapse: Nucleus collapses
- Continued Blebbing: Continued Membrane blebbing
Necrosis vs. Apoptosis
| Feature | Necrosis | Apoptosis |
|---|---|---|
| Definition | Death of large groups of cells. | Death of single or small groups of cells. |
| Physiological role | Pathologic | Physiologic, Pathologic |
| Cell size | Enlarged (swelling) | Reduced (shrinkage) |
| Nucleus | Changes: pyknosis → karyorrhexis → karyolysis | Fragmentation (round nucleosome) |
| Plasma membrane | Disrupted | Intact |
| Adjacent inflammation | Frequent | No |
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Description
Test your knowledge on cell injuries, focusing on irreversible types like necrosis and apoptosis. Understand the differences between reversible and irreversible cell injury as well as their pathological and physiological causes. This quiz will enhance your grasp of cellular responses to injury.
