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Questions and Answers
What characterizes caseous necrosis?
What characterizes caseous necrosis?
Which condition is an example of fat necrosis?
Which condition is an example of fat necrosis?
What causes fibrinoid necrosis in small blood vessels?
What causes fibrinoid necrosis in small blood vessels?
Which feature is characteristic of apoptotic cells?
Which feature is characteristic of apoptotic cells?
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Which of the following is NOT a physiologic example of apoptosis?
Which of the following is NOT a physiologic example of apoptosis?
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What is a common physiologic role for apoptosis?
What is a common physiologic role for apoptosis?
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What is one of the early steps in the morphological appearance of apoptosis?
What is one of the early steps in the morphological appearance of apoptosis?
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In pathological apoptosis, which of the following represents an apoptotic hepatocyte?
In pathological apoptosis, which of the following represents an apoptotic hepatocyte?
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Which factor can lead to fibrinoid necrosis?
Which factor can lead to fibrinoid necrosis?
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Apoptosis typically results in which of the following?
Apoptosis typically results in which of the following?
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What is characterized by the complete loss of cell and tissue structure due to liquefaction?
What is characterized by the complete loss of cell and tissue structure due to liquefaction?
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Which type of necrosis is associated with myocardial infarction?
Which type of necrosis is associated with myocardial infarction?
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What is the initial change seen in necrotic cells followed by a series of morphological alterations?
What is the initial change seen in necrotic cells followed by a series of morphological alterations?
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Which term describes the characteristic appearance of a necrotic area in gross examination?
Which term describes the characteristic appearance of a necrotic area in gross examination?
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What type of necrosis is specifically defined as a combination of coagulative and liquefactive necrosis?
What type of necrosis is specifically defined as a combination of coagulative and liquefactive necrosis?
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Which process involves the preservation of cell outlines while losing cellular details?
Which process involves the preservation of cell outlines while losing cellular details?
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Which of the following correctly describes the term 'pyknosis'?
Which of the following correctly describes the term 'pyknosis'?
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Which of the following types of necrosis is primarily associated with enzymatic digestion by neutrophils and macrophages?
Which of the following types of necrosis is primarily associated with enzymatic digestion by neutrophils and macrophages?
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Which type of necrosis is typically noted for its pale yellow color and defined margins?
Which type of necrosis is typically noted for its pale yellow color and defined margins?
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Which of these changes does NOT occur in necrotic cells?
Which of these changes does NOT occur in necrotic cells?
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Study Notes
Cell Injury - 3
- Intended Learning Objectives: Recall cell death types, describe necrotic cell types, examples, and features, describe apoptotic cell morphology, and compare necrosis and apoptosis.
Types of Cell Death
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Necrosis: Local death of a group of cells within a living body. It's characterized by the breakdown (rupture) of cell membrane and enzymatic digestion of cellular contents.
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Apoptosis: Genetically controlled, programmed single cell death. Apoptosis is characterized by cell shrinkage, fragmentation of the nucleus, and formation of apoptotic bodies, which are later phagocytosed. There's no inflammation.
Necrosis
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Grossly: Necrotic area appears well-defined, swollen, opaque, pale yellow or pale red. Surrounded by a red inflammatory zone.
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Microscopically:
- Cell membrane disappears. Cells become indistinct from each other.
- Cytoplasm swells and coagulates, appearing homogenous and deeply eosinophilic.
- Nucleus- characterized by pyknosis (shrunken and deeply basophilic), karyorrhexis (fragmented), and karyolysis (disappearance due to chromatin hydrolysis).
Types of Necrosis
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Coagulation Necrosis: Denaturation and coagulation of structural and enzymatic proteins. Cell outlines and tissue architecture are preserved. Examples: myocardial infarction due to coronary artery occlusion.
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Liquefactive Necrosis: Complete loss of cell and tissue structure due to liquefaction. Enzymes (autolysis or heterolysis) from cells or white blood cells break down the tissue. Examples: ischemic necrosis of brain (infarction), and pyogenic abscess (infection).
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Caseous Necrosis: Combination of coagulative and liquefactive necrosis. Tissue is firm grossly, but without cellular details microscopically. Example: Tuberculosis.
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Fat Necrosis: Necrosis of fat cells, caused by either trauma to fatty tissue or lipase enzyme action. Examples: Traumatic fat necrosis of the breast, Enzymatic fat necrosis of the pancreas and omentum in case of acute pancreatitis.
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Fibrinoid Necrosis: Death of cells in the inner layer of small blood vessels. It can lead to bleeding and internal damage throughout the body. Causes include malignant hypertension, autoimmune diseases (e.g., rheumatoid arthritis, lupus erythematosus), subacute bacterial endocarditis, and vasculitis (e.g., polyarteritis nodosa).
Apoptosis
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Morphologic Appearance:
- Cell shrinkage
- Deeply eosinophilic cytoplasm
- Pyknotic (shrunken), then fragmented nucleus
- Intact cell membrane (no rupture)
- Formation of cytoplasmic buds
- Each nuclear fragment goes with a cytoplasmic bud and breaks off to form apoptotic bodies.
- Phagocytosis of apoptotic bodies by adjacent cells or macrophages
- Absence of inflammatory response
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Physiological Examples:
- Embryogenesis (development of lumens in hollow organs)
- Hormone-dependent involution of tissues in adults (breast size changes after lactation, uterine involution after delivery).
- Removal of self-reacting T lymphocytes in the thymus.
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Pathological Examples:
- Councilman bodies in viral hepatitis (apoptotic hepatocytes)
- Tumor cell death
- Neuron loss in Alzheimer's disease
- HIV-positive T-lymphocytes die by apoptosis.
Apoptosis vs. Necrosis
| Feature | Necrosis | Apoptosis |
|---|---|---|
| Cell size | Enlarged (swelling) | Reduced (shrinkage) |
| Nucleus | Pyknosis, karyorrhexis, karyolysis | Fragmentation |
| Cellular contents | Enzymatic digestion; may leak out of cell | Intact; may be released in apoptotic bodies |
| Adjacent inflammation | Frequent | No |
| Physiologic/pathologic role | Always pathologic | Often physiologic; may be pathologic |
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Description
This quiz explores the different types of cell death, specifically necrosis and apoptosis. You will learn to recall the characteristics, examples, and morphological features associated with these processes. Compare and contrast necrotic cell types and apoptotic mechanisms for a deeper understanding of cellular responses to injury.
